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Recent Approvals
Patent Title: Fusion Bonding Process and Structure for Fabricating Silicon-on-Insulator (SOI)Semiconductor Devices
Patent No.: US 7,709,897
Date of Patent: May 4, 2010
Abstract:
A method of fabricating a semiconductor-on-insulator device including: providing a first semiconductor wafer having an about 200 angstrom thick oxide layer thereover; etching the first semiconductor wafer to raise a pattern therein; doping the raised pattern of the first semiconductor wafer through the about 200 angstrom thick oxide layer; providing a second semiconductor wafer having an oxide thereover; and, bonding the first semiconductor wafer oxide to the second semiconductor wafer oxide at an elevated temperature.
Patent Title: Signal Transmission System
Patent No.: US 7,685,880
Date of Patent: March 30, 2010
Abstract:
A single wire interface for a transducer transmits the transducer output as a frequency modulated signal over one single wire during one interval. During a second interval a reference signal is transmitted as a frequency modulated signal. Both the transducer output and the reference signal output are processed by the same circuitry during the respective intervals to provide both frequency modulated signals. The frequencies of the two signals are measured and then the ratio of the two periods which is the reciprocal of the two frequencies is calculated. This ratio is the direct measure of the output of the transducer and when provided eliminates sources of errors.
Patent Title: A Compact Absolute and Gage Pressure Transducer
Patent No.: US 7,673,518
Date of Patent: March 9, 2010
Abstract:
A compact absolute and gage pressure transducer consists of two sensors made from the same silicon wafer and adjacent each other on the wafer. The transducer contains a common header with a first and a second input port for receiving a first and a second pressure, respectively. The second port is directed through a reference tube into the hollow of a housing to apply pressure from the reference tube to the common sensor arrangement. The first port is directed from another surface of the housing to direct pressure to both sensor devices. One sensor operates as a gage sensor producing an output proportional to the difference between input pressures and the other sensor produces an absolute output. The sensor chip is associated with a sensor header which includes an alignment pin extending therefrom, and a guide plate with an aperture for accommodating an alignment pin.
Patent Title: A Combined Temperature and Pressure Transducer Incorporating Connector Keyway Alignment and an Alignment Method
Patent No.: US 7,669,479
Date of Patent: March 2, 2010
Abstract:
A transducer sensor is positioned within a hollow of the body of a housing. The housing has an extending alignment pin, which pin coacts with a corresponding slot or aperture in the wall of a vessel whose pressure or temperature is to be monitored. The transducer body is associated with a connector where the alignment pin is placed and extends from the housing in a fixed relation to the connector. A suitable aperture or slot in the wall of the vessel to be monitored accommodates the extending pin whereby when the transducer is placed in the vessel aperture the connector associated with the transducer is always located in proper position. Positioned on the housing is a sliding nut which can move in a direction parallel to the central axis of the housing and either to the right or left. This sliding nut is rotatably positioned in the housing and coacts with threads formed in the aperture in the wall of the vessel to enable tightening of the transducer housing when placed in the wall and when the alignment pin is positioned within the corresponding slot or aperture. This assures a proper alignment so that an external connector which is not moveable or rotatable can be immediately connected to the transducer connector without further experimentation or adjustment.
Patent Title: High Pressure Transducer Having an H Shaped Cross-Section
Patent No.: US 7,661,317
Date of Patent: February 16, 2010
Abstract:
A high pressure transducer has an H shaped cross-section with a center arm of the H having a top and bottom surface with the top surface of the H accommodating four strain gauges. Two strain gauges are located at the center of the top portion of the center arm of the H and are positive strain gauges, while two strain gauges are located near the periphery of the center arm of the gauge. The bottom surface of the center arm of the gauge has an active area of a smaller diameter than the circular diameter of the center arm portion of the transducer. The smaller active area is surrounded by a thicker stepped area which surrounds an active area on the pressure side of the H shaped member. The surrounding stepped area enables one to position the two negative strain gauges on the opposite surface of the center arm and near the periphery to thereby cause the negative gauges to respond to a negative stresses and therefore to enable one to provide a full Wheatstone bridge which includes the two positive strain gauges located at the center of the center arm of the H and the two negative peripheral gauges.
Patent Title: Personal Identification Apparatus Using Measured Tactile Pressure
Patent No.: US 7,642,894
Date of Patent: January 5, 2010
Abstract:
A personal identification system employs a matrix of pressure sensors mounted to a plate having a template of a human hand. When a person's hand is placed on the plate and overlying the template a pressure profile of the person's hand is provided. This profile is compared with a stored pressure profile of the same person's hand. If the pressure points or profiles correlate a positive identification of the person is made.
Patent Title: Beam Accelerometer With Limiting Apparatus
Patent No.: US 7,624,637
Date of Patent: December 1, 2009
Abstract:
An accelerometer includes a cantilever mass with a thin beam element between the mass and the fixed end of the accelerometer. The end of the mass is tapered. A limiting member has an aperture that is tapered corresponding to the taper at the end of the mass and positioned to surround the tapered end of the seismic mass. The beam accelerometer as well as the limiting member is placed in a cylindrical housing whereby the limiting member is moved along the taper of the seismic mass to adjust the spacing between the limiting member and the inner wall of the housing to thereby adjust the amount of movement of the seismic mass. In one embodiment the aperture of the tapered limited member also surrounds the seismic mass but the gap between the inner wall of the tapered limiting member and the outer wall of the seismic mass is adjusted to determine the amount of movement of the beam. In this manner, one can utilize a beam accelerometer arrangement of a cylindrical configuration within a housing and whereby the seismic mass has a taper and the taper coacts with a limiting member which has a corresponding taper to adjust the distance that the beam can move upon application of a force thereto.
Patent Title: High Accuracy, High Temperature, Redundant Media Protected Differential Transducers
Patent No.: US 7,610,812
Date of Patent: November 3, 2009
Abstract:
A semiconductor chip for use in fabricating pressure transducers, including: a semiconductor wafer having a top and a bottom surface, a layer of an insulating material formed on the top surface, the bottom surface having at least two recesses of substantially equal dimensions and spaced apart, the recesses providing first and second substantially equal thin active areas, which areas deflect upon application to a force applied to the top surface, a first plurality of piezoresistive devices arranged in a given pattern and positioned on the insulating material and located within the first area, a second equal plurality of piezoresistive devices arranged in the identical pattern and located on the insulating material within the second active area, first connecting means for connecting the first plurality of piezoresistive devices in a first array, second connecting means for connecting the second plurality of piezoresistive devices in a second array corresponding to the first array.
Patent Title: Apparatus and Method for Eliminating Varying Pressure Fluctuations in a Pressure Transducer
Patent No.: US 7,597,004
Date of Patent: October 6, 2009
Abstract:
A single pressure sensing capsule has a reference pressure ported to the rear side of a silicon sensing die. The front side of the silicon sensing die receives a main pressure at another port. The silicon sensing die contains a full Wheatstone bridge on one of the surfaces and within the active area designated as the diaphragm area. Thus, the difference of the main and reference pressure results in the sensor providing an output equivalent to the differential pressure, namely the main pressure minus the reference pressure which is the stress induced in a sensing diaphragm. In any event, the reference pressure or main pressure may be derived from a pump pressure which is being monitored. The pump pressure output is subjected to a pump ripple or a sinusoidally varying pressure. In order to compensate for pump ripple, one employs a coiled tube. The tube length is selected to suppress the pump ripple as applied to the sensor die. In this manner, the pump ripple cannot cause resonance which would result in pressure amplification and which pressure amplification would destroy the sensor.
Patent Title: Solid State Pressure Switch
Patent No.: US 7,595,570
Date of Patent: September 29, 2009
Abstract:
A personal identification system employs a matrix of pressure sensors mounted to a plate having a template of a human hand. When a person's hand is placed on the plate and overlying the template a pressure profile of the person's hand is provided. This profile is compared with a stored pressure profile of the same person's hand. If the pressure points or profiles correlate a positive identification of the person is made.
Patent Title: Combustion Transducer Apparatus Employing Pressure Restriction Means
Patent No.: US 7,584,665
Date of Patent: September 8, 2009
Abstract:
A pressure restrictor for use with a pressure sensing element comprising a cylindrical member of a given diameter and length having a plurality of apertures directed from a first end to a second end is disclosed. A pressure restrictor housing holds and positions the cylindrical member in close proximity to the pressure sensing element at the second end by clamping the pressure restrictor between the housing and element. The apertures provided in the pressure restrictor are the sole path for application of pressure to the sensing element. The sensing element is a double diaphragm silicon sensor where one diaphragm is exposed to pressure and the other diaphragm is not exposed to pressure. Each diaphragm has located thereon a half-bridge wherein both half bridges are connected to provide a full bridge. The full bridge provides an output strictly proportional to pressure.
Patent Title: High Pressure Transducer Having an H Shaped Cross-Section
Patent No.: US 7,559,248
Date of Patent: July 14, 2009
Abstract:
A high pressure transducer has an H shaped cross-section with a center arm of the H having a top and bottom surface with the top surface of the H accommodating four strain gauges. Two strain gauges are located at the center of the top portion of the center arm of the H and are positive strain gauges, while two strain gauges are located near the periphery of the center arm of the gauge. The bottom surface of the center arm of the gauge has an active area of a smaller diameter than the circular diameter of the center arm portion of the transducer. The smaller active area is surrounded by a thicker stepped area which surrounds an active area on the pressure side of the H shaped member. The surrounding stepped area enables one to position the two negative strain gauges on the opposite surface of the center arm and near the periphery to thereby cause the negative gauges to respond to a negative stresses and therefore to enable one to provide a full Wheatstone bridge which includes the two positive strain gauges located at the center of the center arm of the H and the two negative peripheral gauges.
Patent Title: Sensor For Measuring Low Dynamic Pressures in the Presence of High Static Pressures
Patent No.: US 7,559,246
Date of Patent: July 14, 2009
Abstract:
A sensor is described, which basically consists of a leadless high sensitivity differential transducer chip which responds to both static and dynamic pressure. Located on the transducer are two sensors. One sensor has a thicker diaphragm and responds to both static and dynamic pressure to produce an output indicative of essentially static pressure, the static pressure being of a much higher magnitude than dynamic pressure. The other sensor has a thinner diaphragm and has one side or surface responsive to both static and dynamic pressure. The other side of the differential sensor or transducer structure has a long serpentine reference tube coupled to the underneath of the diaphragm. The tube only allows static pressure to be applied on the underside of the diaphragm and because of the natural resonance frequency of the tube, the dynamic pressure is suppressed and does not, in any manner, interface with the sensor or transducer having a thinned diaphragm. Thus, the thinned diaphragm differential unit provides an output which is indicative of the dynamic pressure, as the static pressure applied to both the top and bottom surfaces of the transducer sensor is cancelled.
Patent Title: Method and System for Determining Gas Turbine Tip Clearance
Patent No.: US 7,540,704 B2
Date of Patent: June 2, 2009
Abstract:
A system for sensing at least one physical characteristic associated with an engine including a turbine having a plurality of blades turning inside a casing, the system including: a pressure sensor coupled substantially adjacent to the casing and including at least one output; a port in the turbine casing for communicating a pressure indicative of a clearance between the blades and casing to the pressure sensor; a cooling cavity substantially surrounding the pressure sensor; and, an inlet for receiving fluid from the engine and feeding the fluid to the cooling cavity to cool the pressure sensor; wherein, the pressure sensor output is indicative of the clearance between the blades and casing.
Patent Title: Pressure Transducer Adapted to Measure Engine Pressure Parameters
Patent No.: US 7,540,196 B2
Date of Patent: June 2, 2009
Abstract:
A pressure header assembly has a closed front and back surface. The back surface has an aperture for accommodating a separate dual die pressure header. The dual die pressure header has an absolute and differential pressure sensor positioned thereon. A differential pressure port is located on a side surface of the pressure header assembly and is directed to a bore in the pressure header assembly. The bore contains an elongated tube which is positioned in the pressure header assembly and locked in place by means of a crush nut and locking nut assembly. One end of the tube is coupled to the differential pressure port, while the other end of the tube accommodates a differential pressure tube which is bent in an arcuate position and directed to the underside of the sensor of the differential sensor assembly mounted in the dual die pressure header. Suitable leads from the dual die pressure header assembly are directed to a terminal board which is mounted within a pressure transducer housing shell, which terminal board coacts with an outboard contact cap assembly forming the transducer. The pressure header assembly portion also contains extending tabs which have apertures for external mounting.
Patent Title: Apparatus for Providing an Output Proportional to Pressure Divided by Temperature (P/T)
Patent No.: US 7,530,274 B2
Date of Patent: May 12, 2009
Abstract:
A circuit produces an output that is proportional to the molar density of gas in a chamber. The circuit employs an operational amplifier which measures the temperature using a RTD or other element that changes resistance with temperature. The RTD is placed such that it produces a decreasing current draw at the inverting input of the operational amplifier as the temperature increases. This decreasing current draw in turn produces a decreasing voltage at the output of the operational amplifier. By changing the ratio of resistors connected to the non-inverting terminal of the operational amplifier one changes the offset of the output voltage. By changing the feedback resistor connected from the output of the operational amplifier to the inverting terminal and connecting the output of the inverting terminal to a voltage divider including the RTD device, one can change the gain with temperature. Thus the output voltage of the operational amplifier is carefully controlled to be proportional to I/T for many different temperature scales and ranges. The output of the amplifier serves as the biasing voltage for a pressure transducer to provide a first output proportional to P/T. A second pressure transducer provides a second output proportional to P only.
Patent Title: High Pressure Delta P Sensor
Patent No.: US 7,526,962 B2
Date of Patent: May 5, 2009
Abstract:
A high pressure transducer has a metal housing with a main inlet high pressure port at one end and a reference pressure port at the other end. The ports communicate with a central hollow of the housing. Positioned in the hollow and communicating with the main inlet port is a first header welded to the housing and containing a first sensor device. Also positioned in the hollow and communicating with the reference pressure port is a second header also welded to the housing and having a second sensor device. There is another high pressure port on the housing and located between the inlet and reference ports to receive a main inlet high pressure as applied to said reference port. The applied pressures cause the first header weld to experience zero stress due to the application of the same main pressure to both the main inlet port and another pressure port. The second header weld experiences a weld pressure equal to the difference between the main high pressure and the reference pressure.
Patent Title: Joystick Sensor Apparatus
Patent No.: US 7,516,675 B2
Date of Patent: April 14, 2009
Abstract:
A joystick apparatus employs a hermetically sealed load cell having strain gauges placed on flexible beams formed on the load cell. All of the strain gauges are on the same surface of the load cell and therefore wiring is performed on a single side of the load cell. The strain gauges are enclosed in hermetically sealed cavity. The sensing diaphragm consists of a concentric thick inner and outer section joined by thinner diametrically opposed beam elements. The thin beam elements are compliant members which can deflect. Each beam includes strain gauges or sensor elements and the load cell is coupled to a joystick which when moved causes the beams to deflect to cause the sensor elements to produce an electrical output proportional to the force and direction of the joystick. The sensor can yield an output proportional to any angle over the 360° movement of the joystick to provide outputs proportional to the X and Y positions of said joystick. Thus, the joystick arrangement can resolve any angle or force into X and Y components for full directional control.
Patent Title: Silicon Carbide Piezoresistive Pressure Transducer and Method of Fabrication
Patent No.: US 7,516,668 B2
Date of Patent: April 14, 2009
Abstract:
A high temperature pressure transducer is fabricated from silicon carbide. A wafer of silicon carbide has reduced or active areas which act as deflecting diaphragms. Positioned on the reduced or active area is a silicon carbide sensor. The sensor is secured to the silicon carbide wafer by a glass bond. The pressure transducer is fabricated by first epitaxially growing a layer of highly N-doped 3C silicon carbide on a first silicon wafer or substrate. A second wafer of silicon carbide is selected to be a carrier wafer. The carrier wafer is etched preferentially to produce the deflecting members or reduced areas which serve as diaphragms. The 3C material on the silicon slice is patterned appropriately to provide a series of individual piezoresistors which then may be interconnected to form a Wheatstone bridge. The two wafers are joined together using a high temperature glass frit, such as a pyroceram, with the various resistor elements appropriately placed over the deflecting members of the silicon carbide wafer. The silicon on the silicon wafer is removed and various metallic contacts and interconnects are formed on the 3C silicon carbide resistor network.
Patent Title: Ultra Miniature Multi-Hole Probes Having High Frequency Response
Patent No.: US 7,484,418 B2
Date of Patent: February 3, 2009
Abstract:
A pressure probe includes a longitudinal tubular housing symmetrically disposed about a central axis and having an ultra miniature conical front end and an opened back end. A plurality of aperture ports having an opening are disposed about the front end. A plurality of ultra small leadless transducers has a central active deflecting area in a semiconductor substrate, and a layer of oxide on a bottom surface. At least one sensor network is disposed within the active area on the oxide layer. A glass contact wafer is bonded to the nondeflecting portion of sensing network and has a number of apertures surrounding the active area suitable for interconnection with the header. A header encloses each transducer and is of a shape and size to be positioned in an associated aperture port of the probe housing. At least one lead is coupled to a header pin extending from bottom of the aperture and directed through the bottom opening into the hollow of the probe housing.
Patent Title: Pressure Transducer Employing a Micro-Filter and Emulating an Infinite Tube Pressure Transducer
Patent No.: US 7,484,415 B2
Date of Patent: February 3, 2009
Abstract:
A pressure transducer for measuring pressures in high temperature environments employs a tube which is terminated at one end by an acoustic micro-filter. The acoustic filter or micro-filter has a plurality of apertures extending from one end to the other end, each aperture is of a small diameter as compared to the diameter of the transducer and the damper operates to absorb acoustic waves impinging on it with limited or no reflection. Mounted to the tube is a pressure transducer with a diaphragm flush with the inner wall of the tube. The tube is mounted in an aperture in a casing of a gas turbine operating at a high temperature. The hot gases propagate through the tube where the pressure of the gases are measured by the transducer coupled to the tube and where the acoustic filter operates to absorb acoustic waves impinging on it with little of no deflection, therefore enabling the pressure transducer to be mainly responsive to high frequency waves associated with the gas turbine operation.
Patent Title: High Temperature LC Pressure Transducer and Methods For Making the Same
Patent No.: US 7,478,562 B2
Date of Patent: January 20, 2009
Abstract:
A high temperature pressure capacitor is fabricated utilizing two high temperature substrate wafers. The substrates may be silicon carbide (SiC) or aluminum nitride (AIN). The first substrate has a metal conductive plate positioned on a top surface thereof. The top surface and plate are covered with a dielectric layer. The second substrate has a plate accommodating recess on the top surface thereof. Deposited in the recess is a second conductive plate. The first and second wafers are bonded together via the dielectric layer where the first and second plates face each other. Upon application of a force to the first wafer the diaphragm portion of the first wafer deflects causing the first plate to move and thereby varying capacitance. An inductor may be fabricated on a bottom surface of the second wafer to provide an LC circuit whose resonant frequency varies as a function of capacitance and therefore as a function of pressure.
Patent Title: Combined Temperature and Pressure Transducer Incorporating Connector Keyway Alignment and an Alignment Method
Patent No.: US 7,464,600 B2
Date of Patent: December 16, 2008
Abstract:
A transducer sensor is positioned with a hollow of the body of a housing. The housing has an extending alignment pin, which pin coacts with a corresponding slot or aperture in the wall of a vessel whose pressure or temperature is to be monitored. The transducer body is associated with a connector where the alignment pin is placed and extends from the housing in a fixed relation to the connector. A suitable aperture or slot in the wall of the vessel to be monitored accommodates the extending pin whereby when the transducer is placed in the vessel aperture the connector associated with the transducer is always located in proper position. Positioned on the housing is a sliding nut which can move in a direction parallel to the central axis of the housing and either to the right or left. This sliding nut is rotatably positioned in the housing and coacts with threads formed in the aperture in the wall of the vessel to enable tightening of the transducer housing when placed in the wall and when the alignment pin is positioned within the corresponding slot or aperture. This assures a proper alignment so that an external connector which is not moveable or rotatable can be immediately connected to the transducer connector without further experimentation or adjustment.
Patent Title: High Temperature Pressure Sensing System
Patent No.: US 7,451,655 B2
Date of Patent: November 18, 2008
Abstract:
A high temperature pressure sensing system (transducer) including: a piezoresistive sensor formed by a silicon-on-insulator (SOI) process; a SOI amplifier circuit operatively coupled to the piezoresistive sensor; a SOI gain controller circuit including a plurality of resistances that when selectively coupled to the amplifier adjust a gain of the amplifier; a plurality of off-chip contacts corresponding to the resistances, respectively, for electrically activating the corresponding resistances and using a metallization layer for the SOI sensor and SOI ASIC suitable for high temperature interconnections (bonding); wherein the piezoresistive sensor, amplifier circuit and gain control circuit are suitable for use in environments having a temperature greater than 175 degrees C. and reaching between 250°C. and 300°C., and wherein the entire transducer has a high immunity to nuclear radiation.
Patent Title: Method and Apparatus for Measuring Knocking in Internal Combustion Engines
Patent No.: US 7,448,254 B2
Date of Patent: November 11, 2008
Abstract:
A method and apparatus for measuring knocking in internal combustion engines employs a high temperature transducer, which transducer is mounted within a cylinder. The output of the transducer is solely related to pressure. The output signal from the transducer is directed to the input of a high frequency amplifier associated with a band pass filter. In this manner the combustion signal can be filtered out and one provides a signal which is only indicative of the knocking signal and of the knocking frequencies. This signal can be analyzed simply and effectively by the use of a processor such as a multimeter or a microprocessor. In a similar manner the processor can compare the combustion and knocking signal without the band pass filtering with the knocking signal with the combustion signal filtered out.
Patent Title: Displacement Transducer
Patent No.: US 7,444,879 B2
Date of Patent: November 4, 2008
Abstract:
A displacement transducer includes a load cell structure having a thick outer peripheral area, a thick inner central area and two symmetrical thin beams. The two beams are disposed along a common diameter of the structure and joins the outer peripheral area and the inner central area. At least one strain gauge is placed on a surface of the second beam. A top diaphragm cover member is secured to a top surface of the outer peripheral area and covers the two beams.
Patent Title: Micromachined Optical Pressure Sensor
Patent No.: US 7,440,645 B2
Date of Patent: October 21, 2008
Abstract:
A pressure sensor including: a deflectable diaphragm including a substantially central boss and channel; and, an optical waveguide having first and second arms, wherein the first arm is substantially aligned with an edge of the boss and the second arm is substantially aligned with an edge of the channel.
Patent Title: Fusion Bonding Process and Structure for Fabricating Silicon-On-Insulator (SOI) Semiconductor Devices
Patent No.: US 7,439,159 B2
Date of Patent: October 21, 2008
Abstract:
A method of fabricating a semiconductor-on-insulator device including; providing a first semiconductor wafer having an about 200 angstrom thick oxide layer thereover; etching the first semiconductor wafer to raise a pattern therein; doping the raised pattern of the first semiconductor wafer through the about 200 angstrom thick oxide layer; providing a second semiconductor wafer having an oxide thereover; and, bonding the first semiconductor wafer oxide to the second semiconductor wafer oxide at an elevated temperature.
Patent Title: Moisture Resistant Pressure Sensors
Patent No.: US 7,436,037 B2
Date of Patent: October 14, 2008
Abstract:
A differential pressure sensor has a semiconductor wafer having a top and bottom surface. The top surface of the wafer has a central active area containing piezoresistive elements. These elements are passivated and covered with a layer of silicon dioxide. Each element has a contact terminal associated therewith. The semiconductor wafer has an outer peripheral silicon frame surrounding the active area. The semiconductor wafer is bonded to a glass cover member via an anodic or electrostatic bond by bonding the outer peripheral frame to the periphery of the glass wafer. An inner silicon dioxide frame forms a compression bond with the glass wafer when the glass wafer is bonded to the silicon frame. This compression bond prevents deleterious fluids from entering the active area or destroying the silicon. The above described apparatus is mounted on a header such that through holes in the glass wafer are aligned with the header terminals. The header has pins which are directed from the header terminals to enable contact to be made to the unit. Both the top and bottom surfaces of the semiconductor wafer are coated with silicon dioxide which acts to protect al the elements from deleterious substances. Thus a first pressure is applied to one surface and a second pressure is applied to the other surface to enable differential operations.
Patent Title: Pressure Sensor Heading Having an Integrated Isolation Diaphragm
Patent No.: US 7,432,795 B2
Date of Patent: October 7, 2008
Abstract:
A pressure sensor header for a pressure transducer includes a header shell having a sensor cavity formed therein, a sensor element disposed in the sensor cavity, a fluid medium disposed in the sensor cavity, an isolation diaphragm closing the sensor cavity, and a joining arrangement disposed at an interface of the isolation diaphragm and the header shell, the joining arrangement joining the isolation diaphragm with the header shell. The isolation diaphragm is an integral, unit comprising a thin membrane surrounded by a thicker outer ring. The joining arrangement has a recessed female joining element formed in one of the outer ring of the isolation diaphragm and the header shell, and a protruding male joining element formed on the other one of the outer ring of the isolation diaphragm and the header shell, the male joining element received in the female joining element.
Patent Title: Signal Transmission System
Patent No.: US 7,409,866 B2
Date of Patent: August 12, 2008
Abstract:
A single wire interface for a transducer transmits the transducer output as a frequency modulated signal over one single wire during one interval. During a second interval a reference signal is transmitted as a frequency modulated signal. Both the transducer output and the reference signal output are processed by the same circuitry during the respective intervals to provide both frequency modulated signals. The frequencies of the two signals are measured and then the ration of the two periods which is the reciprocal of the two frequencies is calculated. This ration if the direct measure of the output of the transducer and when provided eliminates sources of errors.
Patent Title: Method of Joining a Pressure Sensor Header With an Associated Transducer Element
Patent No.: US 7,369,032 B2
Date of Patent: May 6, 2008
Abstract:
A pressure transducer assembly including: a pressure sensor header; a transducer assembly member; and a joining arrangement disposed at an interface of the header and the transducer assembly member, for joining the header with the transducer assembly member, the joining arrangement including: a recessed female joining element formed in one of the header and the transducer assembly member; and a protruding male joining element formed on the other of the header and the transducer assembly member, the male joining element received in the female joining element.
Patent Title: Ultra High Temperature Hermetically Protected Wirebonded Piezoresistive Transducer
Patent No.: US 7,363,820 B2
Date of Patent: April 29, 2008
Abstract:
An ultra high temperature hermetically protected transducer includes a sensor chip having an active area upon which is deposited piezoresistive sensing elements. The elements are located on the top surface of the silicon wafer chip and have leads and terminals extending from the active area of the chip. The active area is surrounded with an extending rim or frame. The active area is coated with an oxide layer which passivates the piezoresistive sensing network. The chip is then attached to a glass pedestal, which is larger in size than the sensor chip. The glass pedestal has a through hole or aperture at each corner. The entire composite structure is then mounted onto a high temperature header with the metallized regions of the header being exposed to the holes in the glass pedestal; a high temperature lead is then bonded directly to the metallized contact area of the sensor chip at one end. The leads are of sufficient length to extend into the through holes in the glass pedestal. A sealing cover is then attached to the entire composite sensor to hermetically seal all of the interconnections. The sealing cover is a glass structure, has a central aperture which corresponds to the aperture formed by the frame, allowing the active area of the sensor to be exposed to the pressure medium. The sealing cover is bonded to the periphery of the rim and to the glass supporting pedestal.
Patent Title: Quantum Dot Based Pressure Switch
Patent No.: US 7,358,581 B2
Date of Patent: April 15, 2008
Abstract:
A semiconductor heterostructure based pressure switch comprising: first and second small bandgap material regions separated by a larger bandgap material region; a third small bandgap material region within the region of larger bandgap material, the third material region and larger bandgap material region defining at least one quantum dot; and, first and second electrodes electrically coupled to the first and second small bandgap material regions, respectively, wherein the electrodes are sufficiently proximate to said quantum dot to facilitate electron tunneling there between when a pressure is appllied to the bandgap material defining the quantum dot.
Patent Title: Apparatus For Providing an Output Proportional to Pressure Divided By Temperature (P/T)
Patent No.: US 7,347,098 B2
Date of Patent: March 25, 2008
Abstract:
A circuit produces an output that is proportional to the molar density of gas in a chamber. The circuit employs an operational amplifier which measures the temperature using RTD or other element that changes resistance with temperature. The RTD is placed such that it produces a decreasing current draw at the inverting input of the operational amplifier as the temperature increases. This decreasing current draw in turn produces a decreasing voltage at the output of the operational amplifier. By changing the ratio of resistors connected to the non-inverting terminal of the operational amplifier one changes the offset of the output voltage. By changing the feedback resistor connected from the output of the operational amplifier to the inverting terminal and connecting the output of the inverting terminal to a voltage divider including the RTD device,, one can change the gain with temperature. Thus the output voltage of the operational amplifier is carefully controlled to be proportional to P/T for many different temperature scales and ranges. The output of the amplifier serves as the biasing voltage for a pressure transducer.
Patent Title: Line Pressure Compensated Differential Pressure Transducer Assembly
Patent No.: US 7,343,808 B2
Date of Patent: March 18, 2008
Abstract:
A pressure transducer apparatus including: first and second pluralities of piezoresistors each coupled in Wheatstone bridge configurations, wherein the bridges are coupled together to provide a first output being indicative of a differential pressure; and, a third plurality of piezoresistors coupled in a Wheatstone bridge configuration and being suitable for providing a second output being indicative of an absolute line pressure. A compensator may be employed for adjusting the first output for line pressure variation responsively to the second output.
Patent Title: Low Cost Pressure Sensor For Measuring Oxygen Pressure
Patent No.: US 7,331,241 B2
Date of Patent: February 19, 2008
Abstract:
A low cost sensor assembly for measuring oxygen pressures contains a transistor header. The transistor header has terminal pins extending there from. The transistor header co-acts with a first circuit insulator board. The first circuit board has deposited thereon four hand mirror shaped contact areas each one associated with one of the terminal pins of the transistor header. The top portion of each contact area has an aperture with the extending arm of the area directed towards the center of the board. The board is epoxied to the transistor header with the terminal pins of the header extending into the apertures of the contact board. A second contact board is then epoxied to the first contact board. The second contact board has a series of four apertures located at the center. Each of the apertures of the second board contacts the handle portion of the mirror patterns of the first board. A leadless piezoresistive sensor assembly is then positioned and secured to the second board whereby the terminals from the sensor assembly align with each of the apertures in the second board. The terminals of the sensor assembly are apertures filled with a conductive glass metal frit and each filled aperture makes contact with a terminal of the sensor. The configuration has all conductive terminals of the entire device completely isolated and insulated from the oxygen environment, thus preventing ignition of the oxygen.
Patent Title: Hermetically Sealed Displacement Sensor Apparatus
Patent No.: US 7,284,444 B2
Date of Patent: October 23, 2007
Abstract:
A hermetically sealed displacement sensor has strain gauges placed on thin flexible triangular shaped beams of a load beam cell. The strain gauges are enclosed in a hermetically sealed cavity which cavity is sealed by means of a cover plate placed over the load beam cell. The thin beams are connected together by a center hub and basically form two constant moment beams. There is a top isolation diaphragm member which is convoluted and to which a force is applied which applied force is transmitted to the thin flexible beams. The beams deflect and the sensors produce an output proportional to strain. The sensors on each beam are two in number wherein one sensor is placed in a longitudinal direction with respect to the beam while the other sensor is in a transverse position. The sensors may be wired to form a full Wheatstone bridge or half bridges may be employed. The electrical output from the strain gauge bridge is proportional to the deflection of the center of the sensor.
Patent Title: Line Pressure Compensated Differential Pressure Transducer Assembly
Patent No.: US 7,284,440 B2
Date of Patent: October 23, 2007
Abstract:
A pressure transducer apparatus including: first and second pluralities of piezoresistors each coupled in Wheatstone bridge configurations, wherein the bridges are coupled together to provide a first output being indicative of a differential pressure; and, a third plurality of piezoresistors coupled in a Wheatstone bridge configuration and being suitable for providing a second output being indicative of an absolute line pressure. A compensator may be employed for adjusting the first output for line pressure variation responsively to the second output.
Patent Title: Transducer Employing Wireless Transmissions For Sending And Receiving Signals
Patent No.: US 7,283,922 B2
Date of Patent: October 16, 2007
Abstract:
A transducer is implemented to operate with transmitted frequency signals. These transmitted signals provide a bias potential to the transducer and enable the transducer to transmit a transducer output signal to a remote location. The transducer has an antenna for receiving transmitted signals. The antenna is coupled to a rectifier circuit; the rectifier circuit is operative to provide a DC voltage in response to said transmitted signals. This DC voltage is applied to the piezoresistive array via a switching arrangement coupled between the array and the rectifier circuit. An interface circuit controls the switching arrangement to enable DC bias to be applied to the array in a first mode and to remove the bias in a second mode.
Patent Title: Stop Assembly For A Beam Type Load Cell
Patent No.: US 7,275,452 B2
Date of Patent: October 2, 2007
Abstract:
A beam load cell transducer is positioned between a stationary member and a moveable member. The stationary member, as well as the moveable member are surrounded by a collar, which collar has an inner surface means to limit the movement of the moveable member of the transducer. By limiting the movement and restraining further movement after a predetermined excessive force is applied, one stops the beam and therefore prevents the beam from fracturing or rupturing. In the unlikely event that the beam does fracture or rupture, then the sleeve acts to hold the entire unit together, thereby maintaining integrity to the transducer.
Patent Title: Pressure Transducer Apparatus Adapted To Measure Engine Pressure Parameters
Patent No.: US 7,275,444 B1
Date of Patent: October 2, 2007
Abstract:
A pressure header assembly has a closed front and back surface. The back surface has an aperture for accommodating a separate dual die pressure header. The dual die pressure header has an absolute and differential pressure sensor positioned thereon. A differential pressure port is located on a side surface of the pressure header assembly and is directed to a bore in the pressure header assembly. The bore contains an elongated tube which is positioned in the pressure header assembly and locked in place by means of a crush nut and locking nut assembly. One end of the tube is coupled to the differential pressure port, while the other end of the tube accommodates a differential pressure tube which is bent in an arcuate position and directed to the underside of the sensor of the differential sensor assembly mounted in the dual die pressure header. Suitable leads from the dual die pressure header assembly are directed to a terminal board which is mounted within a pressure transducer housing a shell, which terminal board coacts with an outboard contact cap assembly forming the transducer. The pressure header assembly portion also contains extending tabs which have apertures for external mounting.
Patent Title: Dual Layer Color-Center Patterned Light Source
Patent No.: US 7,260,127 B2
Date of Patent: August 21, 2007
Abstract:
A thin layer of ionic crystal is grown on a substrate. The crystal could be any type of ionic crystal, such as sodium chloride or potassium chloride. The crystal is a pure form of the chosen compound and may contain contaminants, which would shift the wavelength of created color centers. On top of the first crystal layer, a second thin layer of a different type of crystal is deposited, such as lithium fluoride or sodium fluoride. When these two layers are radiated with gamma rays, they will each form color centers at the spots radiated. Because of the difference in crystalline properties of the two different ionic crystals centers, their color centers would be a t different wavelengths. Each of the two separate ionic crystals will emit light at different characteristic wavelengths when illuminated at their unique absorption frequencies. Each layer can be made to lase separately. The top layer has an absorption energy greater than that of the bottom layer, so that the layer energy of the bottom layer absorption peak will pass through the top layer and be absorbed only by the bottom layer. There are many ways of forming F-centers in the two superimposed layers, such as by the use of selective gamma radiation by heating of an anion layer of the particular compound and then depositing the second ionic crystal on the first ionic crystal and then depositing an anion layer on the second crystal and then heating to produce a structure which will lase it to the different frequencies.
Patent Title: High Accuracy, High Temperature, Redundant Media Protected Differential Transducers
Patent No.: US 7,258,018 B2
Date of Patent: August 21, 2007
Abstract:
A semiconductor chip for use in fabricating pressure transducers, including: a semiconductor wafer having a top and a bottom surface, a layer of an insulating material formed on the top surface, the bottom surface having at least two recesses of substantially equal dimensions and spaced apart, the recesses providing first and second substantially equal thin active areas, which areas deflect upon application to a force applied to the top surface, a first plurality of piezoresistive devices arranged in a given pattern and positioned on the insulating material and located within the first area, a second equal plurality of piezoresistive devices arranged in the identical pattern and located on the insulating material within the second active area, first connecting means for connecting the first plurality of piezoresistive devices in a first array, second connecting means for connecting the second plurality of piezoresistive devices in a second array corresponding to the first array.
Patent Title: Pressure Sensor Header Having An Integrated Isolation Diaphragm
Patent No.: US 7,212,096 B2
Date of Patent: May 1, 2007
Abstract:
A pressure sensor header for a pressure transducer includes a header shell having a sensor cavity formed therein, a sensor element disposed in the sensor cavity, a fluid medium disposed in the sensor cavity, an isolation diaphragm closing the sensor cavity, and a joining arrangement disposed at an interface of the isolation diaphragm and the header shell, the joining arrangement joining the isolation diaphragm with the header shell. The isolation diaphragm is an integral unit comprising a thin membrane surrounded by a thicker outer ring. The joining element formed in one of the outer ring of the isolation diaphragm and the header shell, and a protruding male joining element formed on the other one of the outer ring of the isolation diaphragm and the header shell, the male joining element received in the female joining element.
Patent Title: System And Method For Determining Flow Characteristics
Patent No.: US 7,201,067 B2
Date of Patent: April 10, 2007
Abstract:
A fluid flow probe including: first, second and third pressure sensors; a first port for communicating a first pressure to the first pressure sensor; a second port for communicating a second pressure to the second pressure sensor, the second port being substantially oppositely disposed with respect to the first port, a third pressure port suitable for communicating a static pressure to the third pressure sensor; first and second outputs electrically coupled to the first and second pressure sensors, respectively, one of the first and second outputs indicative of a total pressure and the other of the outputs indicative of a base pressure; and, a third output electrically coupled to the third pressure sensor and indicative of the static pressure.
Patent Title: Miniature Reaction Chamber Template Structure For Fabrication Of Nanoscale Molecular Systems And Devices
Patent No.: US 7,189,378 B2
Date of Patent: March 13, 2007
Abstract:
A unique, micro-miniature reaction chamber template structure is disclosed for the fabrication of nanoscale molecular systems and devices. The structure is composed of multiple layers of silicon (either doped or intrinsic), Pyrex and various metals. The silicon may or may not be totally or partially covered with silicon dioxide. The Pyrex is chosen to be suitable for field-assisted bonding to silicon and the various metal layers are selected for their adherence to silicon or Pyrex, as well as their conductivity and their chemical reactivity. The basis structure may contain a number of tubes or fluidic pipes of varying cross sections. The structure consists of a layer of silicon bonded to a layer of Pyrex, which is in turn bonded to another layer of silicon and therefore, there is a composite structure which consists of a laminate of silicon glass and silicon. The glass is extremely thin and is Pyrex having sodium ions, which will be transported upon the application of a voltage to the structure to cause the sodium ions to be transported, leaving the dangling oxygen bonds in the glass or the silicon layers.
Patent Title: Low Pass Filter Semiconductor Structures For Use In Transducers For Measuring Low Dynamic Pressures In The Presence Of High Static Pressures
Patent No.: US 7,188,528 B2
Date of Patent: March 13, 2007
Abstract:
A semiconductor filter is provided to operate in conjunction with a differential pressure transducer. The filter receives a high and very low frequency static pressure attendant with a high frequency low dynamic pressure at one end, the filter operates to filter said high frequency dynamic pressure to provide only the static pressure at the other filter end. A differential transducer receives both dynamic and static pressure at one input port and receives said filtered static pressure at the other port where said transducer provides an output solely indicative of dynamic pressure. The filter in one embodiment has a series of etched channels directed from an input end to an output end. The channels are etched pores of extremely small diameter and operate to attenuate or filter the dynamic pressure. In another embodiment, a spiral tubular groove is found between a silicon wafer and a glass cove wafer, an input port of the groove receives both the static and dynamic pressure with an input port of the groove providing only static pressure. The groove filters attenuate dynamic pressure to enable the differential transducer to provide an output only indicative of dynamic pressure by cancellation of the static pressure.
Patent Title: Vibration Isolated Transducer Connector
Patent No.: US 7,186,131 B2
Date of Patent: March 6, 2007
Abstract:
A transducer including a transducer body, a sensor associated with the transducer body, an electrical connector assembly fastened to an end of the transducer body, and a vibration damper system disposed between the end of the transducer body and the electrical connector assembly. The vibration damper system being operative for attenuating vibrational acceleration and amplification forces experienced by the electrical connector assembly when the transducer is exposed to vibration.
Patent Title: Moisture Resistant Differential Pressure Sensors
Patent No.: US 7,183,620 B2
Date of Patent: February 27, 2007
Abstract:
A differential pressure sensor has a semiconductor wafer having a top and bottom surface. The top surface of the wafer has a central active area containing piezoresistive elements. These elements are passivated and covered with a layer of silicon dioxide. Each element has a contact terminal associated therewith. The semiconductor wafer has an outer peripheral silicon fame surrounding the active area. The semiconductor wafer is bonded to a glass cover member via an anodic or electrostatic bond by bonding the outer peripheral frame to the periphery of the glass wafer. An inner silicon dioxide frame forms a compression bond with the glass wafer when the glass wafer is bonded to the silicon frame. This compressipon bond prevents deleterious fluids from entering the active area or destroying the silicon. The above-described apparatus is mounted on a header such that through holes in the glass wafer are aligned with the header terminals. The header has pins, which are directed from the header terminals to enable contact to be made to the unit. Both the top and bottom surfaces of the semiconductor wafer are coated with silicon dioxide, which acts to protect all the elements from deleterious substances. Thus a first pressure is applied to one surface and a second pressure is applied to the other surface to enable differential operation.
Patent Title: Personal Identification Apparatus Using Measured Tactile Pressure
Patent No.: US 7,180,401 B2
Date of Patent: February 20, 2007
Abstract:
A personal identification system employs a matrix of pressure sensors mounted to a plate having a template of a human hand. When a person’s hand is placed on the plate and overlaying the template a pressure profile of the person’s hand is provided. This profile is compared with a stored pressure profile of the same person’s hand. If the pressure points or profiles correlate a positive identification of the person is made.
Patent Title: Transducer Responsive To Pressure, Vibration/Acceleration And Temperature And Methods Of Fabricating The Same
Patent No.: US 7,178,403 B2
Date of Patent: February 20, 2007
Abstract:
A pressure sensing device produces an output proportional to applied pressure irrespective of vibration/acceleration of the device, which device also provides an output proportional only to vibration/acceleration of the device irrespective of the pressure.
Patent Title: Resonating Transducer
Patent No.: US 7,155,980 B2
Date of Patent: January 2, 2007
Abstract:
A resonating pressure transducer operable to measure an applied pressure by measuring changes in a resonant frequency is disclosed. The pressure transducer comprises a plurality of diaphragms formed in a wafer of semi-conducting material between two layers, wherein each of the diaphragms is divided into a plurality of electrically isolated sections; a cavity in one of the covering layers opposite a corresponding one of the diaphragms, a first via formed through a selected one of the layers enables application of a potential to selected ones of the diaphragm sections; and a second via formed through a selected one of the layers enables transmission of a measure from selected ones of the diaphragm sections.
Patent Title: Vibration Isolated Transducer Connector
Patent No.: US 7,186,131 B2
Date of Patent: September 19, 2006
Abstract:
A sensor is described, which basically consists of a leadless high sensitivity differential transducer chip which responds to both static and dynamic pressure. Located on the transducer are two sensors. One sensor has a thicker diaphragm and responds to both static and dynamic pressure to produce an output indicative of essentially static pressure, the static pressure being of a much higher magnitude than dynamic pressure. The other sensor has a thinner diaphragm and has one side or surface responsive to both static and dynamic pressure. The other side of the differential sensor or transducer structure has a long serpentine reference tube coupled to the underneath of the diaphragm. The tube only allows static pressure to be applied on the underside of the diaphragm and because of the natural resonance frequency of the tube, the dynamic pressure is suppressed and does not, in any manner, interface with the sensor or transducer having a thinned diaphragm. Thus, the thinned diaphragm differential unit provides an output which is indicative of the dynamic pressure, as the static pressure applied to both the top and bottom surfaces of the transducer sensor is canceled.
Patent Title: Multi-Load Beam Apparatus To Prevent Improper Operation Due To Off-Axis Loads
Patent No.: US 7,086,299 B2
Date of Patent: August 8, 2006
Abstract:
A multi-load beam transducer includes a fixed member, a movable member, and a plurality of load beams positioned between the members, each beam separated by a given distance normal from each other and positioned about a longitudinal axis between the members. The plurality of load beams are responsive to forces exerted on the members. The transducer further includes a plurality of resistors positioned on selected ones of the plurality of load beams. The resistors have a resistance value which varies with an applied force with the plurality of resistors electrically connected and operable to determine the value of the applied force.
Patent Title: Shunt Calibration For Electronic Pressure Switches
Patent No.: US 7,073,389 B2
Date of Patent: July 11, 2006
Abstract:
An electronic switch of the type uses a piezoresistive Wheatstone bridge configuration to sense pressure. The output of the Wheatstone bridge is applied to an electronic control circuit which contains a comparator. The comparator monitors the output of the bridge and if the output voltage of the bridge exceeds a predetermined value, as indicated by the comparator, a switch is closed to illuminate a lamp indicating to the operator that the pressure has been exceeded. One terminal of the resistor is coupled to a switch which when operated, causes the resistor to be connected in parallel with one of the arms of the bridge, thereby producing an imbalance of the bridge. This imbalance, due to the shunting of the arm of the bridge by the resistor, causes the electronic control circuit to recognize an excessive pressure, whereby the electronics control circuit generates an output signal which cause the electronic switch to close, thereby illuminating the lamp.
Patent Title: Combined Absolute Differential Transducer
Patent No.: US 7,057,247 B2
Date of Patent: June 6, 2006
Abstract:
There is disclosed a combined absolute differential pressure transducer which consists of two sensors made from the same wafer silicon and selected to be adjacent to each other on the wafer. Since the same pressure is applied to the boss side of both sensors and a second pressure is applied to the opposite side of the differential sensor, deflection and the stress of the second sensor is determined by the pressure difference across the deflecting portion of the senor. To obtain the same stresses in the tin section of each sensor, the overall active area of each sensor is different. For the same thickness read, the absolute value of P2–P1 where P2 is the pressure applied to the front side of the two sensors and P1 is the pressure applied to the differential sensor through the metal tube is less than P2 to obtain the same stress in each sensor a great active area in the differential sensor is required. Conversely, if the absolute value of P2–P1 is greater than P2, then a smaller active area in the differential sensor is required. By choosing adjacent sensors with the same web thickness, but different size active areas the thermal co-efficient and the thermal sensitivity are controlled by the impurity concentrations of the P regions and by how well they match each other. Thus, the thermal properties of the two individual sensors are closely controlled and matched to each other resulting in an improved overall combined absolute differential transducer.
Patent Title: Solid State Electronic Pressure Switch
Patent No.: US 7,034,700 B2
Date of Patent: April 25, 2006
Abstract:
An electronic single pole double throw switch has two states. In each state, one of the lamps is on and the other lamp is off. In the electronic switch, the voltage, which is at the output terminal of the lamp that is off is utilized to drive a low voltage regulator which operates electronic circuitry associated with the electronic switch.
Patent Title: Load Beam Apparatus Operative To Prevent Improper Operation Due To Off Axis Load
Patent No.: US 7,000,484 B2
Date of Patent: February 21, 2006
Abstract:
A beam transducer employs a linear bearing which surrounds the active element of the transducer which is the beam. One end of the bearing is welded to the inactive end of the load beam. The other end of the bearing is not welded, allowing the active end of the beam to move freely. The linear bearing eliminates friction and jamming which will cause inaccurate load measurement, but the ability to allow the active element to move freely with one end free enables the load beam sensitivity to be maximized. The free end is sealed environmentally by employing a flexible metal membrane or diaphragm, which is welded between the bearing end and the load beam. This configuration provides a hermetic seal to protect the load beam and the sensitive gages which are placed on the load beam.
Patent Title: Transducer With Integral Switch For Wireless Electronics
Patent No.: US 6,941,816 B2
Date of Patent: September 13, 2005
Abstract:
There is disclosed a transducer with an integral switch for wireless electronics. Essentially, the transducer contains a housing which includes a sensor device. The sensor device may be a piezoresistive Wheatstone bridge arranged in a conventional manner. The output of the bridge is coupled to a typical amplifying circuit or an analog-to-digital converter whose signal is coupled to a suitable transmitting means. The signal provided by the Wheatstone bridge is transmitted through RF, infrared or some other wireless transmission scheme to a remote location. Such transmissions schemes are well known. Associated with the sensor and secured to the sensing housing, is a push button switch which is wired in series with a battery. The battery operates to energize the sensor, including all the electronics when the sensor is placed in a pressure sensing position. When the pressure is placed in a pressure sensing position, the push button switch, is actuated to apply operating bias to the transducer device.
Patent Title: Pressure Transducer Capable Of Detecting Internal Leakage Of External Media
Patent No.: US 6,935,184 B2
Date of Patent: August 30, 2005
Abstract:
A pressure transducer capable of detecting leakage of media into the pressure transducer. The pressure transducer comprises a spacer having first and second ends. A first header assembly containing a first pressure sensor for measuring a pressure of the media, is sealingly disposed at the first end of the spacer. A second header assembly containing a second pressure sensor, is sealingly disposed at the second end of the spacer. The spacer, first header assembly, and second header assembly form a hermetically sealed leak detection cavity for capturing the media that leaks past the first header assembly. In operation, the media captured in the leak detection cavity generates a pressure which is sensed by the second pressure sensor.
Patent Title: High Temperature Sensors Utilizing Doping Controlled, Dielectrically Isolated Beta Silicon Carbide (SiC) Sensing Elements On A Specifically Selected High Temperature Force Collecting Membrane
Patent No.: US 6,900,108 B2
Date of Patent: May 31, 2005
Abstract:
Semiconductor devices useful in high temperature sensing applications include a silicon carbide substrate, a silicon dioxide layer, and an outer layer of crystalline doped silicon carbide. The device is a 3CÐSiC/SiO2/SiC structure. This structure can be employed to fabricate high temperature devices such as piezoresistive sensors, minority carrier devices and so on. The crystalline doped silicon carbide is dielectrically isolated from the substrate. The devices are formed by processes that include bonding a pattern wafer to a substrate wafer, selective oxidation and removal of undoped silicon, and conversion of doped silicon to crystalline silicon carbide. The level of doping and the crystalline structure of the silicon carbide can be selected according to desired properties for particular applications.
Patent Title: Apparatus And Method For Interconnecting Leads In A High Temperature Pressure Transducer
Patent No.: US 6,895,822 B2
Date of Patent: May 24, 2005
Abstract:
A novel method for interconnecting leads in a high pressure transducer without the use of solder employs a ceramic disc containing a number of through holes. Each hole has a tube inserted therein, which tubes are connected to the disc by brazing or a high temperature attachment. Each tube protrudes from both sides of the ceramic. The ceramic is coated in appropriate areas with molymanganese film, which is over plated with gold. This overcoat forms a brazed compound surface attached to the tubes of the ceramic. A semiconductor pressure transducer has output leads which are inserted through the ceramic into each tube. The other side end of the tube receives high temperature wires from a suitable connecting device. Each tube is then crimped and spot-welded to hold both the lead from the transducer and the high temperature leads to produce a strong bond without the use of solder. The header itself is typically welded to a pressure point.
Patent Title: Ultra-Miniature, High Temperature, Capacitive Inductive Pressure Transducer
Patent No.: US 6,891,711 B2
Date of Patent: May 10, 2005
Abstract:
An ultra miniature high temperature capacitive inductive pressure transducer is fabricated by MEMS techniques. The transducer consists of two separated pieces of silicon which form the plates of the capacitor, one of which plate is micromachined in such a way to allow a controlled deflection with pressure. The gap between the two capacitive plates is determined by an extending rim on one of the two plates. The two pieces of silicon are subsequently fusion bonded, leading a very small gap between the two plates. An inductor is formed on the top surface of one of the pieces of silicon by sputtering metal in a spiral like fashion on the back side of the micro-machined plate.
Patent Title: Doubly Compensated Pressure Transducer
Patent No.: US 6,877,379 B2
Date of Patent: April 12, 2005
Abstract:
The present invention relates to a compensated pressure transducer having a pressure transducer connected to a coarse temperature adjustment compensator and to a fine temperature adjustment compensator. The coarse temperature adjustment compensator includes an analog circuit and the fine temperature adjustment compensator includes a digital circuit. A pre-amplifier is connected between the pressure transducer and the fine temperature adjustment compensator.
Patent Title: System For Detecting and Compensating For Aerodynamic Instabilities in Turbo-Jet Engines
Patent No.: US 6,871,487 B2
Date of Patent: March 29, 2005
Abstract:
The present invention relates to a system for detecting aerodynamic instabilities in a jet turbine engine having a pressure transducer mounted in the engine. The pressure transducer, welded to a circuit in signal communication with a controller, is adapted to send measured pressure readings from air in a combustion chamber to the controller. The controller, located in spaced apart relation from the engine, is adapted by software to detect pressure patterns from the pressure signals generated by the transducer that are indicative of a stall or surge. A series of fuel and air valves located with compression and combustion chambers of the engine are in signal communication with the controller. The controller in response to detecting pressure signals indicating a stall or surge is operative to signals in the valves to change the air flow, air angle, fuel flow or speed to reduce the possibility of a stall or surge.
Patent Title: Method For Fabricating A Single Chip Multiple Range Pressure Transducer Device
Patent No.: US 6,861,276 B2
Date of Patent: March 1, 2005
Abstract:
A single chip multiple range pressure transducer device including a wafer having a plurality of simultaneously formed thinned regions. The thinned regions are separated by a fixed portion, and each have a same minimum thickness. The thinned regions have at least one different planar dimension. A plurality of piezoresistive circuits are formed on the wafer. Each of the circuits is associated with and at least partially formed above one of the thinned regions. The thinnest regions deflect a different amount upon application of a common pressure thereto, whereby, when excited each of the circuits provides an output indicative the common pressure over a different operating range when the associated thinned region deflects.
Patent Title: Dual Beam Frequency-Output Accelerometer
Patent No.: US 6,848,307 B2
Date of Patent: February 1, 2005
Abstract:
There is described an accelerometer which is fabricated utilizing a beam diaphragm sensor employing dielectrically isolated resonant beams. Each resonant beam is subject to an acceleration. One beam is an acceleration sensing beam and contains a mass which is coupled to the deflecting diaphragm. As the accelerometer is subjected to acceleration, the acceleration sensing beam will alter its resonant frequency according to the applied acceleration, while the other beam is immune to acceleration and therefore, provides a relatively fixed resonant frequency. One then takes the difference frequency between the two beams to obtain an output frequency signal which is relatively independent of temperature and/or biasing changes.
Patent Title: Double Stop Structure For a Pressure Transducer
Patent No.: US 6,813,956 B2
Date of Patent: November 9, 2004
Abstract:
A stop member is secured to a piezoresistive semiconductor bossed diaphragm at the peripheral area, and includes a first and second slotted apertures in communication with the central active area, the fist and second slotted apertures correspond in location with opposing sides of a central boss. The stop member includes a stop cavity located between the first slotted aperture and the second slotted aperture, and the stop cavity overlies the central boss and is separated there-from to enable the diaphragm to deflect when a force is applied and to enable the central boss to impinge on the surface of the stop cavity when an excessive force is applied. The first and second slotted apertures permit another force to be applied to the active region of the diaphragm in the direction opposite to the stopped direction. A second stop member is secured to the diaphragm to provide stopping in either direction.
Patent Title: Solid State Fuel Cell Made From Porous and Partially Porous Semiconductor Structures
Patent No.: US 6,811,912 B2
Date of Patent: November 2, 2004
Abstract:
A solid state fuel cell is fabricated from three substructures. There is a porous anode made from n+ silicon which is surrounded by a non-porous ring. The pore size of the anode material is sufficiently large to allow hydrogen gas to flow through and is of sufficiently high conductivity to easily permit current flow of electrons. One side of the anode has enlarged pores and a layer of titanium and platinum is sputtered or otherwise deposited on the surface with the enlarged pores to produce a coated surface. A cathode is made in a similar manner and is fabricated as the anode. There is a center electrolytic section made from a low conductivity silicon or silicon carbide. The center electrolytic section has the coated side of the cathode secured to the other side. The other or un-coated face of both the anode and the cathode has an electrical contact secured thereto to permit electrons to leave the anode and to reenter the cathode. The electrolytic center structure is filled with an ionic conductor. In this manner, hydrogen is broken into ions and electrons. The electrons cause a current flow, while the ions react with oxygen and produce water which is discharged from the fuel cell as steam or vapor.
Patent Title: Dual Layer Color-Center Patterned Light Source
Patent No.: US 6,795,465 B2
Date of Patent: September 21, 2004
Abstract:
A thin layer of ionic crystal is grown on a substrate. The crystal could be any type of ionic crystal, such as sodium chloride or potassium chloride. The crystal is a pure form of the chosen compound and may contain contaminants which would shift the wavelength of created color centers. On top of the first crystal, a second thin layer of a different type of crystal is deposited, such as lithium fluoride or sodium fluoride. When these two layers are radiated with gamma rays, they will form color centers at the spots radiated. Because of the difference in crystalline properties of the two different ionic crystal centers, their color center would be at different wavelengths. Each of the two separate ionic crystals will emit light at different characteristic wavelengths when illuminated at their unique absorption frequencies. Each layer can be made to lase separately. The top layer has an absorption energy greater than that of the bottom layer, so that the layer energy of the bottom layer absorption peak will pass through the top layer and be absorbed only by the bottom layer. There are many ways of forming F-centers in the two superimposed layers, such as by the use of selective gamma radiation by heating of an anion layer of the particular compound and then depositing the second ionic crystal on the first ionic crystal and then depositing an anion layer on the second crystal and then heating to produce a structure which will lase it to the different frequencies.
Patent Title: P-N Junction Structure
Patent No.: US 6,727,524 B2
Date of Patent: April 27, 2004
Abstract:
There is disclosed a p-n junction diode structure whose electrical characteristics can be affected by the application of pressure or other mechanical stresses that will control sensitivity. The p-n junction consists of two different semiconductor materials, one being of p-type and the other of n-type, both having predetermined crystallographic axes which are fusion bonded together to form a p-n junction. Because of the ability to control the position of the crystallographic axes with respect to one another, one can affect the electrical characteristics of the p-n junction and thereby produce devices with improved operating capabilities such as Zener diodes, tunnel diodes as well as other diodes.
Patent Title: Pressure Transducer Employing On-Chip Resistor Compensation
Patent No.: US 6,700,473 B2
Date of Patent: March 2, 2004
Abstract:
A dielectrically isolated temperature compensated pressure transducer including: a wafer including a deflectable diaphragm formed therein, the diaphragm being capable of deflecting in response to an applied pressure, and the diaphragm defining an active region surrounded by an inactive region of the wafer; a plurality of dielectrically isolated piezoresistive elements formed on the active region of the wafer and coupled together to form a Wheatstone bridge configuration so as to cooperatively provide an output signal in response to and indicative of an amount of deflection of the diaphragm, the plurality of piezoresistive elements being undesirably operative to introduce an undesirable error into the output according to exposure of the water to an environmental condition; and, a dielectrically isolated resistor formed on the inactive region of the wafer and electrically coupled in series to the plurality of piezoresistive elements so as to at least partially compensate for the undesirable error.
Patent Title: Pressure Transducer Fabricated From Beta Silicon Carbide
Patent No.: US 6,691,581 B2
Date of Patent: February 17, 2004
Abstract:
A method for fabricating a dielectrically isolated silicon carbide high temperature pressure transducer which is capable of operating at temperatures above 600¡C. The method comprises applying a layer of beta silicon carbide of a first conductivity, on the first substrate of silicon. A layer of beta silicon carbide of a second conductivity is then applied on a second substrate. A layer of silicon is sputtered, evaporated or otherwise formed on the silicon carbide surfaces of each of the substrates of the beta silicon carbide. The sputtered silicon layer on each substrate is then completely oxidized forming a layer of SiO2 from the silicon. The first and second substrates are subsequently fusion bonded together along the oxide layers of the first and second substrate with the oxide layer providing dielectric isolation between the first and second wafers. This oxide layer, which is formed from the Si layer, has a much lower defect density than the SiO2 formed directly from the SiC. At least one sensing element is then fabricated from the beta silicon carbide of the second conductivity, and the overlaying original silicon on the second substrate is moved.
Patent Title: High Temperature Sensors Utilizing Doping Controlled, Dielectrically Isolated Beta Silicon Carbide (SIC) Sensing Elements On A Specifically Selected High Temperature Force Collecting Membrane
Patent No.: US 6,689,669 B2
Date of Patent: February 10, 2004
Abstract:
Semiconductor devices useful in high temperature sensing applications include a silicon carbide substrate, a silicon dioxide layer, and an outer layer of crystalline doped silicon carbide. The device is a 3CÐSiC/SiO2/SiC structure. This structure can be employed to fabricate high temperature devices such as piezoresistive sensors, minority carrier devices and so on. The crystalline doped silicon carbide is dielectrically isolated from the substrate. The devices are formed by processes that include bonding a pattern wafer to a substrate wafer, selective oxidation and removal of undoped silicon carbide. The level of doping and the crystalline structure of the silicon carbide can be selected according to desired properties for particular applications.
Patent Title: Static Pitot Transducer
Patent No.: US 6,688,182 B2
Date of Patent: February 10, 2004
Abstract:
A differential and absolute transducer are secured to a Pyrex glass header by means of a glass frit or other suitable interface. One of the sensors measures absolute pressure and the sensor is a sealed cavity, while the other sensor is designed to measure differential pressure and the sensor is an aperture which permits the pressure media to reach both sides of the sensor. The header itself has a through hole connected to a tube over which the differential sensor is affixed. The Pyrex glass is chosen to match the coefficient expansion of the sensor. The header in turn is attached to an adapter that enables static pressure to be applied to both sensors simultaneously and total pressure applied to the differential sensor, thus permitting the measurement of the difference between the total pressure and the static pressure. Each of the sensors is fabricated by the same processing techniques and is of the same thickness, but have different deflecting areas such that the differential sensor will have a greater stress through the same pressure. By obtaining both the differential and the static pressure, one can now determine air speed by the solution of BernoulliÕs theorem for a total pressure in compressible flow, such as through air or any other fluid.
Patent Title: Single Chip Multiple Range Pressure Transducer Device
Patent No.: US 6,642,594 B2
Date of Patent: November 4, 2003
Abstract:
A single chip multiple range pressure transducer device including a wafer having a plurality of simultaneously formed thinned regions. The thinned regions are separated by a fixed portion, and each have a same minimum thickness. The thinned regions have at least one different planar dimension. A plurality of piezoresistive circuits are formed on the wafer. Each of the circuits is associated with and at least partially formed above one of the thinned regions. The thinned regions deflect a different amount upon application of a common pressure thereto, whereby, when excited each of the circuits provides an output indicative the common pressure over a different operating range when the associated thinned region deflects.
Patent Title: Dielectrically Isolated Plastic Pressure Transducer
Patent No.: US 6,612,180 B1
Date of Patent: September 2, 2003
Abstract:
A pressure sensing device suitable for medical use including: a dielectrically isolated chip including a first wafer having first and second surfaces, a deflectable diaphragm formed therein and defining an active area of the sensor chip surrounded by an inactive area of the sensor chip, an electronic circuit formed on the first surface in the active area and being adapted to provide a signal indicative of an amount of deflection of the diaphragm, and a nonconductive coating on at least a portion of the second side; and, a plastic header including first and second ends, a recess in the first end and a plurality of electrically conductive pins extending from the recess through the header and out the second end; wherein, the sensor chip is secured within the recess of the plastic header such that the electronic circuit is in electrical contact with at least one of the pins.
Patent Title: Method and Apparatus For The Determination of Absolute Pressure and Differential Pressure Therefrom
Patent No.: US 6,612,179 B1
Date of Patent: September 2, 2003
Abstract:
A combination absolute and differential pressure sensing device including a plurality of absolute pressure transducers, each transducer including plurality of half bridge piezoresistive structures and a device for selectively coupling at least one of the plurality of half bridge piezoresistive structures of a first one of the absolute pressure transducers to at least one resistor to form a half-bridge full bridge structure adapted to measure an absolute pressure and at least one other of the plurality of half bridge piezoresistive structures of the first one of the plurality of absolute pressure transducers to at least one of the half bridge piezoresitive structure of a second one of the plurality of absolute pressure transducers to form a full bridge structure adapted to measure a differential pressure.
Patent Title: Leadless Metal Media Protected Pressure Sensor
Patent No.: US 6,612,178 B1
Date of Patent: September 2, 2003
Abstract:
In order to provide environmental protection, a leadless sensor of the type having a central boss is secured within a composite metal housing consisting of a top metal housing having a central boss which communicates with the central boss of the sensor. The top housing has a thin top portion surrounded by a peripheral portion, which peripheral portion is epoxied or otherwise secured to a bottom metallic housing having an internal hollow for accommodating the pressure sensor and the glass backing wafer, both of which are secured to a header which accommodates terminal pins associated with the active elements on the sensor device.
Patent Title: Force Transducer With Environmental Protection
Patent No.: US 6,601,455 B2
Date of Patent: August 5, 2003
Abstract:
A force transducer comprises a housing having a front and rear portions joined together by a platform, which platform is thinner than the housing portions. The platform contains at least one sensor which is operative to provide an output according to the extent of compression or expansion of the platform when a force is applied to the transducer housing. A compliant tubular member is secured at one end to the front portion of the housing. The compliant tubular member surrounds the sensor to protect the sensor from the surrounding environment. The tubular member expands and contracts compliantly with the applied force so that the sensor which is mounted on the platform is substantially unimpeded by the tubular member and provides an output directly proportional to the force applied to the housing.
Patent Title: Stopped Leadless Differential Sensor
Patent No.: US 6,595,066 B1
Date of Patent: July 22, 2003
Abstract:
A leadless sensor of the type employing a p+ rim which surrounds contact areas, each contact area defined by a metallized portion surrounded by a p+ semiconductor material, which p+ semiconductor materials or fingers are coupled to an active sensor array. The leadless sensor is bonded to a first glass cover member having two slotted apertures which communicate with the active regions of the sensor area on the underside and a top glass contact member which has two slotted regions which communicate with the piezoresistive sensors on the top side of the semiconductor wafer. The glass contact member has a series of corner through holes which are congruent with the contact terminals associated with the semiconductor sensor and which through holes are filled with a glass metal frit to enable contact to be made to the contact terminals of the semiconductor sensor. The contact glass member and cover member are electrostatically bonded to the silicon sensor at both sides of the sensor and have stop structures on both members to enable the sensor to receive a force or pressure in either direction. If the force in either direction exceeds a predetermined force, the silicon sensor will impinge against the surface of the stop area to limit the force and therefore prevent damage to the sensor. The sensor behaves as a differential sensor in operation where the Wheatstone Bridge sensor array provides a difference between the force applied to the top side of the sensor with respect to the force applied to the bottom of side of the sensor.
Patent Title: Closing of Micropipes in Silicon Carbide (SiC) Using Oxidized Polysilicon Techniques
Patent No.: US 6,593,209 B2
Date of Patent: July 15, 2003
Abstract:
In order to close or cover micropipes, which generally are formed in SiC bulk material, one sputters or deposits or grows a layer of silicon on the backside of a micromachined silicon carbide diaphragm. This is followed by an oxidation process. In this approach, the deposition of silicon reduces or completely plugs the micropipes. After the silicon deposition, the wafer is oxidized which completely closes the otherwise reduced micropipes. Since the oxidation process is significantly faster than silicon ns SiC, it is significantly easier to close even the largest of micropipes. The thickness of the silicon, the processing for depositing or growing silicon, and the process of oxidation can be adjusted to close micropipes in different SiC materials.
Patent Title: Oil Filled Pressure Transducer
Patent No.: US 6,591,686 B1
Date of Patent: July 15, 2003
Abstract:
An oil filled pressure transducer utilizes a leadless sensor which is secured to a header comprising a glass pre-form and a header shell. The glass pre-form contains holes which accept header pins and another aperture or hole which accepts the oil fill tube. The diameter of the sensor is chosen to be almost as large as the inner diameter of the shell. In this manner, there is a small cut out over the portion of the sensor that would otherwise cover the oil fill tube. The sensor is mounted to the header using glass bonds. There is a very small space between the outer diameter of the sensor and the inner diameter header housing, which is filled with glass used to mount the sensor. Since there are no ball bonds or gold wires in the area between the surface of the sensor and the diaphragm, the distance between the sensor and the metal diaphragm is drastically reduced, thereby substantially reducing the backpressure problem.
Patent Title: Double Stop Structure For a Pressure Transducer
Patent No.: US 6,588,281 B2
Date of Patent: July 8, 2003
Abstract:
A stop member is secured to a piezoresistive semiconductor bossed diaphragm at the peripheral area, and includes a first and second slotted apertures in communication with the central active area, the first and second slotted apertures correspond in location with opposing sides of a central boss. The stop member includes a stop cavity located between the first slotted aperture and the second slotted aperture, and the stop cavity overlies the central boss and is separated there from to enable the diaphragm to deflect when a force is applied and to enable the central boss to impinge on the surface of the stop cavity when an excessive force is applied. The first and second slotted apertures permit another force to be applied to the active region of the diaphragm in a direction opposite to the stopped direction. A second stop member is secured to the diaphragm to provide stopping in either direction.
Patent Title: Ultra High Pressure Transducers
Patent No.: US 6,577,224 B2
Date of Patent: June 10, 2003
Abstract:
An oil filled pressure transducer of the type employing a metal diaphragm has a diaphragm of a greater thickness than a conventional diaphragm. The thick diaphragm exhibits and accommodates extremely large pressures and deflects to cause a lower pressure to be transmitted to the oil. Because of the large thickness of the metal diaphragm, the diaphragm dissipates a predetermined percentage of the applied pressure, whereas a corresponding fraction of the applied pressure is transmitted to the oil and hence to the silicon sensors. In this manner the diaphragm acts as a step-down transformer where a portion of the force or pressure applied to the diaphragm is transmitted to the pressure sensor. The pressure sensor receives a pressure which is a fraction of the applied pressure and the sensor is compensated to produce an output proportional to the actual pressure as applied to the thick diaphragm.
Patent Title: High Temperature Surface Mount Transducer
Patent No.: US 6,564,644 B1
Date of Patent: May 20, 2003
Abstract:
There is disclosed a high temperature surface mounted pressure transducer. The pressure transducer consists of three basic parts which include an ultra thin surface mount sensor positioned on a borosilicate glass structure having four or more circular depressions which correspond to the contact areas of the semiconductor sensor with additional depressed lead-out channels. The lead-out channels and the contact depressions are metallized with a high temperature metallization system. The composite structure consisting of ultra thin surface mount sensor and borosilicate glass support structure is now mounted in a metallic flat-pack header or housing. In so mounting, the sensor is the first mounted to the glass structure using a metal glass frit in the contact depressions and as Pyroceram glass in the nonprotruding area of the sensor structure. The composite sensor metallized glass structure is then affixed to the metal structure, which is the metallic housing using an ultra high temperature solder such as indium gold or a low melting Pyroceram. The lead on the glass support plates are soldered to the leads on the flat-pack and the flat-pack can now be attached to any structure either by spot welding or by a suitable solder or other cement.
Patent Title: Pressure Transducer and Switch Combination
Patent No.: US 6,545,610 B2
Date of Patent: April 8, 2003
Abstract:
A device for providing a plurality of indications of a select pressure, said device including; an electronic interface having an input and an output; a restrictive structure adapted to measure the select pressure and being electrically coupled to the input of the electronic interface; a first output for providing a signal indicative of the select pressure, the first output being electrically coupled to the output of the electronic interface; and, a comparator coupled to the output of the electronic interface and being adapted to provide a signal indicative of whether the select pressure is greater than a predetermined threshold.
Patent Title: Wet-to-Wet Pressure Sensing Assembly
Patent No.: US 6,543,291 B1
Date of Patent: April 8, 2003
Abstract:
A wet-to-wet differential pressure sensing device including: a housing including first and second pressure receiving ports; a doubly stopped pressure sensor secured within the housing between the first and second ports; a first isolation diaphragm secured within the housing between the first port and the sensor; a second isolation diaphragm secured within the housing between the second port and the sensor; a first filling tube for introducing oil into a first cavity formed between the first diaphragm and the housing; and, a second filling tube for introducing oil into a second cavity formed between the second diaphragm and the housing; wherein the first and second filling tubes are accessible through a side wall of the housing being interposed between the first and second ports and the sensor and header are secured within the housing such that they are offset with respect to a center of the first diaphragm.
Patent Title: Ultra High Temperature Transducer Structure
Patent No.: US 6,530,282 B1
Date of Patent: March 11, 2003
Abstract:
A hermetically sealed high temperature pressure transducer assembly including: a sensor wafer that includes a plurality of sensor structures and contact areas selectively interconnected and formed on a surface thereof is provided. A first header assembly coupled to the sensor wafer includes a plurality of pins, each of which are electrically coupled to an associated contact area. A second header assembly is coupled to the first assembly and to a sleeve, and includes a plurality of tubes into each of which one of the plurality of pins is positioned. A temperature-insulated cable is partially positioned within the sleeve and includes a plurality of wires coupled to the pins. A third header apparatus is coupled to the sleeve and includes a plurality of closed-ended tubes for serving as leads, where each one of the plurality of wires is partially positioned in and coupled to a respective closed-end tube.
Patent Title: Force Transducer Assembly
Patent No.: US 6,446,510 B1
Date of Patent: September 10, 2002
Abstract:
A force transducer assembly for measuring compressive and tensile loads applied to a force transmission device, the assembly includes a housing, a sleeve assembly and a sensor device. The housing has a hollow interior. The sleeve assembly is coupled within the interior of the housing. The sensor device is secured within the interior of the housing between a portion of the sleeve assembly and a portion of the housing. The sensor device includes first and second sensors each including an isolation diaphragm at least partially defining an oil-filled cavity, and a piezoresistive sensor positioned so as to be effected by a change in pressure in the oil-filled cavity. When a first force is applied to the apparatus in a first direction via the force transmission device, one of the isolation diaphragms is deflectable in response thereto, and when a second force is applied in a second direction opposite to the first direction, the other of the isolation diaphragms is deflectable in response thereto. This causes a corresponding output from the sensor assembly. The first direction exerts a push on the device and the second direction exerts a pull on the device.
Patent Title: Silicon-On-Sapphire Transducer
Patent No.: US 6,424,017 B2
Date of Patent: July 23, 2002
Abstract:
A method for making silicon-on-sapphire transducers including the steps of forming a first silicon layer on a first side of a first sapphire wafer; bonding a second sapphire wafer to the first side of the first sapphire wafer such that the first silicon layer is interposed between the first and second sapphire wafers; reducing the thickness of the first sapphire wafer to a predetermined thickness; depositing a second silicon layer on a second surface of the first sapphire wafer, wherein the second surface of the first sapphire wafer is oppositely disposed from the first surface of the first sapphire wafer; bonding a silicon wafer to the second surface of the first sapphire wafer such that the second silicon layer is interposed between the first sapphire wafer and the silicon wafer, wherein the silicon wafer includes p+ regions indicative of a transducer structure and non-p+ regions; and, removing the non-p+ regions of the silicon wafer thus forming the transducer structure of p+ regions on the second surface of the first sapphire wafer.
Patent Title: Multiple Pressure Sensing System
Patent No.: US 6,401,541 B1
Date of Patent: June 11, 2002
Abstract:
A method for measuring multiple pressures and a pressure sensing system for accomplishing the same. The method for measuring a plurality of pressure includes, exposing each of a plurality of pressure sensors to a corresponding plurality of environments each having a corresponding pressure to be measured, determining how frequently to measure each of the plurality of pressures, determining a sequence for utilizing the pressure sensors to measure the corresponding plurality of pressures, the sequence being dependent upon the determined frequency for each of the plurality of pressures and selectively utilizing each of the plurality of pressure sensors according to the determined sequence to measure the pressure to which it is exposed.
Patent Title: Ultra High Temperature Transducer Structure
Patent No.: US 6,363,792 B1
Date of Patent: April 2, 2002
Abstract:
A hermetically sealed high temperature pressure transducer assembly including: a sensor wafer that includes a plurality of sensor structures and contact areas selectively interconnected and formed on a surface thereof is provided. A first header assembly coupled to the sensor wafer includes a plurality of pins, each of which are electrically coupled to an associated contact area. A second header assembly is coupled to the first assembly and to a sleeve, and includes a plurality of tubes into each of which one of the plurality of pins is positioned. A temperature-insulated cable is partially positioned within the sleeve and includes a plurality of wires coupled to the pins. A third header apparatus is coupled to the sleeve and includes a plurality of closed-ended tubes for serving as leads, where each one of the plurality of wires is partially positioned in and coupled to a respective closed-end tube.
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