Abstract: A piezoresistive sensor device and a method for making a piezoresistive device are disclosed. The sensor device comprises a silicon wafer having piezoresistive elements and contacts in electrical communication with the elements. The sensor device further comprises a contact glass coupled to the silicon wafer and having apertures aligned with the contacts. The sensor device also comprises a non-conductive frit for mounting the contact glass to a header glass, and a conductive non-lead glass frit disposed in the apertures and in electrical communication with the contacts. The method for making a piezoresistive sensor device, comprises bonding a contact glass to a silicon wafer such that apertures in the glass line up with contacts on the wafer, and filling the apertures with a non-lead glass frit such that the frit is in electrical communication with the contacts.

Abstract: A pressure transducer comprising a corrosion resistant metal diaphragm, having an active region, and capable of deflecting when a force is applied to the diaphragm; and a piezoresistive silicon-on-insulator sensor array disposed on a single substrate, the substrate secured to the diaphragm, the sensor array having a first outer sensor near an edge of the diaphragm at a first location and on the active region, a second outer sensor near an edge of the diaphragm at a second location and on the active region, and at least one center sensor substantially overlying a center of the diaphragm, the sensors connected in a bridge array to provide an output voltage proportional to the force applied to the diaphragm. The sensors are dielectrically isolated from the substrate.

Abstract: The RTD device of the present invention is comprised of a semiconductor substrate and a substantially thin conductive metal layer disposed upon the semiconductor substrate, wherein the conductive metal has a substantially linear temperature-resistance relationship. The conductive layer is etched into a convoluted RTD pattern, which consequently increases the overall resistance and minimizes the overall mass of the RTD assembly. A contact glass cover and a conductive metal-glass frit are placed over the RTD assembly to hermetically seal the RTD. The resultant structure can be “upside-down” mounted onto a header or a flat shim so that the bottom surface of the semiconductor substrate is exposed to the external environment, thus shielding the RTD from external forces. The resultant structure is a low mass, highly conductive, leadless, and hermetically sealed RTD that accurately measures the temperature of liquids and gases and maintains fast response time in high temperatures and harsh environments.

Abstract: An improved header assembly and corresponding port assembly comprising a tensioning member, wherein the tensioning member is isolated and separate from the weld portion and is adapted to place a threaded portion between the header assembly and port assembly in tension and maintain such tension, and thus relieve tension from the weld, before and after welding, thereby increasing the lifespan of the header and port assemblies.

Abstract: A system adapted to replace a mechanical switch with an electronic switch, without the need of additional wiring. The electronic switch includes a bridge array for sensing a characteristic, e.g., temperature or pressure, and an electronic circuit having a switch. As the characteristic of the bridge array varies a switch changes states.

Abstract: A piezoresistive sensor device and method for making the same are disclosed. The device comprises a silicon wafer having piezoresistive elements and contacts in electrical communication with the elements. The device further comprises a contact glass coupled to the silicon wafer and having apertures aligned with the contacts. The device also comprises a non-conductive frit for mounting the contact glass to a header glass, and a conductive non-lead glass frit disposed in the apertures and in electrical communication with the contacts. The method for making the device comprises bonding a contact glass to a silicon wafer such that apertures in the glass line up with contacts on the wafer, and filling the apertures with a non-lead glass frit such that the frit is in electrical communication with the contacts. The use of a lead free glass frit prevents catastrophic failure of the device in ultra high temperature applications.

Abstract: A gage/differential pressure transducer assembly having enhanced output capabilities, comprising a first pressure port adapted to communicate a first pressure to a first sensor, the first sensor comprising a first Wheatstone bridge adapted to output a first signal indicative of the first pressure, wherein the first pressure is a main pressure; and a second pressure port adapted to communicate a second pressure to a second sensor, the second sensor comprising a second Wheatstone bridge adapted to output a second signal indicative of the second pressure, wherein the second pressure is a reference pressure; and an output port connected to the first Wheatstone bridge and the second Wheatstone bridge for outputting a third signal representative of the difference between the first and second pressures.

Abstract: It is an objective of the present invention to provide a highly sensitive optical pressure sensor that uses a Mach-Zehnder Interferometer to measure pressure. The pressure sensor comprises a deflectable diaphragm including a substantially central boss and channel and an optical waveguide having a first arm and a second arm, 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, and further wherein the first and second arms contain a periodic array of etched holes to improve the overall sensitivity of the pressure sensor. The pressure sensor further comprises a light source coupled to the optical waveguide for introducing light to the waveguide and a light detector coupled to the waveguide for detecting changes in the intensity of light. The change in light intensity is then correlated to an applied pressure.

Abstract: There is disclosed a high temperature pressure sensing system which includes a SOI, silicon carbide, or gallium nitride Wheatstone bridge including piezoresistors. The bridge provides an output which is applied to an analog to digital converter also fabricated using SOI, silicon carbide, or gallium nitride materials. The output of the analog to digital converter is applied to microprocessor, which microprocessor processes the data or output of the bridge to produce a digital output indicative of bridge value. The microprocessor also receives an output from another analog to digital converter indicative of the temperature of the bridge as monitored by a span resistor coupled to the bridge. The microprocessor has a separate memory coupled thereto which is also fabricated from SOI, silicon carbide, or gallium nitride materials and which memory stores various data indicative of the microprocessor also enabling the microprocessor test and system test to be performed.

Abstract: A gas density transducer including: a piezoresistive bridge sensor operative to provide an output indicative of an applied pressure, a computing processor having multiple inputs and at least one output, with the output of the bridge sensor coupled to an input of the processor; a temperature sensor coupled to an input of the processor for providing at an output a signal indicative of a temperature of the bridge sensor, the output of the temperature sensor coupled to an input of the processor; and, at least one memory accessible by the processor and having stored therein: compensation coefficients for compensating the output of the bridge sensor for temperature variation; an algorithm for solving Van der Waal's equation; and, code for providing at an output of the processor a signal indicative of a gas density when the bridge is subjected to a gas containing environment.

Abstract: A semiconductor filter is provided to operate in conjunction with a differential pressure transducer. In one embodiment, a method comprises receiving, at a filter, a pressure, wherein the pressure includes a static pressure component and a dynamic pressure component; filtering, by the filter, at least the dynamic pressure component of the pressure; outputting, from the filter, a filtered pressure; receiving, at a first surface of a diaphragm, the pressure; receiving, at a second surface of the diaphragm, the filtered pressure, wherein the second surface of the diaphragm is operatively coupled to the filter; and measuring, at a sensor operatively coupled to the diaphragm, a difference between the pressure and the filtered pressure.

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.

Abstract: An enclosed, flat covered leadless pressure sensor assembly suitable for extreme environment operation including dynamic, ultra-high temperature heating, light and heat flash, and high-speed, flow-related environments. The pressure sensor assembly comprises a substrate comprising a micromachined sensing diaphragm defined on a first side. A cover is attached to the first side of the substrate such that it covers at least the sensing diaphragm. The top surface of the cover is substantially flat, thereby promoting uniformity in the distribution of stress and thermal effects across a top surface of the cover.

Abstract: There is disclosed a high pressure sensing header which is relatively insensitive to mounting torque. The header comprises an outer torque isolating shell which surrounds an inner “H” section header. The inner “H” section header has a thick diaphragm and is surrounded by the torque isolating shell which is secured to the “H” section header at a peripheral flange of the “H” section header. In this manner when the header is installed, the installation force is absorbed by the outer shell and there is no installation force or torque exhibited by the inner “H” section which will respond only to stress due to pressure. The torque isolating shell also contains a top surface which has a counterbore that accommodates a crush ring. When the unit is installed, the crush ring is crushed against an installation wall to enable the inner header to receive pressure without experiencing significant installation force.

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.

Abstract: A pressure transducer comprising a corrosion resistant metal diaphragm, having an active region, and capable of deflecting when a force is applied to the diaphragm; and a piezoresistive silicon-on-insulator sensor array disposed on a single substrate, the substrate secured to the diaphragm, the sensor array having a first outer sensor near an edge of the diaphragm at a first location and on the active region, a second outer sensor near an edge of the diaphragm at a second location and on the active region, and at least one center sensor substantially overlying a center of the diaphragm, the sensors connected in a bridge array to provide an output voltage proportional to the force applied to the diaphragm. The sensors are dielectrically isolated from the substrate.

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.

Abstract: There is disclosed a high pressure sensing header which is relatively insensitive to mounting torque. The header comprises an outer torque isolating shell which surround an inner “H” section header. The inner “H” section header has a thick diaphragm and is surrounded by the torque isolating shell which is secured to the “H” section header at a peripheral flange of the “H” section header. In this manner when the header is installed, the installation force is absorbed by the outer shell and there is no installation force or torque exhibited by the inner “H” section which will respond only to stress due to pressure. The torque isolating shell also contains a top surface which has a counterbore that accommodates a crush ring. When the unit is installed, the crush ring is crushed against an installation wall to enable the inner header to receive pressure without experiencing significant installation force.

Abstract: A piezoresistive sensor device and method for making the same are disclosed. The device comprises a silicon wafer having piezoresistive elements and contacts in electrical communication with the elements. The device further comprises a contact glass coupled to the silicon wafer and having apertures aligned with the contacts. The device also comprises a non-conductive frit for mounting the contact glass to a header glass, and a conductive non-lead glass frit disposed in the apertures and in electrical communication with the contacts. The method for making the device comprises bonding a contact glass to a silicon wafer such that apertures in the glass line up with contacts on the wafer, and filling the apertures with a non-lead glass frit such that the frit is in electrical communication with the contacts. The use of a lead free glass frit prevents catastrophic failure of the device in ultra high temperature applications.

Abstract: A two or three axis load cell capable of measuring axial and one or more shear forces is disclosed. The load cell can comprise a force collector connected by one or more connecting rods to one or more cross pieces. The load cell can comprise a single cross piece and can measure an axial force applied to the load cell and at least one component of shear force applied to the load cell. In other embodiments, the load cell can comprise two cross pieces, disposed at disparate angles, to enable the measurement of an axial force and both components of shear force applied to the force collector. The cross pieces are equipped with a means, such as piezoresistive elements to measure their deflection due to the applied forces on the force collector. The connecting rods can be fitted with additional piezoresistors to measure the axial forces on the force collector.