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: Exemplary embodiments of the present invention provide a differential pressure transducer that comprises first and second diaphragms of different configurations, i.e., different diameters and/or thicknesses. The pressure transducer provides more versatility over prior art designs as the diaphragms can be of different configurations yet still maintain substantially similar back pressures. Therefore, the errors commonly associated with back pressures are eliminated because the back pressures from the diaphragms ultimately cancel out in the sensor's differential pressure measurement.

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 dual diaphragm pressure transducer, or sensor, with compensation for non-pressure effects is disclosed. The pressure sensor can include two pressure transducers located on separate portions of a chip. The first pressure transducer can be a differential pressure transducer, which produces a signal proportional to one or more applied pressures and includes other non-pressure effects. The second pressure transducer can be sealed in a hermetic chamber and thus can produce a signal proportional only to non-pressure effects. The signals can be combined to produce a signal proportional to the applied pressures with no non-pressure effects. The first and second pressure transducers can be physically and/or electrically isolated to improve sealing between the two pressure transducers and prevent pressure leaks therebetween.

Abstract: There is disclosed an internally switched multiple range transducer. The transducer employs a plurality of individual pressure sensors or Wheatstone bridges fabricated from semiconductor materials and utilizing piezoresistors. Each sensor is designed to accommodate accurately a given pressure range, therefore, each sensor is selected to provide an output when an applied pressure is within its accommodated range. As soon as the pressure exceeds the range, then another sensor is employed to produce an output. Each of the sensors, or each separate transducer, is coupled to a switch or other device to enable the selection of one of the plurality of sensors to operate within its given pressure range when the applied pressure is in that range. In this manner one obtains pressure measurements with a high degree of accuracy across a relatively large pressure range.

Abstract: Embodiments of an ultra miniature pressure probe are disclosed. The pressure probe can include a probe body, a plurality of transducer ports, and a plurality of transducers. The probe body can be a longitudinal tubular body having a front conical end. The transducer ports can be disposed about the front end of the body. The transducers can be leadless SOI transducers, each having an active deflection area associated with a semiconductor substrate. Each transducer can be in communication with a header for supporting the transducer. The header can have a thickness substantially less than the probe diameter and can comprise a flange about an edge of the header. Each of the plurality of transducer ports can define an aperture and a counter-bore, wherein each transducer is positionable in an associated transducer port with the flange of the header of the transducer being welded to the counter-bore of the transducer port.

Abstract: A system for measuring a multiplicity of pressures as those experienced by a model in a wind tunnel is depicted. The system includes individual sensor devices which are connected to an electronics module. The sensors may be connected to the electronics module via a cable in a first embodiment. In an alternate embodiment, the sensors may be connected to the electronics module via a mating connector located therebetween. A memory component which stores compensation coefficients associated with each of the sensors may also be included in the system to correct errors associated with each sensor. The advantage of the various embodiments is that each sensor does not have any compensation stored thereon and thus, the sensors can be made very small to operate at very high temperatures without any loss of accuracy.

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 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 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: 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: There is disclosed a high temperature pressure sensing system which includes a SOI Wheatstone bridge including piezoresistors. The bridge provides an output which is applied to an analog to digital converter also fabricated using SOI technology. 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 technology and which memory stores various data indicative of the microprocessor also enabling the microprocessor test and system test to be performed.

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.

Abstract: A gage pressure transducer comprising a first pressure sensing assembly exposed to a main pressure and a second pressure sensing assembly exposed to a reference pressure. The pressure sensing assemblies comprise half-bridge sensors and means for using an alignment glass plate with each sensor which reduces the amount of oil required for operation, which consequently reduces the back pressures caused by large volumes of oil. The pressure sensor assemblies are hermetically sealed using glass frits, therefore enabling the gage pressure transducer to robustly and accurately measure pressure in harsh environments.

Abstract: An oil-filled pressure transducer having reduced back pressure, comprising an alignment plate having a sensor accommodating aperture, a sensor module inserted into the sensor accommodating aperture, a header surrounding the alignment plate, the header having a protruding top surface, and a diaphragm disposed on the protruding top surface to create a relatively small oil accommodating region between the diaphragm and the sensor. This configuration reduces the oil volume required for operation, which ultimately reduces the back pressure applied against the diaphragm.