Abstract: A pressure sensor has a case having a first side and a second side, and a sensing portion mounted to the case. A first diaphragm is disposed on the first side of the case such that a first chamber is defined. A second diaphragm is disposed on the second side of the case such that a second chamber is defined. The first chamber and the second chamber are filled with a pressure medium such as an oil. The case forms an introduction passage for introducing the pressure medium into the first chamber and the second chamber. In a condition that the first chamber and the second chamber are filled with the pressure medium, the introduction passage is sealed by a sealing part so that the first chamber and the second chamber are separated from each other and from an outside of the case.

Abstract: A differential pressure indicator and method of configuring a differential pressure indicator is provided. The differential pressure indicator is configurable to provide open circuit or closed circuit logic and includes a housing, a pressure responsive element, a post, first, second and third electrical contacts and an electrical insulator from an insulative material. The electrical insulator separates the third electrical contact from either the first contact or the second contact to provide a desired type of logic. The differential pressure indicator may use substantially similar components to provide either open circuit or closed circuit logic or the components may be rearranged to provide either open circuit or closed circuit logic.

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.

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.

Abstract: The invention relates to a device and a method for the status monitoring of a pressure measuring unit in an absolute or differential or relative pressure transducer, a pressure-sensitive element installed in the pressure measuring unit being impinged with at least one pressure generated by at least one membrane. During a defined diagnosis time interval, a testing element integrated in the pressure measuring unit is induced to undergo a change in volume, preferably by electrical activation. The pressure difference caused as a result in the pressure measuring unit is registered by a pressure-sensitive element. The curve registered during a diagnosis time interval is compared with a reference curve recorded with the pressure measuring unit intact. A fault indication is given if the deviations between the registered curve and the reference curve exceed predetermined tolerance values.

Abstract: A pressure-difference sensor, which is asymmetrical by design, includes a measuring apparatus having a first half-chamber with a first volume V1, which is sealed by a first separating membrane having a first membrane stiffness E1, and a second half-chamber with a second volume V2, which is sealed by a second separating membrane having a second membrane stiffness E2, wherein the first half-chamber is separated from the second half-chamber by a pressure sensitive element, especially a measuring membrane, and the first half-chamber is filled with a first transfer liquid having a first coefficient of thermal expansion ?1 and the second half-chamber is filled with a transfer liquid having a second coefficient of thermal expansion ?2.

Abstract: A pressure pickup, having a pressure chamber, which is located between a separating membrane and a platform. A pressure canal for hydraulic transmission of pressure to a measuring cell, includes, for dynamic overload protection, a Venturi throttle implemented by providing that the pressure canal has at least one segment whose flow cross section is variable. Such segment is preferably provided in the form of an annular canal. The flow cross section can be changed, for example, by an axial shifting of a conical inner wall relative to a complementary, conical outer wall, or by the deforming of an elastic inner or outer wall of the annular canal.

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.

Abstract: A pressure gauge includes a diaphragm having a substantially rigid outer portion and a displaceable inner portion that displaces in response to a pressure difference between first and second sides of the diaphragm. The pressure gauge further includes a sensor located proximate to the diaphragm and adapted to sense the displacement of the diaphragm inner portion. The pressure gauge further includes a monitor and control system coupled to the sensor (wired or wireless), and adapted to determine the pressure difference from the displacement of the diaphragm. The sensor and the monitor and control system can be implemented with one or more optical sensing designs, capacitive sensing designs, or other devices used to measure sub-micron displacements. For low pressure applications, such as lithography applications, the diaphragm is sensitive to pressure changes in a range of approximately 0.1 to 0.5 inches of water.

Abstract: A diaphragm pressure sensor includes a first insulating substrate, a conductive substrate with a diaphragm, and a second insulating substrate with a gas inlet are bonded so as to form a pressure reference room between the diaphragm and the first insulating substrate and a pressure measuring room between the diaphragm and the second insulating substrate. The deformation of the diaphragm caused by the pressure difference between the pressure measuring room and the pressure reference room is measured to obtain the pressure of a space which is communicated with the pressure measuring room through the gas inlet. Furthermore, a plate is adhered to a surface of at least one of the first and second insulating substrates and the plate has a lower thermal expansion rate in an ambient temperature than that of the insulating substrate to which the plate is adhered.

Abstract: An isolation assembly for connection to a process transmitter and for mitigating high temperature effects of a process fluid includes a process coupling face having an isolation diaphragm configured to contact process fluid. A transmitter coupling has a pressure coupling configured to couple to a pressure port of the process transmitter. A temperature isolation fluid conduit extends between the process coupling face and the transmitter coupling and carries an isolation fluid which couples a pressure applied to the isolation diaphragm to the pressure coupling to minimize high temperature effects of the process fluid on the process transmitter.

Abstract: This invention relates to absolute pressure sensors with two bonded wafers containing a pressure sensing structure and forming a reference pressure chamber and a buffer chamber. Since the buffer chamber collects molecules, which permeate through a bonding interface between the two wafers, a raise in pressure of the reference chamber can be avoided. The sensor is therefore more resistant to pressure equalisation between the pressure chamber and the pressure of the surroundings, i.e. the sensed pressure and repetitive recalibration of the sensor can be avoided.

Abstract: A relative pressure sensor comprises two chambers and two separating membranes respectively provided for a process pressure and an ambient pressure. The chambers are separated by a pressure-sensitive element and are filled with a transmission medium. In order to attenuate process-side overload pulses, which act upon the first separating membrane, a hydraulic damper is provided that is placed on the side of the atmosphere between the second separating membrane and the pressure-sensitive element. The pressure-sensitive element is a piezoresistive silicon chip, the transmission medium consists of silicone oil, and the damper is comprised of a filter element made of sintered bronze having 29% porosity and an 11 micrometer pore diameter. The filter element has a length of 8 mm and a diameter of 2 mm.

Abstract: A pressure sensor (30) for sensing a fluid pressure in harsh environments such as the air pressure in a tire, by using a first wafer substrate (32) with a front side and an opposing back side, a chamber (58) partially defined by a flexible membrane (50) formed on the front side and at least one hole (33) etched from the back side to the chamber (58); a second wafer (31) on the back side of the first wafer (32) to seal the at least one hole (33); wherein, the chamber (58) containing a fluid at a reference pressure, such that the flexible membrane (50) deflects due to pressure differentials between the reference pressure and the fluid pressure; and, associated circuitry (34) for converting the deflection of the flexible membrane (50) into an output signal indicative of the fluid pressure; wherein, the second wafer (31) is wafer bonded to the first wafer substrate (32). Wafer bonding offers an effective non-adhesive solution.

Abstract: Disclosed is a pressure measuring system for a vacuum chamber, in particular, a pressure measuring system for a vacuum chamber using ultrasonic wave. In this regard, there is provided a pressure measuring system for a vacuum chamber using ultrasonic wave, comprising a vacuum chamber 10 formed with desired vacuum at the inside thereof; ultrasonic wave-emitting means mounted close to an outer peripheral surface of the vacuum chamber 10 for emitting an ultrasonic wave 62 to the inside of the vacuum chamber 10; ultrasonic wave-receiving means for receiving a reflection wave 64 reflected after the striking of the ultrasonic wave 62 emitted from the ultrasonic wave-emitting means to the vacuum chamber; reflection wave-detecting means for detecting the reflection wave 64 from the ultrasonic wave-receiving means; and amplitude-analyzing means for analyzing the amplitude of the reflection wave 64 detected by the reflection wave-detecting means.

Abstract: According to the present invention, there is provided a high-precision differential pressure sensor which is not affected by a considerable change in baseline pressure. A differential pressure sensor of the present invention includes: a pair of diaphragms, each including a diaphragm portion capable of being deformed due to application of a pressure and a support portion for holding an outer peripheral edge of the diaphragm portion; a pair of fixed electrodes in disk-like form fixed to the support portions of the diaphragms; and a movable electrode including a disk-like electrode portion and shaft-like projections extending in opposite directions from a central portion of the electrode portion. The shaft-like projections extend at a right angle relative to the electrode portion, and the movable electrode is secured to central portions of the diaphragms through the shaft-like projections so that the electrode portion faces each of the fixed electrodes in a predetermined spaced relationship.

Abstract: Pressure transducers are used to measure pressure under high temperature, hostile environments, including in gas turbine combustors and internal combustion engines. The present a pressure transducer comprises a member having a first end and a second end, a diaphragm sealed within the member at the first end, a sensor sealed within the member at the first end and in operable communication with the diaphragm, a first plate having a plurality of apertures, the first plate being attached to the member at the second end, a second plate having a plurality of apertures, the second plate being attached to the tubular member at the second end and being spaced from the first plate, and wherein the apertures of the first plate are not aligned with the apertures of the second plate.

Abstract: It is related to the shape of a back surface formed to allow a pre-loading diaphragm to become deformed at a threshold pressure value. A differential pressure measuring apparatus has the pre-loading diaphragm which becomes deformed to prevent sensors from being broken when pressure higher than a threshold pressure value is applied, wherein only convex parts of the pre-loading diaphragm are in close contact with convex parts of the back surface of a body respectively.

Abstract: The ultra-precision micro-differential pressure measuring device comprises a device body 1 having an inner space part therein, a pressure receiving plate 3 which is installed inside the inner space of the device body 1 and divides the said inner space hermetically into a lower space 7 and an upper part space 8, an electronic weighing and pressure converting device 2 which is installed in the lower space 7, and supports and secures the pressure receiving plate 3, and a liquid sealing part R which liquid-seals the outer peripheral part of the aforementioned pressure receiving plate 3 and maintains the air-tightness between the lower space 7 and the upper space 8. A micro-differential pressure between a pressure P1 inside the upper space 8 and a pressure P2 inside the lower space 7 is measured by the electronic weighing and pressure converting device 2 through the pressure receiving plate 3.

Abstract: A pressure-measuring device is configured for use in vacuum systems, which are used for surface coating or modification of objects and/or substrates in an inner receptacle inside a processing chamber. Elastic elements or portions are fabricated in the inner receptacle. The pressure-measuring device includes distance-measuring elements designed to measure the deformation of the elastic elements of the inner receptacle. The deformation measurements are related to the pressure in the inner receptacle. The pressure-measuring device provides a continuous and secure determination of the pressure.

Abstract: A pressure sensor is provided incorporating a first chamber having a first flexible membrane exposed to fluid pressure and configured to deflect in response to changes in the fluid pressure and temperature within the first chamber, a second chamber having a second flexible membrane sealed from the fluid pressure and configured to deflect in response to changes in temperature within the second chamber, and associated circuitry for comparing the deflection of the first and second membranes to sense the fluid pressure.

Abstract: A fiber optic differential pressure sensor. In a described embodiment, a differential pressure sensor system for use in a subterranean well includes a fluid property sensing housing having a flow passage formed therethrough. A differential pressure sensor has an optical fiber extending in a wall having a first side and a second side, each of the first and second sides being exposed to pressure in the flow passage.

Abstract: A differential pressure detection type pressure sensor includes: a casing having a concavity; a pressure detection element disposed on a bottom of the concavity; a through hole; a first protection member in the concavity; and a second protection member in the through hole. The pressure detection element has one side facing the bottom of the concavity and the other side facing an opening of the concavity. The through hole includes one opening on the bottom of the concavity and the other opening on a part of the casing. The height of the first protection member facing the opening of the concavity and the height of the second protection member in the other opening of the through hole are on a same plane.

Abstract: A disposable pressure sensor includes a substrate and a pressure diaphragm formed upon the substrate. A sensor coil can be provided, comprising a capacitor and an inductor formed on the substrate and surrounded by the pressure diaphragm. The ferrite core is located proximate to the sensor coil, such that when the pressure diaphragm is exposed to a pressure, the diaphragm moves close to the inductor or the capacitor, thereby resulting in a change in the capacitor or the inductor and an indication of pressure. The capacitor can be implanted as an adjustable, trimmable or variable capacitor. The inductor may also be provided as an adjustable or variable inductor and can include the use of a variable capacitor and a PVDF based piezoelectric transducer. When the PVDF layer is under pressure, it can generate an electric field across the interdigital transducer and transmit a signal thereof through an antenna.

Abstract: A pressure sensor for measuring a pressure difference between a pressure being measured and the ambient atmospheric pressure surrounding the pressure sensor, including a platform and a membrane loadable with a pressure being measured. The membrane is secured at its edge to the platform, with a pressure chamber thus being formed between the platform and the measuring membrane. The pressure chamber communicates over a reference air path with the atmosphere, with the reference air path being a winding path.

Abstract: A differential pressure transducer which incorporates a Fabry-Perot sensor for direct quantitative measurements of the distance displaced by a piston abutting two pressure boundaries is described. The apparatus includes a piston with an annular protrusion which is fitted into a transducer housing having a peripheral groove that serves as a stop to prevent damage to the in overpressure situations. A method of measuring differential pressure using a Fabry-Perot sensor is also contemplated.

Abstract: A pressure transmitter for transfer of a pressure prevailing in a first medium onto a second medium, including a pressure chamber 4 in a platform 1, which chamber is separated from the first medium by means of a dividing membrane 2, wherein the pressure can be transferred by means of the second medium to a pressure measurement cell. For timely recognition of an impending failure of the dividing membrane, an early warning detector is provided with a sensor chamber 6 having an opening, which faces the first medium; and a sensor 7, which monitors a property of a medium container in the sensor chamber; and a barrier facing the first medium, pressure-tightly sealing the opening, and which, under contact with the first medium and equal conditions as experienced by the dividing membrane 2, fails earlier than the dividing membrane, thus making possible a flow connection between the sensor chamber 6 and the first medium.

Abstract: A pressure sensor (30) for sensing fluid pressure in harsh environments such as the air pressure in a tire by providing a chamber (58) partially defined by a flexible membrane (50). The flexible membrane (50) is at least partially formed from conductive material, and the chamber (58) contains a fluid at a reference pressure. The flexible membrane (50) deflects from any pressure difference between the reference pressure and the fluid pressure. A conductive layer (36) within the chamber spaced from the flexible membrane (50) and, associated circuitry (34) incorporating the flexible membrane (50) and the conductive layer (36). The conductive layer (36) and the flexible membrane (50) form capacitor electrodes and the deflection of the flexible membrane (50) changes the capacitance which the associated circuitry (34) converts into an output signal indicative of the fluid pressure.

Abstract: A pressure sensor (30) for sensing a fluid pressure in harsh environments such as the air pressure in a tire, by using a chamber (58) partially defined by a flexible membrane (50), the flexible membrane (50) is a laminate having at least two layers wherein at least one of the layers is at least partially formed from conductive material, and the chamber (58) containing a fluid at a reference pressure, such that the flexible membrane (50) deflects from any pressure difference between the reference pressure and the fluid pressure; and, associated circuitry (34) for converting deflection of the flexible membrane (50) into an output signal indicative of the fluid pressure. Forming the membrane from a number of separately deposited layers alleviates internal stress in the membrane (50). The layers can be different materials specifically selected to withstand harsh environments.

Abstract: A pressure sensor (30) for harsh environments such as vehicle tires, formed from a chamber (58) partially defined by a flexible membrane (50), the chamber (58) containing a fluid at a reference pressure. In use, the flexible membrane (50) deflects from any pressure difference between the reference pressure and the fluid pressure. The membrane (50) being at least partially formed from conductive material so that associated circuitry (34) converts the deflection of the flexible membrane (50) into an output signal indicative of the fluid pressure. The flexible membrane is less than 3 microns thick to allow the use of a high yield strength membrane material. A thinner membrane also allows the area of the membrane to be reduced. Reducing the area of the membrane reduces the power consumption and the overall size of the sensor. A high yield strength material is better able to withstand the extreme conditions within the tire and a compact design can be installed in restricted spaces such as the valve stem.

Abstract: A pressure sensor that compensates for variations in temperature by having first (53) and second (51) chambers with first and second respective flexible membranes. The first and second flexible membranes deflect in response to pressure differences within the first and second chambers respectively. The first membrane is exposed to the fluid pressure (66) to be measured, such as the air pressure in a tire. The second membrane sealed from the fluid pressure, and, associated circuitry converts the deflection of the first flexible membrane into an output signal related to the fluid pressure, and converts the deflection of the second membrane into an adjustment of the output signal to compensate for the temperature of the sensor. By sealing the second chamber from the tire pressure, the deflection of the second membrane can be determined as a function of temperature. This can be used to calibrate the output signal from the first chamber to remove the effects of temperature variation.

Abstract: The present invention provides a small-sized electrostatic condenser type pressure sensor having high assembly accuracy but no dispersion in a detection accuracy, and a method for manufacturing the pressure sensor. An annular spacer is mounted on the confronting faces of substrates around flat electrodes, and a frit is mounted around the spacer and is made of a material having a lower softening or melting point than that of the spacer.

Abstract: Differential pressure sensor systems and methods are disclosed, including an absolute pressure sensor composed of a plurality of pressure sense die for detecting sensed media, wherein each of the pressure sense die possess a back side and a front side and are respectively associated with a plurality of varying pressures. The sensed media are applied only at the backside of the pressure sense die, thereby preventing wire bonds and active regions associated with the front side of the pressure sense die from exposure to sensed media and attack from acids and abrasive chemicals associated with the sensed media.

Abstract: A manometer integrated into a manual resuscitator includes a housing with a communication path, and a pressure gauge integrally forming part of the housing. A sensing chamber and an atmospheric chamber are separated by a diaphragm subject to distortion by differential pressure between the chambers, with a spring to restore the diaphragm upon equalization of the pressures. A shaft journaled in a first bearing on the diaphragm and a second bearing in one of the chambers rotates in the bearings upon diaphragm distortion, and an indicator on the shaft indicates differences in pressure between the chambers.

Abstract: The invention provides a system and a method for generating high pressure hydrogen that is able to efficiently and safely generate hydrogen by only the electrolysis of water even when using electric power generated by a frequently varying natural energy, such as sunlight, without using any compressors. The system comprises an electrolysis cell using polyelectrolyte membranes, particularly a double-polarity multi-layered type electrolysis cell having a specified structure disposed in a vessel for storing generated hydrogen, preferably for storing cooled hydrogen under a high pressure hydrogen atmosphere. High pressure hydrogen is generated by electrolysis of pure water using the electrolysis cell by suppressing the pressure applied to the cell to a pressure below the pressure resistance of the cell using a differential pressure sensor and pressure controller.

Abstract: A differential pressure sensor includes a measuring mechanism having a chamber on the high-pressure side that is sealed by a first dividing membrane, and a chamber 6 on the low-pressure side that is sealed by a second dividing membrane. The first dividing membrane is loadable with a pressure acting on the high-pressure side and the second dividing membrane with a pressure acting on the low-pressure side, and the chamber on the high-pressure side is separated from the chamber on the low-pressure side by a pressure-sensitive element, especially a measuring membrane, and the chambers of the high- and low-pressure sides are filled with a transfer medium. For damping of overload pulses acting on the first dividing membrane on the high-pressure side, a hydraulic throttle is provided, which is arranged on the low-pressure side between the second dividing membrane and the pressure-sensitive element.

Abstract: A differential pressure sensor for use in an industrial application is described. The differential pressure sensor includes a membrane layer having a covered portion and an exposed portion where a first side of the exposed portion of the membrane layer is in fluid communication to a first aperture and a second side of the exposed portion is in fluid communication to a second aperture. The differential pressure sensor also includes at least one resonating device secured to the covered portion of the membrane layer and configured to oscillate at a desired frequency and a sensing circuitry configured to a detect oscillation in the at least one resonating device indicative of deformation in the membrane layer.

Abstract: The differential pressure sensor is formed of a semiconductor substrate (1) which is thinned out in an inner region into a membrane (2) which may be impinged by pressure on both sides. Measurement resistances (3a to 3d) for detecting the differential pressure (P1 minus P2) are formed within the membrane (2), and compensation resistances (4) are formed on the carrier, which are connected to measurement resistances (3). The measurement resistances (3) are connected into a first measurement bridge (6) and the compensation resistances (4a to 4d) into a second measurement bridge (7).

Abstract: A system for air pressure electric switch adjustment comprises a frame. A pressure port is mounted to the frame for connection to a source of fluid under pressure to be monitored. An actuator is movably mounted relative to the frame responsive to fluid pressure at the pressure port. A switch includes a fixed contact and a movable contact. The fixed contact is fixedly mounted relative to the frame. A differential mechanism comprising a pair of linked levers is hingedly mounted to the frame. One of the linked levers is driven by the actuator. The other lever carries the movable contact. A snap spring links the two levers so that the other lever is normally in a first position with the switch in a normal state. The other lever is toggled responsive to pivotal movement of the one lever by the snap spring to a second position with the switch in an actuated state.

Abstract: A device for measuring pressure includes a housing 9 in which a carrier 3 equipped with a sensor element 31 and electrical connection elements 34 is located. The housing 9 is made up of a first housing chamber 4 that encloses the sensor element 31 and is connected with a first pressure channel 13 of a first pressure connection 12. The housing also includes a second housing chamber 5 that is sealed off from the first housing chamber 4 and encloses at least the electrical connection elements 34. The housing 9 has a third housing chamber 6 that is sealed off from the first housing chamber 4 and the second housing chamber 5. The third housing chamber is connected with a second pressure channel 11 of a second pressure connection 10.

Abstract: A semiconductor component for a semiconductor substrate, in which a first section and a second section are provided, and in which the pore structure of the first section differs from the pore structure of the second section.

Abstract: A system for monitoring the condition of impulse lines to a differential pressure sensor. The lines may be connected at two locations of a pressure source, such as a pipe having a fluid flow. One line may direct a pressure of the source to one side of a piezoelectric diaphragm and another line may direct another pressure to the other side of the piezoelectric diaphragm. The diaphragm may provide an electrical indication of the differential pressure between both sides of the diaphragm. One of the lines may also be connected to a piezoelectric diaphragm of a static pressure sensor. The latter diaphragm may provide an electrical indication of static pressure. Detection and comparison of noise levels of the electrical indications of the pressures may indicate if one or both lines are plugged, and which one if not both.

Abstract: A well pressure and temperature measurement system and method are provided. In a described embodiment, a sensor system includes multiple strain sensors attached to a structure which changes dimensionally in response to well pressure and temperature changes. The strain sensors may be fiber optic sensors. The structure may be tubular and the strain sensors may detect axial and hoop strains in the structure.

Abstract: In a differential pressure sensor, the measurement value is corrected with the help of the nominal pressure NP. In this way, influences on the measurement value because of deformations of the body of the differential pressure sensor and change in the material stiffness of the membrane are decreased.

Abstract: A pressure measurement device comprising an absolute pressure sensor and a bus coupling serial communication and energization to an electrical connector in a field wiring compartment. An atmospheric pressure sensor module is connected to the bus at the electrical connector. The bus provides the energization to the atmospheric pressure sensor module and the bus receives a serial communication signal from the atmospheric pressure sensor module. The serial communication signal includes numeric data representing atmospheric pressure. The pressure measurement device provides a gage pressure output as a calculated difference between the sensed absolute pressure and the received numeric data.

Abstract: This invention relates to a differential pressure sensor, one embodiment of which is a microphone. The differential pressure sensor comprises: a flexible membrane (7) made of conductive material, which membrane forms a first electrode of the differential pressure sensor, and a perforated plate (6) made of conductive material, which plate is essentially more rigid than said membrane (7), which plate is arranged at a distance from the membrane, and which plate forms a second electrode of the differential pressure sensor. In order to provide a differential pressure sensor with as good properties as possible, the differential pressure sensor comprises a substrate (4), a cavity (10) extending through the substrate, the walls of which cavity are formed of said substrate (4). The membrane (7) is closely connected to the walls of the cavity (10), whereby the membrane forms a dense wall in said cavity, and said perforated plate (6, 6?) has been attached to the substrate with an insulating layer (5).

Abstract: A pressure sensing device for measuring the pressure of a fluid, comprising: a measurement diaphragm which is at least partially made of semiconductor material, is provided with a first surface and a second surface which are exposed respectively to a first pressure and to a second pressure, and undergoes a deformation following the application of the first pressure and of the second pressure; and a resonant element made of semiconductor material which is provided with a first end portion and with a second end portion for mechanically coupling the resonant element to the measurement diaphragm, the oscillation frequency of the resonant element varying according to the deformation to which the measurement diaphragm is subjected; and first circuit means for generating a sensing signal which is indicative of the oscillation frequency of the resonant element.

Abstract: A system is described for controlling the flow of a sample fluid through a substrate having first and second surfaces and at least one area with a plurality of through-going capillary channels. The system comprises a housing having a chamber for receiving the substrate and a pressure differential generator capable of generating and maintaining a pressure difference over the substrate.

Abstract: A device and method for signaling differential pressure change occurring during leak testing of an evaporative emission control space in a motor vehicle fuel system. A casing has sensing ports one of which is communicated to a reference pressure, such as atmospheric pressure, and another of which is communicated to sense pressure in the evaporative emission control space. As difference between the reference pressure and the pressure in the control space changes, the net magnetic flux acting on a magnetoresistive sensor changes. The sensor is electrically connected to the vehicle electrical system for signaling the differential pressure. The device may be used for both positive and negative pressure leak testing.

Abstract: A differential pressure sensor for sensing changes in pressure at a desired location, which sensor includes a sensing portion and a reference portion to produce an output indicative of the difference therebetween, both the sensing portion and the reference portion being open to the pressure around the sensor until the sensor is located in the desired sensing location and then the reference portion is closed to capture the pressure then existing at the desired location and any pressure changes thereafter producing signals indicative of the pressure differences.