Abstract: Techniques for determining at least one downhole parameter of a wellsite are provided. A sensor apparatus is operatively connectable to a downhole tool deployable into a borehole of the wellsite, the downhole tool having a conduit system for receiving downhole fluid. The sensor apparatus has a housing, at least one gauge, a gauge carrying body positionable in the housing for receiving the gauge, and a flowline extending through the gauge carrying body for operatively connecting the conduit system to the gauge whereby parameters of the downhole fluid are measured. The gauge has at least one pressure sensor and at least one temperature sensor. The gauge carrying body has a pressure resistant block and a thermal absorber positionable about the gauge.

Abstract: A tunable pressure transducer assembly that comprises a sensing element disposed within a housing, wherein the sensing element is adapted to output a signal substantially indicative of an applied pressure, and a filter assembly also disposed within the housing. The filter assembly comprises a cap and a tube, wherein the cap is spaced from the sensing element within the housing such that it encloses a set volume around the sensing element, and wherein the tube controls access of the applied pressure to the set volume. The filter assembly is operative to substantially reduce high frequency pressure ripples and allow static and quasi-static pressures to pass through to the sensing element, and may be manipulated to tune the pressure transducer assembly to achieve a desired dampening frequency. The filter assembly therefore enables one pressure transducer assembly outline to accurately measure pressure in various systems.

Abstract: The invention provides a micro-electro-mechanical device which includes a substrate, an electrode, and a diaphragm. The electrode includes plural vent holes. The diaphragm is disposed above and in parallel to the electrode, to form a capacitive sensor with the electrode. The diaphragm includes plural ribs protruding upward and/or downward from the diaphragm; the ribs are respectively disposed in correspondence to the plural vent holes and do not overlap nor contact the electrode. A method for making the micro-electro-mechanical device is also provided according to the present invention.

Abstract: Disclosed is detecting changes in pressure in a medium, with an optical fiber having a core diameter at an immersion surface contact of the fiber of less than 10 ?m; a layer of material deposited on said end of the fiber, the material being of a thickness of from about 2 nm to about 10 nm. Also disclosed is detecting pressure waves in a medium comprising: contacting the medium with a fiber optic, the fiber integrated with a light source and a detector, the fiber optic having a diameter of less than 10 ?m at an immersion surface contact of the fiber; providing a thin layer of material on the immersion surface contact, wherein said thin layer of material is of a thickness in a range of from about 2 nm to about 10 nm; and detecting Fresnel back reflections from the immersion end of the fiber.

Abstract: As may be consistent with one or more embodiments discussed herein, an integrated circuit apparatus includes a membrane suspended over a cavity, with the membrane and cavity defining a chamber. The membrane has a plurality of openings therein that pass gas into and out of the chamber. As the membrane is actuated, the volume of the chamber changes to generate a gas pressure inside the chamber that is different than a pressure outside the chamber. A sensor detects a frequency-based characteristic of the membrane responsive to the change in volume, and therein provides an indication of the gas pressure outside the chamber.

Abstract: A pressure transducer assembly that uses static pressure compensation to capture low-level dynamic pressures in high temperature environments. The pressure transducer assembly combines a static-dynamic pressure transducer with a micro-filter element to achieve a compact system that can be used in extreme temperature applications where low-level, dynamic pressure measurements are required in a high pressure environment.

Abstract: There is provided a pressure gauge for measuring the pressure of a gas. The pressure gauge comprises a housing connectable to the gas source and comprising an interior which is, in use, in communication with said gas. The pressure gauge further comprising a sensor assembly located within said housing and including a piezoelectric oscillator which, in use, is located in contact with said gas, said sensor assembly being arranged to measure the oscillation frequency of said piezoelectric oscillator in said gas and configured to determine, from the frequency measurement and the known temperature and known molecular weight of the gas, the pressure of the gas. By providing such an arrangement, an overpressure proof yet accurate pressure gauge can be provided. This is in contrast to conventional gauges which are damaged permanently by overpressure situations.

Abstract: A piezoelectric vacuum gauge includes an actuator with a flexible portion, an actuating unit, a sensor unit, a signal input terminal and a signal output terminal, and a fixture unit having a base portion and a cover portion. An external signal is generated by a signal generator. Receive and transmit an external signal to an actuating unit by the signal input terminal so that the actuating unit has a vibration. Prompt a flexible portion by the actuating unit to produce a first resonant motion when the actuating unit having the vibration. The first resonant motion converts into a second resonant motion because the flexible portion is subject to a damping force of ambient air. Prompt a sensor unit by the second resonant motion to cause a shape transformation of the sensor unit to generate a detecting signal. Output the detecting signal to an external instrument by a signal output terminal of sensor unit to calculate a vacuum pressure value.

Abstract: A pressure indicator for indicating pressure of a pressure source. The indicator comprises a first reservoir which defines a first enclosed volume having a first inlet pipe for communication between the first enclosed volume and a first source of pressurised fluid. A damping passage is provided in fluid communication with the first enclosed volume. A pressure oscillation damping means is provided in the damping passage. The damping means comprises a moveable body constrained within a limited range of motion along the damping passage.

Abstract: A remotely interrogatable pressure and/or temperature measuring device includes at least an acoustic wave sensor including at least one resonator coupled to a first antenna element, and an interrogation system including a second antenna element for transmission and reception. The device further includes an expandable tubular structure, the structure integrating a biocompatible material, and the acoustic wave sensor is encapsulated in the biocompatible material. The second antenna element operates at frequencies above several tens of MegaHertz.

Abstract: A vacuum sensor for sensing vacuum in a sealed enclosure is provided. The sealed enclosure includes active MEMS devices desired to be maintained in vacuum conditions. The vacuum sensor includes a motion beam anchored to an internal surface in the sealed enclosure. A driving electrode is disposed beneath the motion beam and a bias is supplied to cause the motion beam to deflect through electromotive force. A sensing electrode is also provided and detects capacitance between the sensing electrode disposed on the internal surface, and the motion beam. Capacitance changes as the gap between the motion beam and the sensing electrode changes. The amount of deflection is determined by the vacuum level in the sealed enclosure. The vacuum level in the sealed enclosure is thereby sensed by the sensing electrode.

Abstract: A pressure and temperature sensor comprising comprises at least a first resonator of the SAW type comprising a piezoelectric substrate, thinned at least locally, of the membrane type, a second resonator of the SAW type comprising a piezoelectric substrate and a third resonator of the SAW type comprising a piezoelectric substrate, characterized in that the first, the second and the third resonators are respectively on the surface of first, second and third individual piezoelectric substrates, each of the individual substrates being positioned on the surface of a common base section, locally machined away under said first resonator in such a manner as to liberate the substrate from said resonator so as to render it operational for the measurement of pressure. A method of fabrication for such a sensor is also provided.

Abstract: In one embodiment, a pressure sensor assembly for use with an application specific integrated circuit includes a capacitive sensor, a sensor coil within a first sensor compartment and operatively connected to the capacitive sensor to form a sensor L-C tank circuit, a measuring oscillator including a measuring coil located within a second sensor compartment and spaced apart from the sensor coil and a feedback circuit configured to provide a control signal for the measuring oscillator based upon an output of the measuring oscillator, and a low frequency signal source configured to provide a low frequency signal to the measuring oscillator.

Abstract: A pressure sensor includes a case, a vibrator, a detector, and a processor. The case includes a tubular section and a flat section. The tubular section has a hollow having an opening and is configured to be filled with a target fluid. The flat section closes the hollow. The flat section has a first surface facing the hollow, and a second surface opposite to the first surface. The vibrator is disposed on the second surface of the flat section of the case. The detector outputs a signal according to a vibration of the vibrator. The processor is operable to detect a frequency of the vibration of the vibrator based on the signal output from the detector, and to detect a pressure of the target fluid based on the detected frequency of the vibrator. This pressure sensor has a high sensitivity and excellent characteristics.

Abstract: A torsional sensor including a high-pressure sealing mechanism for sensing at least one parameter of a high-pressure fluid. The torsional sensor includes a torsional portion including a torsional rod sensor, a reference portion coupled to the torsional portion and including a transducer device and a high-pressure sealing mechanism coupled to the reference portion and the torsional portion and in sealing arrangement therewith. The high-pressure sealing mechanism is configured to provide for sealing therein the transducer device and allow for protrusion therethrough of a torsional rod sensor. At least a portion of the torsional sensor is mountable for immersion in the high-pressure fluid and operable to propagate a torsional wave that interacts with the high-pressure fluid along the at least portion of the torsional sensor so as to affect propagation of the torsional wave in a manner dependent on the at least one parameter of the high-pressure fluid.

Abstract: An improved manufacturing process for resonator-based pressure transducers is described. The process is a batch process in which several resonators are shaped simultaneously, using an etching process such as plasma etching. The end pieces are also shaped, if required, for several transducers. The end pieces and resonators are sandwiched together prior to separating the individual transducer units. The individual transducer units are then separated using a cutting process. The described process can be used to manufacture pressure transducers having a substantially smaller size, for example 5-6 mm outer dimensions and 2-3 mm resonators. The outer shape of the transducers can be a non-circular cylindrical shape such as that of a right square prism or an octagonal prism.

Abstract: A pressure sensor and method of sensing pressure is disclosed. An fluid port is coupled to a substrate. A first microchannel within the substrate is in fluid communication with the fluid port. The first microchannel includes a first compressible fluid, a first incompressible fluid and at least one first meniscus. A second microchannel within the substrate is in fluid communication with the fluid port. The second microchannel includes a second compressible fluid, a second incompressible fluid and at least one second meniscus. A pressure of the first meniscus and/or the second meniscus is determined.

Abstract: Disclosed herein is a MEMS component. The MEMS component according to the exemplary embodiment of the present invention includes: a plate-shaped membrane 110; a post 130 disposed under an edge 115 of the membrane 110; a stopper 140 disposed under the membrane 110 and disposed more inwardly than the post 130 so as to form a space 143 between the stopper 140 and the post 130; and a cap 150 disposed under the post 130 so as to cover the post 130, whereby the influence of disturbance or noise occurring from external environments or interference from surrounding sensors can be interrupted by using a predetermined region 145 of the membrane 110 disposed above the space 143.

Abstract: The innovations herein include a compact sensing device that is capable of measuring the conditions (e,g, pressure, temperature) inside a cylinder of an internal combustion engine. Aspects also include a cost-effective method of fabricating the sensing device. An exemplary sensing device includes a substrate, a beam, and piezo-resistive sensing elements. The beam, which is formed on the substrate, is capable of deflecting according to different pressures applied to different beam surfaces. The piezo-resistive sensing elements are coupled to the beam and detect beam deflection. The piezo-resistive sensing elements generate an electrical signal corresponding to the beam deflection.

Abstract: A process transmitter for measuring a process variable in an industrial process comprises a gauge pressure sensor, an excitation source and transmitter circuitry. The gauge pressure sensor measures a pressure difference between a process fluid and a reference volume, and generates a pressure sensor signal representing the pressure difference. The excitation source generates a pressure pulse within the reference volume to influence generation of the pressure sensor signal. The transmitter circuitry is connected to the gauge pressure sensor to provide an output related to a change in the pressure sensor signal due to the pressure pulse.

Abstract: A resonant pressure sensor including one or more resonant-type strain gauges arranged on a diaphragm may include a sensor substrate made of silicon and including one surface on which one or more resonant-type strain gauge elements are arranged and the other surface which is polished to have a thickness corresponding to the diaphragm, a base substrate made of silicon and including one surface directly bonded with the other surface of the sensor substrate, a concave portion formed in a portion of the base substrate bonding with the sensor substrate, substantially forming the diaphragm in the sensor substrate, and including a predetermined gap that does not restrict a movable range of the diaphragm due to foreign substances and suppresses vibration of the diaphragm excited by vibration of the resonant-type strain gauge elements, one or more conducting holes, and a fluid.

Abstract: A pressure detecting device includes: a resonator whose oscillation frequency varies depending on a pressure; a first oscillation circuit that oscillates the resonator and outputs a signal of a frequency corresponding to the pressure; an AT-cut quartz crystal resonator; a second oscillation circuit that oscillates the AT-cut quartz crystal resonator and outputs a reference clock signal; a measuring unit that measures the reference clock signal by the use of a reciprocal counting method; a temperature detecting unit that detects a temperature of the resonator; and a storage unit that stores coefficients of a first approximating polynomial for calculating a first correction value used to compensate for a frequency-temperature characteristic of the measuring unit, wherein the frequency-temperature characteristic of the value measured by the measuring unit includes a frequency-temperature characteristic of the AT-cut quartz crystal resonator and a frequency-temperature characteristic of the resonator.

Abstract: Measurement apparatus having a cantilever and a fluid flow channel, the cantilever being positioned in the channel so that it projects in a direction parallel to the direction of fluid flow. In an associated method, the cantilever is positioned in a fluid flow channel such that the cantilever extends parallel with the direction of fluid flow in the channel. Fluid is caused to flow in the channel at a known velocity. The resonant frequency of the cantilever is measured at one or more velocities of fluid flow and calculating the spring constant of the cantilever using the measured resonant frequency or frequencies. If the spring constant of the cantilever is known, the measurement of resonant frequency of the cantilever is used to determine the velocity of the fluid flow.

Abstract: A MEMS pressure sensor for sensing the pressure in a sealed cavity of a MEMS device, comprises a resonant MEMS device having a pressure sensor resonator element which comprises an array of openings. The resonant frequency of the resonant MEMS device is a function of the pressure in the cavity, with resonant frequency increasing with pressure. Over the pressure range 0 to 0.1 kPa, the average change in frequency is at least 10?6/Pa. The invention is based on the recognition that for fast oscillation, the elastic force causes the resonance frequency to shift. Therefore, it is possible to sense the pressure by a device with resonance frequency that is sensitive to the pressure.

Abstract: A condition measurement apparatus is provided and includes a gas turbine engine combustor having an end cover, a liner defining a liner interior and a fuel nozzle communicative with the liner interior, the end cover being formed to separate a cold side thereof, which is a relatively low temperature environment, from a hot side thereof, which is a relatively high temperature environment in which the liner and the fuel nozzle are disposed, the combustor being formed to define a fuel flow path extending through piping disposed at the cold side of the end cover by which fuel is deliverable to the fuel nozzle, and a condition sensing device operably mounted on the piping.

Abstract: An altitude sensor includes a support frame and a sensor unit mounted in the support frame. The support frame has an upper shield and a lower shield. The sensor unit includes a beam and a damper. The damper is configured to move up and down in response to the air flow, which drives the beam to move up and down accordingly. Distances from the damper to the upper shield and the lower shield are less than those from the beam to upper shield and the lower shield. The altitude sensor possesses super specific properties such as unlimited sensitivity to flying height because of no size constraints and unchanged sensitivity under a changing environment, a selfprotective mechanism to resist deformation in case of an accident, easy manufacture process as well as low production cost. The present invention also discloses an altitude sensor for use in a disk drive device and a disk drive device with the altitude sensor.

Abstract: A pressure sensor includes an outer body defining a sensor cavity and a resonator element located at least partially within the sensor cavity. The pressure sensor also includes a bellows having an outer side and an inner side and that is located at least partially within the outer body. the inner side of the bellows defines an internal volume and is configured to receive a measured fluid into the internal volume. The pressure sensor also includes a measuring fluid filling at least a portion of an area between the outer side and the outer body.

Abstract: The invention relates to a sensor element for pressure measurement, having a substrate (5) and at least one mass element (1), which is arranged spaced apart from the substrate (5) and is connected in an oscillating manner to the substrate (5) and/or a support body (6) fixed relative to the substrate (5), so that a gap is formed between the mass element (1) and the substrate (5), the width of which can be varied through oscillations of the mass element (1). At least one recess and/or at least one bushing (4) is located in the surface of the substrate (5) delimiting the gap, which recess is used for reducing the damping of the oscillation of the mass element through the gas or plasma surrounding the mass element (1). The sensor element is used in particular in pressure sensors for measuring pressures in the vacuum range. Through the use of the sensor element according to the invention as a pressure sensor, maximum pressures up to the range of atmospheric air pressure can be recorded.

Abstract: A pressure transducer comprising a housing and a piezoelectric resonator in the housing, wherein the resonator is made of a piezoelectric crystal having Curie temperature greater than 1000° C. or having no Curie temperature up to its melting point greater than 1000° C., and the piezoelectric crystal has a piezoelectric constant more than two times greater than that of quartz.

Abstract: A pressure transducer assembly that uses static pressure compensation to capture low-level dynamic pressures in high temperature environments. The pressure transducer assembly combines a static-dynamic pressure transducer with a micro-filter element to achieve a compact system that can be used in extreme temperature applications where low-level, dynamic pressure measurements are required in a high pressure environment.

Abstract: A system for the detection of contaminates of a fluid in a conduit. The conduit is part of a fluid distribution system. A chemical or biological sensor array is connected to the conduit. The sensor array produces an acoustic signal burst in the fluid upon detection of contaminates in the fluid. A supervisory control system connected to the fluid and operatively connected to the fluid distribution system signals the fluid distribution system upon detection of contaminates in the fluid.

Abstract: In one embodiment, a pressure sensor assembly for use with an application specific integrated circuit includes a capacitive sensor, a sensor coil within a first sensor compartment and operatively connected to the capacitive sensor to form a sensor L-C tank circuit, a measuring oscillator including a measuring coil located within a second sensor compartment and spaced apart from the sensor coil and a feedback circuit configured to provide a control signal for the measuring oscillator based upon an output of the measuring oscillator, and a low frequency signal source configured to provide a low frequency signal to the measuring oscillator.

Abstract: A pressure transducer assembly for measuring pressures in high temperature environments employing an elongated tube which is terminated at one end by an acoustic micro-filter. The micro-filter is operative to absorb acoustic waves impinging on it with limited or no reflection. To improve the absorption of acoustic waves, the elongated tube may be tapered and/or mounted to a support block and further convoluted to reduce the overall size and mass of the device. A pressure transducer with a diaphragm flush may be mounted to the elongated tube and extend through to the inner wall of the tube. Hot gases propagate through the elongated tube and their corresponding pressures are measured by the transducer. The acoustic filter operates to absorb acoustic waves resultant from the hot gases, therefore enabling the pressure transducer to be mainly responsive to high frequency waves associated with the gas turbine operation.

Abstract: An atmospheric pressure measuring apparatus allows a transmitter to transmit an acoustic wave for measurement of the atmospheric pressure. Air propagates the acoustic wave. A receiver receives the acoustic wave. Since the intensity of the acoustic wave changes to follow the variation of the atmospheric pressure, the atmospheric pressure can be measured based on the intensity of the acoustic wave received at the receiver. The atmospheric pressure is in this manner measured with such a simplified structure.

Abstract: An improved manufacturing process for resonator-based pressure transducers is described. The process is a batch process in which several resonators are shaped simultaneously, using an etching process such as plasma etching. The end pieces are also shaped, if required, for several transducers. The end pieces and resonators are sandwiched together prior to separating the individual transducer units. The individual transducer units are then separated using a cutting process. The described process can be used to manufacture pressure transducers having a substantially smaller size, for example 5-6 mm outer dimensions and 2-3 mm resonators. The outer shape of the transducers can be a non-circular cylindrical shape such as that of a right square prism or an octagonal prism.

Abstract: The invention provides a vibrating cylinder transducer for measuring the pressure or density of a fluid medium comprising: a cylindrical vibrator, in use having at least one surface coupled to a fluid medium to be measured; a drive means for vibrating the cylindrical vibrator; a sensor for detecting the resonant frequency of the cylindrical vibrator; and an output coupled to the sensor, the output configured to provide an output signal indicative of the pressure and/or the density of the fluid medium; wherein the surface coupled to the fluid medium is coated in a corrosion resistant polymer layer. Preferably the corrosion resistant polymer layer is formed from parylene.

Abstract: A pressure detecting device includes: a resonator whose oscillation frequency varies depending on a pressure; a first oscillation circuit that oscillates the resonator and outputs a signal of a frequency corresponding to the pressure; an AT-cut quartz crystal resonator; a second oscillation circuit that oscillates the AT-cut quartz crystal resonator and outputs a reference clock signal; a measuring unit that measures the reference clock signal by the use of a reciprocal counting method; a temperature detecting unit that detects a temperature of the resonator; and a storage unit that stores coefficients of a first approximating polynomial for calculating a first correction value used to compensate for a frequency-temperature characteristic of the measuring unit, wherein the frequency-temperature characteristic of the value measured by the measuring unit includes a frequency-temperature characteristic of the AT-cut quartz crystal resonator and a frequency-temperature characteristic of the resonator.

Abstract: A relative pressure sensor for registering pressure of a medium relative to surrounding atmospheric pressure includes: a pressure measuring cell having a measuring membrane and a platform, wherein pressure of the medium can act on a first side of the measuring membrane facing away from the platform, and wherein the platform has a reference air opening, through which surrounding atmospheric pressure can act on a second side of the measuring membrane facing the platform. A support body, through which a reference air duct extends between a first surface section and a second surface section of the support body is provided, wherein the pressure measuring cell is affixed to the support body with a pressure resistant, bonded adhesive.

Abstract: A receiver receives an acoustic wave in an atmospheric pressure measuring apparatus. Since a variation in the intensity of an acoustic wave reflects a variation in the atmospheric pressure, the atmospheric pressure can be measured based on the intensity of the acoustic wave received at the receiver. The atmospheric pressure can in this manner easily be measured with a simplified structure.

Abstract: A sensor chip has a substrate and a comb-teeth electrode arranged on the substrate. The sensor chip is fixed to a diaphragm structure to be distorted by receiving pressure, and is fixed to the diaphragm structure only through a predetermined fix area so as to detect the pressure. The fix area is defined on only a part of the sensor chip opposing to the diaphragm structure. The sensor chip is restrained by the diaphragm structure in a direction of transmitting surface acoustic wave. Flexibility of the sensor chip in a perpendicular direction approximately perpendicular to the wave transmitting direction is larger than that in the transmitting direction.

Abstract: A MEMS pressure sensor for sensing the pressure in a sealed cavity of a MEMS device, comprises a resonant MEMS device having a pressure sensor resonator element which comprises an array of openings. The resonant frequency of the resonant MEMS device is a function of the pressure in the cavity, with resonant frequency increasing with pressure. Over the pressure range 0 to 0.1 kPa, the average change in frequency is at least 10?6/Pa. The invention is based on the recognition that for fast oscillation, the elastic force causes the resonance frequency to shift. Therefore, it is possible to sense the pressure by a device with resonance frequency that is sensitive to the pressure.

Abstract: A remotely interrogatable pressure and/or temperature measuring device includes at least an acoustic wave sensor including at least one resonator coupled to a first antenna element, and an interrogation system including a second antenna element for transmission and reception. The device further includes an expandable tubular structure, the structure integrating a biocompatible material, and the acoustic wave sensor is encapsulated in the biocompatible material. The second antenna element operates at frequencies above several tens of MegaHertz.

Abstract: An accelerometer includes a pressure transducer; and a vibration-to-pressure converter (VPC). The VPC may include a housing mechanically coupled to an object to be measured, and a diaphragm sealing the housing to form a chamber, the chamber being fluidly coupled to the pressure transducer. A power generator and motor including the accelerometer are also presented.

Abstract: The invention relates to a sensor (1) and a method for measuring pressure, variation in sound pressure, a magnetic field, acceleration, vibration, or the composition of a gas. The sensor (1) comprises an ultrasound transmitter (2), and a cavity (4) arranged in connection with it. According to the invention, the sensor (1) comprises a passive sensor element (3, 3?) located at the opposite end of the cavity (4) to the ultrasound transmitter (2), the distance of which from the ultrasound transmitter (2) is selected in such a way that the resonance condition is met at the ultrasound frequency used, the ultrasound transmitter (2) comprises a light-construction diaphragm oscillator (9), which is thus well connected to the surrounding medium, and the sensor includes means for measuring the interaction between the ultrasound transmitter (2) and the cavity (4).

Abstract: A pressure transducer comprising a housing and a piezoelectric resonator in the housing, wherein the resonator is made of a piezoelectric crystal having Curie temperature greater than 1000° C. or having no Curie temperature up to its melting point greater than 1000° C., and the piezoelectric crystal has a piezoelectric constant more than two times greater than that of quartz.

Abstract: A method of manufacturing a pressure monitoring package comprises the steps of mounting a plurality of resonators onto a substrate 1, mounting the substrate 1 in a package base 11, mechanically constraining the package base 11 within a mechanical preloading jig, and adjusting the preload using the jig whilst measuring the frequency of the SAWs until the required frequency is obtained. A lid 7 is then welded onto the package base 11 using a laser welder, after which the preload frequency of the package 10 is fine tuned by using the laser welder to produce laser marks 21-28, 31-38 on the outside of the package 10.

Abstract: The invention relates to a device and a method for detecting a fault in a measurement device comprising a resonator and means for measuring a resonant frequency of the resonator. According to the invention, the device further includes means delivering information (S3) representative of the quality factor of the resonator (3) at the resonant frequency.

Abstract: The invention relates to a pressure determination device for determining the pressure in a fuel storage arrangement, with a connection element for connecting the pressure determination device to the fuel storage arrangement, a first chamber, a connecting line for communicating connection of the interior of the connection element to the first chamber, a second chamber, a membrane, and a switch, the interior of the connection element, the connecting line and the first chamber being made to accommodate throughflow of a fluid, the first chamber being made separated fluid-tight from the second chamber at least by means of the membrane, and the membrane being made for actuating the switch at least depending on the pressure of the fluid in the first chamber, and the connecting line being provided with a vibration damping element through which a fluid can flow.

Abstract: A pressure detection unit includes: a first piezoelectric resonator element having a vibrating portion and a pair of base portions connected to both ends of the vibrating portion; a second piezoelectric resonator element having a resonating arm and a base portion integrated with one end of the resonating arm; a diaphragm having a pair of supporting portions to which the base portions of the first piezoelectric resonator element are bonded; and a base disposed to be opposed to the diaphragm. In the pressure detection unit, the base portion of the second piezoelectric resonator element is joined to one of the base portions of the first piezoelectric resonator element in an identical plane.

Abstract: A sensor chip has a substrate and a comb-teeth electrode arranged on the substrate. The sensor chip is fixed to a diaphragm structure to be distorted by receiving pressure, and is fixed to the diaphragm structure only through a predetermined fix area so as to detect the pressure. The fix area is defined on only a part of the sensor chip opposing to the diaphragm structure. The sensor chip is restrained by the diaphragm structure in a direction of transmitting surface acoustic wave. Flexibility of the sensor chip in a perpendicular direction approximately perpendicular to the wave transmitting direction is larger than that in the transmitting direction.