Abstract: There is provided a highly accurate electrical capacitance diaphragm pressure sensor capable of reducing temperature drift that arises when a pressure-travel coefficient changes with temperature variations of a fluid whose pressure is sensed.

Abstract: A device for sensing pressure using two perforated rigid films in which a diaphragm is mounted between the first two films. The device senses positive and negative pressure through a port or opening to the region for which pressure data is desired. The device communicates capacitive pressure and changes in that pressure. The flexible diaphragm is spaced from the first and second films such that the flexible diaphragm is adapted to flex toward the first film when pressure increases in the opening and is adapted to flex toward the second film when pressure decreases in the opening to change the capacitance between the diaphragm and at least one of the first and second films. Spacers are used to position all three elements.

Abstract: A device for sensing pressure including a chamber defining part having a first diaphragm mounted in communication with the sealed chamber defining part, and a second diaphragm electrically insulated from the first, preferably by a spacer. The diaphragms are flexible and have a conductive surface. A sensor chamber is mounted on the other side of the second diaphragm. It has an opening in communication with a sensing atmosphere. One of the diaphragms includes openings it its surface to permit fluid to flow through the openings and the other diaphragm is solid and responds to change in pressure in the sensor chamber to move away from or toward the one diaphragm. Electrical connections measure the capacitance between the diaphragms as a function of the pressure in the sensor chamber.

Abstract: A detector providing an electrical signal in response to the pressures encountered in sensing breath inhalation in respirators. The detector uses a capacitive pressure sensor formed by a flexible conductive diaphragm separated from fixed electrodes by a layer of dielectric film. Deflection of the diaphragm by pressure introduces a low permittivity space in the sensor resulting in a substantial change in capacitance. The change in capacitance modifies the frequency of an oscillator. A frequency responsive circuit provides balancing electrostatic force feedback voltage to the diaphragm. The force feedback stiffens the diaphragm and maintains it in a high capacitance, high sensitivity state. This feedback reduces sensitivity to changes in the diaphragm mechanical properties. Signal filtering reduces the effects of long term drift and environmental factors.

Abstract: A capacitive-type pressure sensor comprising a glass plate having an electrode formed thereon. A diaphragm is formed from a semiconductor material and bonded to the glass substrate to define an enclosed cavity containing at least a portion of the electrode, to thereby define a capacitive element, through which, in use, an electrical signal may be passed to determine a capacitance thereof which is indicative of the pressure to be determined.

Abstract: A measurement system includes multiple analog sensor elements and multiple sigma-delta modulators for producing digital outputs. Each sigma-delta modulator receives charge packets from one or more sensor element and charge packets from a shared element (which may be a sensor or a reference element). The sigma-delta modulators are operated synchronously in separate phases, so that the shared element either delivers or does not deliver a charge packet of the sign desired by a sigma-delta modulator only during the phase associated with that sigma-delta modulator.

Abstract: A method of determining the accuracy of a pressure sensor in a surgical cassette is disclosed. The method involves displacing a diaphragm of the sensor a pre-defined amount of displacement, and measuring the force exerted on the diaphragm by the displacing step. The accuracy of the pressure sensor is determined by comparing the force measured in the measuring step to a pre-defined force for the pre-defined amount of displacement.

Abstract: A method of manufacturing strain-detecting devices is provided. First, plural cylindrical substrates, each of which has one end closed by a diaphragm, are fixedly placed at predetermined positions of a fixing plate. A positioning marker is previously given to the fixing plate. The fixing plate having the substrates is then assembled into a jig. The jig sustains the substrates so that an outer surface of the diaphragm of each substrate is held at the same level. Through positioning the substrates, all the diaphragms are then positioned in place in a plane direction of the fixing plate with reference to the positioning marker. A strain gage portion is simultaneously formed on each of all the diaphragms. The fixing plate is then disassembled from the jig. In this step, the substrates with the strain gage portions, i.e., strain-detecting devices, are separated from the fixing plate.

Abstract: It is an object of the present invention to provide a touch mode capacitive pressure sensor having higher pressure durability than conventional sensors. In this invention, a touch mode capacitive pressure sensor has a diaphragm made from boron-doped silicon, and the boron concentration at the top face of the diaphragm is equal to or greater than 1×1019 cm?3 and less than 9×1019 cm?3. Further, in this invention, a touch mode capacitive pressure sensor has a conductive diaphragm made by doping of an impurity and anisotropic etching, and the etch pit density on the top face of the diaphragm is equal to or less than five per ?m2, and preferably equal to or less than one per ?m2. As a result, the pressure durability of the diaphragm is greatly improved.

Abstract: A capacitive pressure transmitter is provided. In one aspect, the transmitter includes a capacitive pressure sensor coupled directly to the measured media without any intervening fluid isolation. A filter is preferably used to keep particulates from reaching the measuring diaphragm. In another aspect, a capacitive pressure transmitter is provided with at least one self-contained isolator interposed between a process connection and the capacitive pressure sensor. In both aspects, the capacitive pressure transmitter is relatively small and preferably constructed from materials that facilitate low-cost manufacture.

Abstract: A variable capacitance measuring device can comprise a glass-ceramic insulator having a coefficient of thermal expansion that closely matches the coefficient of thermal expansion of a metallic materials used within the device. The glass-ceramic material may chemically bond to the surfaces of the metallic materials to provide a hermetic seal and eliminate the need for a separate glass seal or grooves within the electrode assembly. Additionally, a single-piece electrode assembly can be used instead of a separate electrode assembly (for the electrical feedthrough) and electrode. A shim may be used during the formation of the insulating material to reduce the likelihood of the insulator adhering to surfaces of the electrode portion during the manufacturing process. Also, separate bake-out and getter activation cycles may be combined into a single heat cycle.

Abstract: A capacitance diaphragm gauge (CDG) for measuring pressure includes a flush diaphragm mounted to a body structure via a shim or other raised perimeter portion. The diaphragm and the shim are welded to the body structure while the diaphragm is maintained at an elevated temperature. Contraction of the diaphragm as it cools pretensions the diaphragm to substantially reduce hysteresis effects. An electrode advantageously includes two portions with one portion providing excellent bonding characteristics and the other portion having temperature characteristics corresponding to the body structure and the diaphragm. An alternative CDG includes two identical electrodes with a first electrode positioned proximate to the center of the diaphragm and with a second electrode positioned proximate to the perimeter of the diaphragm. The second electrode provides a second capacitance signal that is used to compensate for changes in capacitance between the diaphragm and the first electrode caused by temperature changes.

Abstract: An electronic detector configuration enables the accurate determination of pressure differences in scenarios in which conventional detectors and detector systems introduce inherent thermal inequalities at the interface with their immediate environs. A preferred embodiment of the present invention accurately measures snow water equivalent (SWE) while eliminating the need for fluid-filled pillows that contain environmentally hazardous fluids. By matching the thermal conductivity of)surrounding soil to a detector configuration having an inherently low specific heat, it minimizes effects of differences in thermal conductivity at the snow/soil interface that cause SWE pressure sensor measurement errors. Further, it minimizes thermal effects by keeping soil moisture under the configuration approximately the same as that of surrounding soil.

Abstract: A microfluidic device and method for capacitive sensing. The device includes a fluid channel including an inlet at a first end and an outlet at a second end, a cavity region coupled to the fluid channel, and a polymer based membrane coupled between the fluid channel and the cavity region. Additionally, the device includes a first capacitor electrode coupled to the membrane, a second capacitor electrode coupled to the cavity region and physically separated from the first capacitor electrode by at least the cavity region, and an electrical power source coupled between the first capacitor electrode and the second capacitor electrode and causing an electric field at least within the cavity region. The polymer based membrane includes a polymer.

Abstract: A method for manufacturing a micromechanical pressure sensor and a pressure sensor manufactured using this method. The pressure is measured in the pressure sensor composed of at least two components via a capacitance measurement of a capacitor, the pressure sensor having at least one first electrode and one first diaphragm. The movement of the diaphragm causes a change in the capacitance of the capacitor which may be used in the capacitance measurement as a measure for the pressure variable to be measured. It is important that, prior to assembly, the first and the second components of the pressure sensor be processed separately. The first component has at least one semiconductor material and the first electrode, whereas the second component is made of metal, at least in part, and contains at least the first diaphragm.

Abstract: A high sensitivity pressure sensor with long term stability including a housing with first and second chambers, a membrane separating the first and second chambers, a first electrode located in the first chamber and spaced from one side of the membrane forming a first capacitor therewith, and a second electrode located in the second chamber and spaced from an opposite side of the membrane forming a second capacitor therewith. A measuring circuit is connected across the first and second capacitors for measuring membrane displacement by detecting differences in capacitance between the first and second capacitors and a compensation circuit is configured to apply an electric field to the membrane as a compensating force by reducing the voltage difference between the first electrode and the membrane and simultaneously increasing the voltage difference between the second electrode and the membrane or vice versa to provide long term stability.

Abstract: A capacitive vacuum sensor includes an elastic diaphragm electrode and a rigid fixed electrode opposite the elastic diaphragm electrode. An internal space is defined between the elastic diaphragm electrode and the rigid fixed electrode. The elastic diaphragm electrode deflects elastically in response to any change in the pressure of a gas applied on the elastic diaphragm electrode, and the capacitive vacuum sensor is responsive to any change in the capacitance between the elastic diaphragm electrode and the rigid fixed electrode that may occur in accordance with the deflection of the elastic diaphragm electrode so that it can measure the pressure of the gas. The vacuum sensor can include an anticorrosive diaphragm electrode that can resist the corrosive action of the reactive gas when it is exposed to such gas, and can be fabricated by the micromachining technology.

Abstract: A diaphragm-type semiconductor device includes a semiconductor substrate, a surface of which is substantially flat, a diaphragm, which covers a circular pressure reference space located on the surface, and a circular electrode layer, a middle part of which is embedded in the diaphragm. The electrode layer is larger than the space and is coaxial with the space. Therefore, internal stress is balanced between inner and outer sides of the diaphragm, and a step formed at the outer edge of the top electrode layer is separated from the diaphragm. The device also includes a step adjuster around the space on the surface. Therefore, another step formed at the outer edge of the space disappears, and a new step is formed separately from the diaphragm at the outer edge of the step adjuster. With this structure, the diaphragm has a desired flatness.

Abstract: A capacitance diaphragm gauge (CDG) for measuring pressure includes a flush diaphragm mounted to a body structure via a shim or other raised perimeter portion. The diaphragm and the shim are welded to the body structure while the diaphragm is maintained at an elevated temperature. Contraction of the diaphragm as it cools pretensions the diaphragm to substantially reduce hysteresis effects. An electrode advantageously includes two portions with one portion providing excellent bonding characteristics and the other portion having temperature characteristics corresponding to the body structure and the diaphragm. An alternative CDG includes two identical electrodes with a first electrode positioned proximate to the center of the diaphragm and with a second electrode positioned proximate to the perimeter of the diaphragm. The second electrode provides a second capacitance signal that is used to compensate for changes in capacitance between the diaphragm and the first electrode caused by temperature changes.

Abstract: A capacitive pressure sensor and its manufacturing method can simplify the alignment and the bonding process in a vacuum, and stably carry out the bonding process. The capacitive pressure sensor includes an insulating, first substrate with a capacitance electrode, a second substrate which has a diaphragm electrode so as to separate a vacuum chamber and a pressure-measuring chamber on respective surfaces, and an insulating, third substrate with a gas inlet. The substrates are bonded in a manner that the capacitance electrode faces the diaphragm electrode and the pressure-measuring chamber leads to the gas inlet. In addition, a getter chamber is formed in the same surface of the second substrate as the pressure-measuring chamber, and the getter chamber is connected to the vacuum chamber.

Abstract: A capacitive pressure sensor for measuring a pressure applied to an elastic member includes a capacitive plate disposed adjacent to the elastic member so as to define a gap between a planar conductive surface of the elastic member and a corresponding planar surface of the capacitive plate. The gap, capacitive plate and elastic member together define a capacitor having a characteristic capacitance. The sensor further includes an elongated electrical conductor characterized by an associated inductance value. The conductor is fixedly attached to and electrically coupled with the capacitive plate. The gap between the capacitive plate and the elastic member varies as a predetermined function of the pressure applied to the elastic member so as to vary the characteristic capacitance. The capacitor and the electrical conductor together form an electrical resonator having a characteristic resonant frequency. Varying the capacitance of this tank circuit varies the resonant frequency of the tank circuit.

Abstract: A capacitive pressure sensor comprises a pair of conductive plates surrounding a compressible dielectric to form a capacitor. Changes in pressure create changes in the capacitance of the capacitor which in turn may be measured to determine the changes in pressure. The pressure sensor may be constructed to be temperature and centripetal force compensated so that it may be positioned in a tire. A further embodiment uses the conductive plates to form a radiating element for the sensor such that it may wirelessly communicate with a remote interrogator.

Abstract: A pressure-measuring device with monitoring for diaphragm fracture comprises a housing with a passage whose two openings at the end faces of the housing are closed by a first deformation body and a second deformation body. The passage is completely filled with a transmission liquid in order to transmit the process pressure from the first deformation body to the second deformation body. The device has components for monitoring a material property of the transmission liquid. A change in the material property indicates contamination by the process medium and thus a fracture of the first deformation body. The material property monitored is preferably the relative dielectric constant.

Abstract: A heater is disclosed for use with pressure transducers. The disclosed heater includes a first heating element and a second heating element. The first heating element is characterized by a first electrical resistance. The second heating element is characterized by a second electrical resistance. In preferred embodiments, the first electrical resistance is different than the second electrical resistance. The disclosed heater can be used to accurately heat a pressure transducer to at least four different operating temperatures by selectively (a) connecting the first heating element to the transducer temperature control circuitry, (b) connecting the second heating element to the transducer temperature control circuitry, (c) connecting the first and second heating elements in series with the transducer temperature control circuitry, or (d) connecting the first and second heating elements in parallel with the transducer temperature control circuitry.

Abstract: The active brazing solder for brazing ceramic parts of alumina, particularly of high-purity alumina, contains a maximum of 12 wt. % Ti, a maximum of 8 wt. % Be, and less than 16.5 wt. % Fe, the remainder being Zr and any impurities that may be present. The active brazing solder has the following behaviour/features: Brazing temperature: lower than 1,000° C.; the brazed joint is high-vacuum-tight over a long period of time; the coefficient of thermal expansion of the active brazing alloy is substantially identical to that of the alumina ceramic in the entire temperature range covered during the brazing process; the strength of the brazed joint between the two ceramic parts is so high that under tensile loading, fracture will result not at the joint, but in the adjacent ceramic; the pressure resistance of the active brazing solder is greater than 2 GPa; the active brazing solder is very good processable into powders having particle sizes on the order of 10 &mgr;m.

Abstract: An arrangement for measuring the true position of a diaphragm within a diaphragm valve assembly utilizes a thin conductive element disposed in the valve between the diaphragm membrane and the actuator. The conductive element and the valve body are then used as the plates of a parallel plate capacitor, where the measured capacitance will vary as a function of the position of the diaphragm mambrane, having a first value when the diaphragm is in the “open” position and a second value when the diaphragm is in the “closed” position. Position values between the “open” and “closed” positions can also be determined, as well as the presence of different fluids within the valve body when the valve is in the “open” position.

Abstract: A pressure transducer designed to transform static pressure or dynamic pressure applied to a diaphragm into a corresponding electrical signal and a method of manufacturing the same are provided. The transducer includes a fixed electrode formed in an upper surface of a substrate and a moving electrode provided in the diaphragm disposed above the fixed electrode through a cavity. The substrate has formed in the bottom thereof at least one hole which is used in a manufacturing process for removing a sacrificial layer formed between the diaphragm and the upper surface of the substrate in dry etching to form the cavity.

Abstract: A port fitting (102) is formed with a closed, pedestal end forming a diaphragm (102a) on which a strain gauge sensor is mounted. A support member (106) is received on the pedestal end and is formed with a flat end wall (106a) having an aperture (106d) aligned with the sensor. A circuit assembly (108) is bonded to the flat end wall and the sensor wire bonded to the electronic circuit. A cover member (114) placed on the support member, is provided with a cavity for a metal shield member (118) fitted inside the cover member before assembly. The shield member is formed with spring members (118b) extending outside the perimeter of the cover member. The cover member is formed with circular cavities (114d) extending in an axial direction to provide seating for contact spring members (117), making electronic contact to the sensor electronics and protruding beyond the body of the cover member. The cover member is also fitted with a circular elastomer gasket member (116), providing an environmental seal.

Abstract: A method of manufacturing a pressure sensor house assembly which contains a reference cavity, in which a vacuum exists, and a getter capable of being thermally activated. The getter is activated by directly contacting the getter with an exterior heated body, conducting heat from the exterior heated body, maintaining the exterior heated body in direct contact with the getter for a predetermined period of time, and removing the exterior heated body.

Abstract: A method for manufacturing a sensor component, in particular, a thin-film high-pressure sensor, as well as a sensor component, is described, in which at least one measuring element, in particular an expansion measuring strip is arranged on a membrane, and separated from the membrane through an electrically insulating film, the measuring element being arranged on an electrically insulating substrate, which is mounted in a subsequent step onto the membrane on the side that faces away from the measuring element, so that the electrically insulating substrate forms the electrically insulating film. The electrically insulating substrate performs both a carrier function during the application of the expansion measuring strip to the substrate as well as an insulation function after the mounting of the substrate onto the membrane. In this way, the application of a separate insulation film made of silicon dioxide becomes unnecessary.

Abstract: A micromechanical differential pressure sensor device for measuring a pressure difference between two mutually separated spaces or media, in which two absolute pressure measuring devices are monolithically integrated on a single support substrate, in particular on a semiconductor chip. The absolute pressure measuring devices are preferably fabricated by surface micromachining.

Abstract: A capacitive sensor includes an elastic member extending about a central axis, having a central region, a peripheral region, a first side, and a second side. An overpressure stop member has an inner surface and an outer surface. The inner surface of the overpressure stop member has a contour adapted to limit deflection of the elastic member caused by a differential pressure between the two regions across the elastic member. The outer surface of the overpressure stop member has an first electrically conductive region. A second plate is spaced apart from the outer surface of the overpressure stop member, and being connected to the central region of the elastic member by a post, wherein the post transfers deformation of the elastic member caused by differential pressure across the elastic member to movement of the second plate along the central axis.

Abstract: A position sensor comprises a substrate having an array of pressure sensors and a membrane overlying the substrate. The membrane includes physical parameters which vary with position. The membrane may include discontinuous regions and protrusions which affect the way in which forces on the membrane are distributed to the substrate. A pressure sensor may also include a controller for receiving pressure information from the substrate, with a signal processor being programmed to localize the depressed region or regions of the substrate.

Abstract: The present invention discloses a relaxor material lead iron tungstate which has been synthesized in doped and undoped conditions by single and two step heat treatment. The relaxor material is seen to exhibit almost negligible hysteresis and a transducer made thereby shows pressure measurement capability over a wide range from 0.5 MPa to 415 MPa with accuracy of ±0.05%.

Abstract: A pressure sensor may include a first membrane that flexes in response to pressure, a reference cavity covered by the first membrane where the reference cavity contains a vacuum and a second membrane, adjacent to the first membrane, the first and second membranes forming a capacitor having a capacitance that varies in accordance with the flexing of the first membrane and the pressure.

Abstract: A capacitive pressure sensor includes a first substrate (1), a first flat electrode (1a) formed on the first substrate (1), a pressure-sensing frame (4) surrounding the first flat electrode (1a) provided on the first substrate (1), second substrates (2, 3) connected to the pressure-sensing frame (4) opposedly to the first substrate (1) and forming a capacitance chamber (7) together with the first substrate (1) and the pressure-sensing frame (4), a stage (5) provided on the second substrates (2, 3) in the capacitance chamber (7), separated from the pressure-sensing frame (4), and opposed to and separated from the first flat electrode (1a), and a second flat electrode (2a) provided on the stage (5) and opposed to the first flat electrode (1a), wherein the pressure-sensing frame (4) deforms elastically according to a pressure applied to the first and second substrates (1, 2, 3).

Abstract: A capacitive pressure sensor for measuring a pressure applied to an elastic member includes a capacitive plate disposed adjacent to the elastic member so as to define a gap between a planar conductive surface of the elastic member and a corresponding planar surface of the capacitive plate. The gap, capacitive plate and elastic member together define a capacitor having a characteristic capacitance. The sensor further includes an elongated electrical conductor characterized by an associated inductance value. The conductor is fixedly attached to and electrically coupled with the capacitive plate. The gap between the capacitive plate and the elastic member varies as a predetermined function of the pressure applied to the elastic member so as to vary the characteristic capacitance. The capacitor and the electrical conductor together form an electrical resonator having a characteristic resonant frequency. Varying the capacitance of this tank circuit varies the resonant frequency of the tank circuit.

Abstract: The invention concerns a pressure sensor (1), able to operate at high temperature and measure the pressure of a hostile medium, comprising: a sensing element (4) integrating a membrane (8) in monocrystalline silicon carbide, made by micro-machining a substrate in polycrystalline silicon carbide, a first surface of membrane (8) intended to contact said medium, a second surface of membrane (8) comprising membrane deformation detection means (9) connected to electric contacts (10) to connect electric connection means (11), the surfaces of sensing element (4) contacting said medium being chemically inert to this medium; a carrier (5) to support sensing element (4) so that said first surface of membrane (8) may be contacted with said medium and the second surface of membrane (8) may be shielded from said medium, carrier (5) being in polycrystalline silicon carbide; a seal strip (6), in material containing silicon carbide, brazed between carrier (5) and sensing element (4) to protect the second surface of membra

Abstract: The present publication discloses a capacitive pressure sensor structure, in particular for measurement of absolute pressure, and a method for manufacturing the sensor. The sensor comprises at least one fixed electrode (3), and at least one movable electrode (6, 7) electrically isolated from said fixed electrode (3) and spaced apart (10) from said fixed electrode (3). According to the invention, a portion of said movable electrode (6, 7) is formed from a porous polycrystalline silicon layer (6) that in a finished component remains as an integral portion of said flexibly movable electrode (6, 7).

Abstract: A capacitor industrial process control transmitter includes a three-phase excitation circuit to charge a sensing capacitor and a compensation capacitor of the transmitter and transfer charges to an integrator. The sensing capacitor is charged during the first phase. During the second phase, the voltage to the sensing capacitor is reversed, and the charge on the sensing capacitor is pumped to the integrator. Also, the compensation capacitor is charged with the reversed voltage during the second phase. During the third phase, the voltage to the compensation capacitor is changed, and the charge on the compensation capacitor is pumped to the integrator.

Abstract: A displacement responsive device e.g. a measurement probe (110) is disclosed. Displacement of a stylus (130) causes resilient movement of a carriage (134) supported by planar springs (112) and (114). This movement is detected by a capacitance sensor (160), formed from two cylinders (164) and (166). The cylinders move in at least three degrees of freedom and changes in their capacitance during the said movement can be determined by a circuit (e.g. FIG. 5). Movement in x, y and z directions can be sensed.

Abstract: A force or pressure sensor structure has a membrane and a counter-structure, both being provided with electrodes for determining capacitors. There are at least two capacitors connected in series or in parallel for determining a desired pressure/capacitance dependence or a desired force/capacitance dependence. The counter-structure preferably is fixed and has a multiplicity of electrode areas in the shape of segments of a circle in order to assemble electrode areas obtained by optimization in a series or parallel connection. The interconnection of the individual elementary capacitors are preferably realized by a multilayer construction. The same membrane and an identical evaluation circuit can be used for any pressure/capacitance or force/capacitance dependence desired, with only the multilayer construction requiring modification for a different dependence. The electrode structures can preferably be defined by a few specifications, such as e.g., length, width, spacing or angle, radius, respectively.

Abstract: A process transmitter for measuring a process pressure includes a pressure sensor in a sensor housing. An isolation diaphragm which isolates fill fluid from process fluid is spaced apart from a process fluid seal. The spacing reduces deformation of the isolation diaphragm due to a mounting force.

Abstract: In a pressure sensor, a sensor element is mounted on a side of a first surface of a first case, and a second case having a cylindrical hollow portion is bonded to the first case to cover a part of a second surface of the first case, opposite to the first surface. Terminals are embedded in the first case to protrude from the second surface, and branch portions are branched from the terminals from an embedded portion in the first case to have exposed portions exposed to the second surface. A chip capacitor is mounted on the exposed portions on the second surface to be electrically connected to the exposed portions. In the pressure sensor, a diameter (D1) of the second surface of the first case is larger than an inner diameter (D2) of the hollow portion at a position where protrusion top ends of the terminals are positioned.

Abstract: A variable capacitance measuring device can comprise any one or more features in various different embodiments allow a reliable, compact device to be achieved. A capacitor electrode, a gettering housing, and pinch-off connector may be aligned along a common axis may reduce width dimensions without a substantial increase in length. Temperature-induced variations may be reduced by selecting materials that have coefficients of thermal expansion relatively closer to one another. Substantially varying topologies for ceramic-metal interfaces may reduce the likelihood of external contaminants from reaching the evacuated portion of the device. A tube can be used between the capacitor portion and a gettering housing to isolate external forces and getter activation heat from the sensor. The same tube also reduces heat loss from a heated sensor and protects the electronics from overheating. Embodiments also include processes for using and forming the devices.

Abstract: A variable capacitance measuring device can comprise a glass-ceramic insulator having a coefficient of thermal expansion that closely matches the coefficient of thermal expansion of a metallic materials used within the device. The glass-ceramic material may chemically bond to the surfaces of the metallic materials to provide a hermetic seal and eliminate the need for a separate glass seal or grooves within the electrode assembly. Additionally, a single-piece electrode assembly can be used instead of a separate electrode assembly (for the electrical feedthrough) and electrode. A shim may be used during the formation of the insulating material to reduce the likelihood of the insulator adhering to surfaces of the electrode portion during the manufacturing process. Also, separate bake-out and getter activation cycles may be combined into a single heat cycle.

Abstract: A capacitive pressure sensor for measuring a pressure applied to an elastic member includes a capacitive plate disposed adjacent to the elastic member so as to define a gap between a planar conductive surface of the elastic member and a corresponding planar surface of the capacitive plate. The gap, capacitive plate and elastic member together define a capacitor having a characteristic capacitance. The sensor further includes an elongated electrical conductor characterized by an associated inductance value. The conductor is fixedly attached to and electrically coupled with the capacitive plate. The gap between the capacitive plate and the elastic member varies as a predetermined function of the pressure applied to the elastic member so as to vary the characteristic capacitance. The capacitor and the electrical conductor together form an electrical resonator having a characteristic resonant frequency. Varying the capacitance of this tank circuit varies the resonant frequency of the tank circuit.

Abstract: A pressure sensor may include a first membrane that flexes in response to pressure, a reference cavity covered by the first membrane where the reference cavity contains a vacuum and a second membrane, adjacent to the first membrane, the first and second membranes forming a capacitor having a capacitance that varies in accordance with the flexing of the first membrane and the pressure.

Abstract: A pressure sensor element for mounting in a connecting element comprises an isolator body with a laterally projecting membrane. The laterally projecting membrane covering an opening of a passage through which the pressure present at the surface of the membrane is conveyed to a pressure transducer element by means of a hydraulic fluid. In order to mount the pressure sensor element, it is secured in a mounting aperture of the connecting element. The projecting perimeter of the membrane is secured to the surface surrounding the mounting aperture of the connecting element by means of a continuous seam. A membrane type ring in combination with a conventional membrane may be substituted for the projecting membrane, wherein the membrane type ring covers the gap between the pressure sensor element and the adapter element.

Abstract: A transmitter is provided whose operation is not impaired by ambient influences, having a measurement sensor (3), an electronic unit (11) arranged in a housing (1) on a printed circuit board (9), an operating element (15), which can be operated from outside the housing (1), and a transmitting arrangement (19), which transmits a force exerted on the operating element (15) to a switch connected to the electronic unit (11), the switch being a key of a membrane keyboard (23) arranged on the printed circuit board