摘要:
A pressure sensor including: a deflectable diaphragm including a substantially central boss and channel; and, an optical waveguide having first and second arms, wherein the first arm is substantially aligned with an edge of the boss and the second arm is substantially aligned with an edge of the channel.
摘要:
A low cost sensor assembly for measuring oxygen pressures contains a transistor header. The transistor header has terminal pins extending therefrom. The transistor header co-acts with a first circuit insulator board. The first circuit board has deposited thereon four hand mirror shaped contact areas each one associated with one of the terminal pins of the transistor header. The top portion of each contact areas has an aperture with the extending arm of the area directed towards the center of the board. The board is epoxied to the transistor header with the terminal pins of the header extending into the apertures of the contact board. A second contact board is then epoxied to the first contact board. The second contact board has a series of four apertures located at the center. Each of the apertures of the second board contacts the handle portion of the mirror patterns of the first board. A leadless piezoresistor sensor assembly is then positioned and secured to the second board whereby the terminals from the sensor assembly align with each of the apertures in the second board. The terminals of the sensor assembly are apertures filled with a conductive glass metal frit and each filled aperture makes contact with a terminal of the sensor. The configuration has all conductive terminals of the entire device completely isolated and insulated from the oxygen environment, thus preventing ignition of the oxygen.
摘要:
A high temperature pressure transducer is fabricated from silicon carbide. A wafer of silicon carbide has reduced or active areas which act as deflecting diaphragms. Positioned on the reduced or active area is a silicon carbide sensor. The sensor is secured to the silicon carbide wafer by a glass bond. The pressure transducer is fabricated by first epitaxially growing a layer of highly N-doped 3C silicon carbide on a first silicon wafer or substrate. A second wafer of silicon carbide is selected to be a carrier wafer. The carrier wafer is etched preferentially to produce the deflecting members or reduced areas which serve as diaphragms. The 3C material on the silicon slice is patterned appropriately to provide a series of individual piezoresistors which then may be interconnected to form a Wheatstone bridge. The two wafers are joined together using a high temperature glass frit, such as a pyroceram, with the various resistor elements appropriately placed over the deflecting members of the silicon carbide wafer. The silicon on the silicon wafer is removed and various metallic contacts and interconnects are formed on the 3C silicon carbide resistor network.
摘要:
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.
摘要:
An ultra high temperature hermetically protected transducer includes a sensor chip having an active area upon which is deposited piezoresistive sensing elements. The elements are located on the top surface of the silicon wafer chip and have leads and terminals extending from the active area of the chip. The active area is surrounded with an extending rim or frame. The active area is coated with an oxide layer which passivates the piezoresistive sensing network. The chip is then attached to a glass pedestal, which is larger in size than the sensor chip. The glass pedestal has a through hole or aperture at each corner. The entire composite structure is then mounted onto a high temperature header with the metallized regions of the header being exposed to the holes in the glass pedestal; a high temperature lead is then bonded directly to the metallized contact area of the sensor chip at one end. The leads are of sufficient length to extend into the through holes in the glass pedestal. A sealing cover is then attached to the entire composite sensor to hermetically seal all of the interconnections. The sealing cover is a glass structure, has a central aperture which corresponds to the aperture formed by the frame, allowing the active area of the sensor to be exposed to the pressure medium. The sealing cover is bonded to the periphery of the rim and to the glass supporting pedestal.
摘要:
Semiconductor devices useful in high temperature sensing applications include a silicon carbide substrate, a silicon dioxide layer, and an outer layer of crystalline doped silicon carbide. The device is a 3C—SiC/SiO2/SiC structure. This structure can be employed to fabricate high temperature devices such as piezoresistive sensors, minority carrier devices and so on. The crystalline doped silicon carbide is dielectrically isolated from the substrate. The devices are formed by processes that include bonding a pattern wafer to a substrate wafer, selective oxidation and removal of undoped silicon, and conversion of doped silicon to crystalline silicon carbide. The level of doping and the crystalline structure of the silicon carbide can be selected according to desired properties for particular applications.
摘要:
A thin layer of ionic crystal is grown on a substrate. The crystal could be any type of ionic crystal, such as sodium chloride or potassium chloride. The crystal is a pure form of the chosen compound and may contain contaminants which would shift the wavelength of created color centers. On top of the first crystal layer, a second thin layer of a different type of crystal is deposited, such as lithium fluoride or sodium fluoride. When these two layers are radiated with gamma rays, they will each form color centers at the spots radiated. Because of the difference in crystalline properties of the two different ionic crystal centers, their color centers would be at different wavelengths. Each of the two separate ionic crystals will emit light at different characteristic wavelengths when illuminated at their unique absorption frequencies. Each layer can be made to lase separately. The top layer has an absorption energy greater than that of the bottom layer, so that the layer energy of the bottom layer absorption peak will pass through the top layer and be absorbed only by the bottom layer. There are many ways of forming F-centers in the two superimposed layers, such as by the use of selective gamma radiation by heating of an anion layer of the particular compound and then depositing the second ionic crystal on the first ionic crystal and then depositing an anion layer on the second crystal and then heating to produce a structure which will lase it to the different frequencies.
摘要:
An oil filled pressure transducer of the type employing a metal diaphragm has a diaphragm of a greater thickness than a conventional diaphragm. The thick diaphragm exhibits and accommodates extremely large pressures and deflects to cause a lower pressure to be transmitted to the oil. Because of the large thickness of the metal diaphragm, the diaphragm dissipates a predetermined percentage of the applied pressure, whereas a corresponding fraction of the applied pressure is transmitted to the oil and hence to the silicon sensors. In this manner the diaphragm acts as a step-down transformer where a portion of the force or pressure applied to the diaphragm is transmitted to the pressure sensor. The pressure sensor receives a pressure which is a fraction of the applied pressure and the sensor is compensated to produce an output proportional to the actual pressure as applied to the thick diaphragm.
摘要:
A force transducer assembly for measuring compressive and tensile loads applied to a force transmission device, the assembly includes a housing, a sleeve assembly and a sensor device. The housing has a hollow interior. The sleeve assembly is coupled within the interior of the housing. The sensor device is secured within the interior of the housing between a portion of the sleeve assembly and a portion of the housing. The sensor device includes first and second sensors each including an isolation diaphragm at least partially defining an oil-filled cavity, and a piezoresistive sensor positioned so as to be effected by a change in pressure in the oil-filled cavity. When a first force is applied to the apparatus in a first direction via the force transmission device, one of the isolation diaphragms is deflectable in response thereto, and when a second force is applied in a second direction opposite to the first direction, the other of the isolation diaphragms is deflectable in response thereto. This causes a corresponding output from the sensor assembly. The first direction exerts a push on the device and the second direction exerts a pull on the device.
摘要:
A pressure sensing device for producing an output proportional to an applied pressure irrespective of vibration and acceleration of the device, the device including: a first deflecting diaphragm formed in a first wafer and including a first plurality of piezoresistors mounted thereon, the first diaphragm being responsive to the applied pressure and vibration of the device; and, a second deflecting diaphragm formed in the first wafer and including a second plurality of piezoresistors mounted thereon, the second diaphragm being responsive only to vibration of the device; wherein, the first and second pluralities of piezoresistors are electrically coupled together to provide a common output such that they cooperatively at least partially cancel a portion of the common output associated with the vibration of the device.