Abstract: There is disclosed a balancing network for a piezoresistive semiconductor bridge configuration. The balancing network comprises a plurality of series resistors arranged in series with the sensing elements in the bridge configuration. Each resistor differs from the previous one according to a power of two to form a binary ladder arrangement. The individual resistors are associated with terminals to allow the transducer manufacturer to selectively short one or more resistors to provide zero balance compensation. The resistors are located on the nonactive portion of the semiconductor substrate and are fabricated by the same techniques employed for fabrication of the semiconductor piezoresistive sensing elements to assure temperature tracking of the unit with the desired temperature operating range.

Abstract: An improved deformable flexure element (10) for use in strain gage tranducers and a process for making the element are disclosed. By appropriate selection of materials and gage geometries in accordance with the invention, the zero and span temperature coefficients of the transducer are reduced substantially to zero. Improved processes for producing such flexure elements are disclosed.

Abstract: A semiconductor pressure sensor employing the piezoresistive effect of single crystal silicon resistors to measure the flexure of a semiconductor diaphragm. In the preferred embodiment, a Wheatstone bridge composed of a first pair of resistors disposed on the center of the diaphragm and a second pair of resistors disposed on the periphery of the diaphragm is employed. Due to the nature of the diaphragm flexure, the first and second pairs of resistors exhibit piezoresistivity in opposite directions enabling pressure measurement with greater sensitivity. The diaphragm is mounted on and supported by a silicon clamp ring. The diaphragm and the clamp ring together form a unitary semiconductor structure.

Abstract: A pressure transducer has at least one pressure transmitting space filled with liquid, a space for a pressure to be sensed connected to the pressure transmitting space through a diaphragm, and a pressure sensitive element in the pressure transmitting space for transducing a pressure transmitted from the space for the pressure to be sensed to the pressure transmitting space through the diaphragm to an electrical signal. A printed circuit board wired to electrically connect terminals of the pressure sensitive element is arranged closely to the element and thin temperature sensitive elements for temperature-compensating the pressure sensitive element are arranged on the printed circuit board.

Abstract: A temperature compensated piezoresistive transducer includes a silicon body having a major top surface and an under surface. The body has generally parallel spaced first and second elongate slots formed therein extending through said top and under surfaces to define a center portion between said slots and first and second outer portions at the outward edge of the respective slots. The center portion is adapted to receive pressure to be measured. The body has an additional slot extending through the top and bottom surfaces and extending around the first, second and center portions to define the outer periphery of a transducer membrane with portions of the body remaining to integrally support the membrane. Plural piezoresistive elements having elongate and transverse dimensions are formed on the membrane. The elements are arrayed to receive compressive and tensile stress when pressure is applied.

Abstract: Subterranean earth formations containing energy values are subjected to hydraulic fracturing procedures to enhance the recovery of the energy values. These fractures are induced in the earth formation by pumping liquid into the wellbore penetrating the earth formation until the pressure of the liquid is sufficient to fracture the earth formation adjacent to the wellbore. The present invention is directed to a transducer which is positionable within the wellbore to generate a signal indicative of the fracture initiation useful for providing a timing signal to equipment for seismic mapping of the fracture as it occurs and for providing a measurement of the pressure at which the fracture is initiated.