| abstract |
A fluidtight, hermetically sealed, miniature transducer adapted to be inserted into the human body and useful for directly monitoring internal fluid or pneumatic pressures within the human body is disclosed. Semiconductor strain gauge elements constituting a piezoresistive bridge are formed by diffusion on the surface of one side of an integral flexible, rectangular, silicon diaphragm area of a single crystal silicon base. A single crystal silicon cover is eutectically bonded to the base by a metallic laminate seal. The base, cover, and seal define an evacuated fluidtight chamber containing the strain gauge elements. Electrical conductors, which include diffused conductor paths under an insulating oxide layer, extend from the piezoresistive bridge to contact pads outside the fluidtight chamber. The contact pads can be connected to a readout device for electrically measuring the pressure differential between the evacuated chamber and fluid external to the transducer as a function of time. |