Encapsulated transducer assembly

Claim 1

In combination: a casing including a transducer receiving portion and a fluid receiving portion for maintaining a fluid; an electromechanical transducer assembly mounted on a diaphragm secured within said transducer-receiving portion and having a very low-frequency cutoff comprising a transducer member disposed adjacent said diaphragm comprising a piezoelectric material for providing an electrical output in response to a mechanical input thereto imparted through said fluid; an amplifier circuit mounted on said transducer member and including, an active element including input and output electrodes, said active element comprising a field effect transistor of the metal oxide silicone type and including a gate electrode corresponding to said input electrode and source and drain electrodes corresponding to said output electrodes; an elastomer disposed over said amplifier circuit and said transducer member for encapsulating them, said elastomer having a high resistivity to prevent low-impedance paths from developing in and around said transducer member and said amplifier circuit and having such an elasticity to permit said transducer member to be sensitive to said mechanical input; means for applying said electrical output of said transducer member to said input electrode, means for applying operating potentials to said amplifier circuit passing through said elastomer to appear external thereof; and means for providing output electrical signals at one of said outpuT electrodes passing through said elastomer to appear external thereof in response to said mechanical input.