ABSTRACT
The conversion of mechanical quantities such as pressure to electrical signals for remote readout and recording requires a suitable transducer. To obtain greater sensitivity, solid state silicon-diffused piezoresistive elements have been used, but with some sacrifice in long-term stability. The need for improved accuracy in low-pressure measurements makes it desirable to examine other possible transducer elements. Capacitance and inductance transducers have been used in the past, but require more complex circuitry than the DC voltage used with a resistance bridge, and may offer some stability advantages. The pressure cell used is almost identical physically in size with the 6- to 7-mm strain gauge cuff type transducer that is commercially available. The entire system requires only battery power to obtain the 10 MHz variable oscillation frequency. For the intracranial pressure application, it offers some unique advantages for telemetry because the circuit is so simple.
