Apparatus for determining the actual status of a piezoelectric sensor in a medical implant

An apparatus for providing a signal representing a status of a sensor in a medical implant, comprising:

• a sensor which generates positive and negative charges respectively in response to positive and negative changes in a load, selected from the group consisting of acceleration forces, gravitational forces and pressure, acting on said sensor;
• a circuit for detecting all positive and negative charges generated by said sensor and, after detecting said charges, for removing substantially all of said generated positive and negative charges from said sensor, for maintaining an accumulated charge potential of said sensor at a substantially zero level, and for generating a sensor output current from said detected positive and negative charges;
• an integrator supplied with said sensor output current which integrates said sensor output current to produce an integrated signal representing a status of said sensor;
• and
• said integrator including a current-to-frequency converter which converts said sensor output current into a frequency signal having a frequency representing a level of said sensor output current, and a counter supplied with said frequency signal for subjecting said frequency signal to a counting operation to obtain said integrated signal.