St. Jude Medical Ab

Lars Landelius

Kenth A Nilsson

Johan Lidman

Charlotte Kjellman

In an apparatus for determining the actual status of a piezoelectric sensor in a medical implant, electrical charges generated in the sensor, in response to changes in acceleration and/or gravitational force or other loads acting on the sensor, are continuously detected and the charges are then removed from the sensor, thereby maintaining the voltage across the sensor at a substantial constant zero level. The detected charges, both negative and positive, are integrated, thereby providing a resulting integrated signal representing the actual status of the sensor. The integrated signal is then evaluated for determining the physical activity and/or the posture of a patient in whom the medical implant is implanted.

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Järfälla, Sweden

Lars Landelius