Patent ID: 8400169

Claim:
A capacitive sensor for measuring a small biomedical electrical charge originating from an object under test comprising: input circuit elements configured for sensing the charge to provide an output signal that is a function of the charge being measured, wherein the input circuit elements comprise an electrode for sensing the charge originating from the object and a first resistance element electrically connected to the electrode; and wherein the electrode has no electrical contact with the object; amplification circuit elements connected to the input circuit elements and configured for amplifying the output signal; processing circuit elements configured for receiving and processing the amplified output signal and for providing the measurement; and conditioning and monitoring circuit elements coupled to at least the input circuit elements comprising monitoring circuit elements and conditioning circuit elements, the conditioning circuit elements comprising a second resistance element connected to a switch; wherein the monitoring circuit elements are configured for monitoring the amplified output signal to detect an error in a measurement that is greater than a preset value caused by charge buildup on the electrode, and wherein the conditioning circuit elements are configured to be activated for discharging the electrode when the error in the measurement is detected by the monitoring circuit elements and the conditioning circuit elements are configured to be deactivated when the error in the measurement is no longer detected, and wherein the switch is connected to ground potential for discharging the electrode the switch configured such that in the closed position the conditioning circuit elements are activated and in the open position the conditioning elements are not activated.