Micropower Sensors for Neuroprosthetics

We describe two prototype micropower sensors that potentially help enable neuroprosthetics for the treatment of chronic disease. The first sensor is an EEG instrumentation amplifier for the measurement of neurological field potentials in physiologically relevant bandwidths. The second sensor is a three-axis accelerometer for measuring posture, activity, and tremor. Both sensor interfaces use dynamic offset cancellation techniques-chopper stabilization for the EEG amplifier, correlated-double-sampling for the accelerometer - to reject low frequency excess noise that might otherwise corrupt the key physiological signals. To be compatible with chronic implantation, each sensor interface must operate with less than 2 muW of power from a single battery. Using accepted metrics, these sensors represent the state-of-the-art for noise efficiency.