Towards a miniature implantable in vivo telemetry monitoring system dynamically configurable as a potentiostat or galvanostat for two- and three-electrode biosensors

A miniature implantable and dynamically configurable potentiostat and galvanostat for two- and three-electrode biosensors with a telemetry electronics package was developed to provide remote monitoring of implantable amperometric and voltametric biosensors such as for glucose. Included are circuitry for sensor biasing, a transimpedance amplifier to produce the sensor proportional output signal, and a transceiver (transmitter and receiver) which can both receive setup parameter values and transmit the biosensor concentration data to a corresponding remote transceiver and computer for monitoring. Remotely configurable features included in the in vivo implanted unit include: sensor excitation changes; filter frequency cutoff values, amplifier gain; and transmission intervals utilizing 303.825-MHz UHF RF telemetry for end-to-end remote data monitoring. The developed mP/Gstat printed circuit board measures about 51/spl times/22/spl times/1mm thick, and is suitable for bench top or encapsulated use. Instrumentation developed in this paper will allow other researchers to develop implantable units. Evaluation in two- and three-electrode mPstat and two electrode mGstat modes with simulated biosensors showed overall average theoretical to actual recorded value differences of only 0.5859% reading (RDG) with a standard deviation (SD) of 0.5376% indicating excellent design performance. System testing in two-electrode mPstat mode with actual glucose sensors showed excellent stability and correlation to standard biosensor calibrations with an average difference of only 7.33% full scale (FS) with 3.65% SD, which is minimal considering two totally independent calibration instrument configurations.