An Integrated Control and Readout Circuit for Implantable Multi-Target Electrochemical Biosensing
We describe an integrated biosensor capable of sensing multiple molecular targets using both cyclic voltammetry (CV) and chronoamperometry (CA). In particular, we present our custom IC to realize voltage control and current readout of the biosensors. A mixed-signal circuit block generates sub-Hertz triangular waveform for the biosensors by means of a direct-dig- ital-synthesizer to control CV. A current to pulse-width converter is realized to output the data for CA measurement. The IC is fabricated in 0.18 μm technology. It consumes 220 μW from 1.8 V supply voltage, making it suitable for remotely-powered applications. Electrical measurements show excellent linearity in sub-μA current range. Electrochemical measurements including CA measurements of glucose and lactate and CV measurements of the anti-cancer drug Etoposide have been acquired with the fabricated IC and compared with a commercial equipment. The results obtained with the fabricated IC are in good agreement with those of the commercial equipment for both CV and CA measurements.