A Novel AC Wheatstone Bridge-Based Analog Interface for RC Biosensor Applications

In this paper, a novel electronic interface circuit for RC biosensor applications is proposed and analyzed. The circuit is based on the self-balancing Wheatstone bridge, which allows for a larger dynamic range with respect to traditional bridge methods. Differently from similar previously proposed solutions that operate with purely resistive or capacitive sensors, the circuit is meant to be used with a biosensor that has a more elaborated RC equivalent circuit. In particular, it is shown that, under certain conditions discussed in the text, the system is able to measure the resistance value of the equivalent circuit of this sensor. The operation of the circuit is described in detail, as well as the results and measurements performed on a practical discrete-component implementation of the circuit.