Bio/CMOS Interfaces for Amperometric Sensing in Voltage Scan

This is the second chapter of this book that deals with Complementary Metal-Oxide Semiconductor (CMOS) design. This chapter addresses CMOS methods that exploit a bias in scanning voltage to drive the Bio/CMOS interface. Initially, the chapter introduces the needs for driving amperometric biosensors with a voltage scan. Some examples of human metabolites that are easier to detect in cyclic voltammetry are then provided. The chapter first introduces a further equivalent model of the electrochemical cell to take into account voltage effects to provide the right electrical behavior in the case of bias variations. The chapter also proposes CMOS methods for generating the voltage ramps that are necessary to acquire data in cyclic voltammetry. The CMOS method introduced in the previous chapter for converting the interface current into a signal frequency is extended to also account here for currents generated by both oxidations and reductions. Further elaborations on the same kind of approach come to CMOS architectures for quasi-digital potentiostats to drive and read the Bio/CMOS interfaces, while several CMOS methods to estimate the metabolite concentration by the faradaic currents are proposed and deeply discussed. The need for dynamic ranges in measuring such faradaic currents is also represented, and related CMOS solutions are learned as well. Finally, the chapter closes with the need for calibration with respect to the samples’ pH at the interface and a CMOS architecture with aim of measuring such a pH. Related multiplexing with the other sensors in the Bio/CMOS interface is also described.