Temperature compensation electronics for ISFET readout applications

This paper presents temperature compensation electronics for ion sensitive field effect transistor (ISFET) sensors. It consists of a bridge-type floating-source ion sensing circuit and a VT extractor centigrade temperature sensor accompanied with a temperature coefficient (TCF) cancellation method. Using LabVlEW packages has developed an extended measurement system including compensation algorithms programming. Experimental results show that the temperature dependence of the Si/sub 3/N/sub 4/-gate ISFET sensor improved from 8mV//spl deg/C to near 0mV//spl deg/C with the proposed temperature compensation circuitry. This system allows a wide range of high accurate pH-level measurements. The method of temperature compensation may also be valid for other biosensors or bioFETs.