Analysis of output characteristics of ion sensitive field effect transistor based biosensor for measurement of pH in biochemical solutions

The need for improved system’s response time, sensitivity, selectivity and miniaturization has continued to form the premise for focusing research attention on innovative design and development of biochemical sensors. Ion sensitive field effect transistor (ISFET) can be used to innovatively drive biochemical sensors for the measurement of concentration of ions and molecules in solutions.  This simulation study focuses on the determination of output characteristics of ISFET pH sensor as applied in the measurement of concentration of hydrogen potential (pH) which is a function of the proton concentration in an analyte solution. The pH of a target analyte interacts with the ion sensitive membrane of ISFET to produce charges which in turn changes the potential of the working electrode of the sensor.  The output characteristic of interest is the gate voltage of ISFET which is a function of pH concentration of analyte under study. The relationship between the sensor’s input pH concentration and its output gate voltage describes the sensitivity of the device.  From the results obtained from the study, as the input pH concentration was increased from 5 to 11, the output gate voltage ISFET pH sensor increased from 2.65 V to 2.9 V.