Improvements on pH Sensitivity of ISFETs Based on Multiphysics Coupling

Abstract

ISFET is one of the most promising BioFETs due to its obvious advantages in pH sensing compared with traditional glass electrode. The increasing requirements on the pH detecting machine leads to the need of increasing the sensitivity of the ISFET. So, the main target in this paper is to find some parameters to help increase the sensitivity of MOSFET for biological and medical detection. COMSOL is used to make the model of the MOSFET since its good performance on Multiphysics coupling. The model consists of one semiconductor domain and one electrolyte domain. Based on the operational mechanism of ISFET and the surface reaction between gate insulator and electrolyte, temperatures, charge density, intrinsic buffer capacity and the differential capacity was set to find optimal sensitivity of the ISFET. The target solution is in Controlled Room Temperature (CRT) Storage. As the temperature rises from 298.15K to 313.15, the surface site density rises from 518 1/m2 to 21019 1/m2 and the thickness of Stern Layer rises from 510–10 m to 4.510-9 m, the sensitivity can increase about 4.37%,6.43%,8.72% respectively, with optimal sensitivity about 63.3mV, 64.2mV and 65.6mV per pH.