Biocompatible Hydrogel Modified Silicon Nanowire Field Transistor for Highly Sensitive pH Detection

Abstract In this work, a silicon nanowire field-effect transistor (SiNW FET) device was developed and applied to pH sensing. A hydrogel was synthesized by radical polymerization as the dielectric and functional layer of SiNW FET. The spin coating process of the hydrogel was defined through different rotating speed. The results revealed that the suitable glue mixing process was determined to be 500 rpm/min at low speed and 4500 rpm/min at high speed. We demonstrated the effect of pH solutions on the sensitivity of the SiNW FET sensor modified by hydrogel. The SiNW FET sensor was used to detect a solution pH ranging from 5 to 11, with the response current increasing stepwise as the pH value increased. Compared with SiNW FET, the hydrogel-coated SiNW FET had higher sensitivity and time response rate for pH sensing. The obtained results demonstrated that modification of hydrogels can significantly increase the pH sensing properties of SiNW FET.