Stability study of Pt as reference electrode for ISFETs operating in reference electrolyte

摘要

Pt electrode used as reference electrode (RE) of Ion Sensitive Field-Effect Transistor (ISFET) is controversial with respect to its redox reactions with the electrolyte so that its potential can be easily perturbed by compositional changes or the flow of electrolyte. The microfluidic-controlled Pt-KCl RE system (PtRE) has been previously proposed to potentially replace the conventional RE for specific applications. This paper presents our further study on the stability of Pt electrode as ISFET's RE using the PtRE system. It is found that the potential of Pt electrode preserved in air is not stable in the beginning and drifts slowly for quite a few minutes. However, by immersing the Pt electrode in KC1 reference electrolyte for a certain time prior to test, the reference characteristics of the Pt electrode can be greatly improved and exhibit as almost good stability performance as conventional Ag/AgCl electrode. Hence, Pt electrode in the PtRE system can be used as a viable alternative to conventional RE for ISFETs and other biochemical sensors.