A Glucose Sensor Based on an Organic Electrochemical Transistor Structure Using a Vapor Polymerized Poly(3,4-ethylenedioxythiophene) Layer

A glucose sensor based on an organic electrochemical transistor (OECT) structure was prepared by vapor phase polymerization (VPP) of 3,4-ethylenedioxythiophene (EDOT). The poly(3,4-ethylenedioxythiophene) (PEDOT) film was introduced as the conducting polymer channel and a platinum wire was used as a gate electrode in the OECT. The redox enzyme glucose oxidase (GOx) was introduced into the electrolyte of the OECT. The sensitivity and detection range of the sensor could be tuned by adjusting the source–drain and gate bias. The OECT showed high sensitivity to glucose in the low concentration region below 10 µM. An acid sensitive fluorescent layer was easily coated on top of the vapor polymerized PEDOT to obtain a double-layered OECT sensor. The optical sensitivity of the double-layered OECT sensor correlated linearly with the electrochemical sensitivity. Furthermore, the fluorescence intensity change of the double-layered OECT sensor was linearly dependent on pH, providing the OECT sensor with dual sensitivity of electrochemical and optical sensitivity.