Cation Discrimination in Organic Electrochemical Transistors by Dual Frequency Sensing

TL;DR

This study introduces a dual-frequency impedance sensing method in organic electrochemical transistors to quantitatively and specifically discriminate different cations based on their unique impedance signatures, enhancing bioelectronic analysis.

Contribution

The paper presents a novel dual-frequency impedance sensing strategy in a single OECT device for specific cation discrimination, advancing bioelectronic sensing capabilities.

Findings

Impedance governed by channel dedoping at low frequency.

Electrolyte gate capacitive coupling dominates at high frequency.

Cation-specific impedance signatures enable discrimination.

Abstract

In this work, we propose a strategy to sense quantitatively and specifically cations, out of a single organic electrochemical transistor (OECT) device exposed to an electrolyte. From the systematic study of six different chloride salts over 12 different concentrations, we demonstrate that the impedance of the OECT device is governed by either the channel dedoping at low frequency and the electrolyte gate capacitive coupling at high frequency. Specific cationic signatures, which originates from the different impact of the cations behavior on the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) polymer and their conductivity in water, allow their discrimination at the same molar concentrations. Dynamic analysis of the device impedance at different frequencies could allow the identification of specific ionic flows which could be of a great use in bioelectronics to further interpret complex mechanisms in biological media such as in the brain.