# Ultra‐low LOD H2O2 Sensor Based on Synergistic Nernst Potential Effect

## TL;DR

A new ultra-sensitive hydrogen peroxide sensor is developed using a stacked polymer layer, enabling detection at extremely low concentrations and potential use in food and biomedical applications.

## Contribution

The novel use of a synergistic Nernst potential effect in a stacked polymer layer achieves an ultra-low detection limit for hydrogen peroxide.

## Key findings

- The sensor achieves an ultra-low detection limit of 1.8 × 10−12 M for hydrogen peroxide.
- The sensor is successfully tested on commercial milk samples to verify reliability.
- The methodology is also demonstrated for glucose detection with a limit of 8.82 × 10−11 M.

## Abstract

The food processing industry and biomedical science research are relying on the low limit of detection (LOD) for hydrogen peroxide (H2O2). Organic electrochemical transistors (OECTs) are excellent for biochemical sensing applications due to their excellent signal amplification capability. The paper describes  a way of detecting H2O2 through the use of stacked poly(3,4‐ethylenedioxythiophene): bromothymol blue (PEDOT: BTB)/poly(3,4‐ethylenedioxythiophene): polystyrene sulfonate (PEDOT: PSS) as the semiconducting channel of the OECT. The H2O2 sensor presents an ultra‐low LOD, down to 1.8 × 10−12 M, due to the synergistic effect of the Nernst potential generated by the platinum gate electrode catalyzing H2O2 and the Nernst potential generated by the interaction between BTB molecules and hydrogen ions, the by‐product of H2O2 catalysis. A microsystemwith a signal processing circuit and a mobile app for the sensor has been developed, and they are then tested on commercial milk samples to verify their reliability. Since the majority of enzyme‐catalyzed reactions generate or use H2O2 in biochemical reactions, the methodology is applicable not only to the detection of H2O2 but also to the detection of analytes based on enzyme‐catalyzed reactions. For demonstration, glucose detection with a LOD of down to 8.82 × 10−11 M is also presented.

Due to the synergistic effect of ENernst,H2O2 and ENernst,H+, the proposed sensors in this study can achieve ultralow H2O2 detection limit as low as 1.8 × 10−12 M based on the stacked PEDOT: BTB/PEDOT: PSS semiconducting layer. Furthermore, this innovative approach to reducing LOD is also broadly applicable to analytes detected via enzyme‐catalyzed reactions.