Ultra‐low LOD H ₂ O ₂ Sensor Based on Synergistic Nernst Potential Effect

Abstract The food processing industry and biomedical science research are relying on the low limit of detection (LOD) for hydrogen peroxide (H ₂ O ₂ ). Organic electrochemical transistors (OECTs) are excellent for biochemical sensing applications due to their excellent signal amplification capability. The paper describes a way of detecting H ₂ O ₂ 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 H ₂ O ₂ 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 H ₂ O ₂ and the Nernst potential generated by the interaction between BTB molecules and hydrogen ions, the by‐product of H ₂ O ₂ 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 H ₂ O ₂ in biochemical reactions, the methodology is applicable not only to the detection of H ₂ O ₂ 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.