Ultra-low LOD H₂O₂ Sensor Based on Synergistic Nernst Potential Effect

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.