Ultra-Low Hydrogen Peroxide Detection via Synergistic Nernst Potential Effect in Organic Electrochemical Transistors

The organic electrochemical transistor (OECT)-based synergistic Nernst potential-generated via the Pt gate electrode catalyzing hydrogen peroxide (H2O2) and the interaction between bromothymol blue (BTB) molecules and hydrogen ions (the by-product of H2O2 catalysis)-is leveraged for the ultra-low detection of H2O2 down to 1.8 × 10^-12 M, with a broad linear detection range from 10^-11 M to 10^-3 M. The formation of this potential is determined by selecting a source-drain voltage (VDS) and a gate voltage (VG) of -0.6 V as the optimal operating points, and by adopting the stacked-layer poly(3,4-ethylenedioxythiophene):bromothymol blue/poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:BTB/PEDOT:PSS) as the semiconducting channel material. In addition, relevant verification is provided by characterizing the carrier (de)doping capability of the stacked layers using UV-vis spectroscopy, identifying the optimal operating point via electrochemical measurements, and evaluating the sensing performance of the as-constructed OECT-based H2O2 sensor using single-stage constant-voltage scanning. Finally, the OECT-based H2O2 sensor is fabricated via a micro-nano manufacturing process, including the preparation of stacked semiconducting layers by spin-coating and the fabrication of microelectrodes via the lift-off process and magnetron sputtering. This methodology can open a broad avenue for the ultra-low detection of analytes through enzyme-catalyzed reactions.