Organic electrochemical transistors have emerged as a promising
alternative to traditional 2/3 electrode setups for sensing applications,
offering in-situ transduction, electrochemical amplification, and noise
reduction. Several of these devices are designed to detect
potentiometric-derived signals. However, potentiometric sensing should be
performed under open circuit potential conditions, allowing the system to reach
thermodynamic equilibrium. This criterion is not met by conventional organic
electrochemical transistors, where voltages or currents are directly applied to
the sensing interface, that is, the gate electrode. In this work, we introduce
an organic electrochemical transistor sensing configuration called the
potentiometric‑OECT (pOECT), which maintains the sensing electrode under open
circuit potential conditions. The pOECT exhibits a higher response than the
2-electrode setup and offers greater accuracy, response, and stability compared
to conventional organic electrochemical transistors. Additionally, it allows
for the implementation of high-impedance electrodes as gate/sensing surfaces,
all without compromising the overall device size.