Reconfiguration of organic electrochemical transistors for high-accuracy potentiometric sensing
Luca Salvigni, Prem D. Nayak, Anil Koklu, Danilo Arcangeli, Johana Uribe, Adel Hama, Raphaela Silva, Tania Cecilia Hidalgo Castillo, Sophie Griggs, Adam Marks, Iain McCulloch, Sahika Inal
Abstract
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. The translation of transistor-based sensor technologies is limited by unreliable potentiometric sensing. Here, the authors propose a transistor configuration that eliminates the measurement inaccuracies associated with electrochemical transistor-based potentiometric sensors.