Organic electrochemical transistor as an on-site signal amplifier for electrochemical aptamer-based sensing

Abstract

Electrochemical aptamer-based (E-AB) sensors are typically deployed as individual, passive, surface-functionalized electrodes, but they exhibit limited sensitivity especially when the area of the electrode is reduced for miniaturization purposes. We demonstrated that organic electrochemical transistors (OECTs), electrolyte gated tran-istors with volumetric gating, can serve as on-site amplifiers to improve the sensitivity of single electrode-based E-AB sensors. By monolithically integrating an Au working/sensing electrode, on-chip Ag/AgCl reference electrode and Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) counter electrode — also serving as the OECT channel, we can simultaneously perform OECT testing and traditional electroanalytical measurement on E-AB sensors including cyclic voltammetry (CV) and square-wave voltammetry (SWV). This device can directly amplify the current from the E-AB sensor via the in-plane current modulation in the counter electrode/transistor channel. The integrated OECT-based E-AB sensor is able to sense transforming growth factor beta 1 (TGF-β1) with 3 to 4 orders of magnitude enhancement of sensitivity compared to that in a single electrode-based E-AB sensor (292 µA/dec vs. 85 nA/dec for OECT vs. single electrode SWV). This approach is believed to be universal, which can be applied to a wide range of tethered electrochemical reporter-based sensors to enhance sensitivity, aiding in sensor miniaturization and easing the burden on backend signal processing.

A hybrid transistor with transcriptionally controlled computation and plasticity

“…By controlling the bias potential, the kinetics of electron transfer between cells and electrodes could be modulated, providing a means to tune electron transfer to the channel 48 . During our OECT operation, the use of a polarizable Au gate instead of a non-polarizable Ag/AgCl gate could introduce inaccuracies when measuring the channel potential due to capacitive effects on the Au gate and uncertainties in the onset of redox reactions on the gate and channel due to the lack a fixed electrode potential 49,50 . Consequently, to enable precise measurements of the source potential, we used Ag/AgCl pellet pseudoreference electrodes to investigate the de-doping mechanisms.…”

Direct quantification of ion composition and mobility in organic mixed ionic-electronic conductors

“…Organic mixed ionic-electronic conductors (OMIECs) are materials that transport both ions and electrons (1), making them highly versatile for a wide range of applications such as energy storage (2), neuromorphics (3,4), and bioelectronics (5)(6)(7)(8)(9). To guide the development of energy-efficient, high-performance sensors and circuits for these applications, understanding the fundamental operating mechanisms of OMIEC-based devices, in particular the complex mixed ion/ electron transport and coupling within OMIECs, is critical.…”