AC amplification gain in organic electrochemical transistors for impedance-based single cell sensors

Abstract

Research on water-gated and organic electrochemical transistor (OECT) architectures is motivated by the prospect of a highly biocompatible interface capable of amplifying bioelectronic signals at the site of detection. Despite many demonstrations in these directions, a quantitative model for OECTs as impedance biosensors is still lacking. We overcome this issue by introducing a model experiment where we simulate the detection of a single cell by the impedance sensing of a dielectric microparticle. The highly reproducible experiment allows us to study the impact of transistor geometry and operation conditions on device sentivity. With the data we rationalize a mathematical model that provides clear guidelines for the optimization of OECTs as single cell sensors, and we verify the quantitative predictions in an in-vitro experiment. In the optimized geometry, the OECT-based impedance sensor allows to record single cell adhesion and detachment transients, showing a maximum gain of (20.2±0.9) dB with respect to a single electrode based impedance sensor.

Organic electrochemical transistors as on-site signal amplifiers for electrochemical aptamer-based sensing

“…This equation describes the amplification properties of an OECT to the integral of I G , which complements the OECT amplification work of others. For example, the work by Braendlein et al reports on the use of OECT to amplify input voltage in a voltage amplifier circuit with load resistance 41 , and Bonafe et al shows OECT amplification of AC current signal in the capacitive-dominated regime 42 . The equation also shows that the amplification factor is highly related to the materials figure-of-merit and the geometry, which indicates that we can further enhance the amplification factor by using organic mixed ionic-electronic conductors (OMIECs) active channel with higher mobility and designing the channel with short length.…”