Organic Electrochemical Transistors Printed via Inkjet Technology for Bio-Interfacing Applications

Abstract

Organic Electrochemical Transistors (OECTs) are experiencing rapid growth in biomedical applications, becoming increasingly integral to bio-electronic interfaces. Traditionally, high-performing OECTs are fabricated in cleanrooms using cumbersome and costly multistep photolithography, spin-coating, and lift-off processes. These methods complicate and limit their integration with chemically and thermally sensitive materials. In contrast, drop-on-demand inkjet printing has emerged as a highly promising alternative, offering versatility and precision. The objective of this thesis is to develop and optimize inkjet-printed OECTs for molecular sensing and electrophysiological monitoring applications. We systematically fabricate and characterize these inkjet-printed OECTs by varying their geometrical parameters, including the width, length, and thickness of their active channels. Comprehensive analyses of their electrical properties will be conducted, focusing on current-voltage characteristics, amplification capabilities, response times, and cut-off frequencies. High-speed and flexible devices will be utilized to record electrocorticography signals in vivo in a rat model, particularly for the detection of epileptic seizures. Additionally, high-amplifying and ultra-stable OECTs will be employed to detect circulating heart failure biomarkers. This research aims to establish reliable fabrication protocols and demonstrate the broad applicability of inkjet-printed OECTs in various biomedical domains. We aim to develop an inkjet fabrication protocol that produces biosensors with high stability and reproducibility, achieving performance metrics comparable to those of photolithographed devices. Our discussion includes the metrics required for successful integration in various bio-interfacing applications. We show that bench-top inkjet printers can effectively fabricate high-performing OECTs, providing a reproducible solution for diverse bioelectronic interfacing applications, from molecular sensing to electrophysiological monitoring. All in all, this work streamlines OECT integration into bioelectronic platforms, expanding their applicability across biomedical domains.