Flexible and Dispense Printed Biopolymer-Gated Organic Electrochemical Transistors for Bioelectronics Applications

Bioelectronics is a field of great interest in which materials and devices are interfaced with biological tissues for both sensing and actuation purposes. This poses significant challenges to the choice of materials, which typically need to possess a wide range of properties such as mechanical flexibility, biocompatibility, (opto-)electronic performance, and easy and low-cost manufacturability. In this work, we demonstrate the potential of using a simple and digital printing method - namely dispense printing - to realize flexible organic electrochemical transistors (OECTs), a device widely employed in bioelectronics. In particular, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) OECTs featuring biopolymers as electrolytes were fully printed on polyimide substrates and tested against KCl-gated transistors. Together with a chitosan-based electrolyte, we present a novel agar-based polymer electrolyte, which exceeded an on-off ratio of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$10^{3}$</tex> in the best case, competing with similar biopolymer alternatives, and outperforming their liquid counterpart.