This work aims to show the feasibility of an innovative approach for the manufacturing of organic-based devices with a true three-dimensional and customizable structure that is made possible by plastic templates, fabricated by additive manufacturing methods, and coated by conducting organic thin films. Specifically, a three-dimensional prototype based on a polyamide structure covered by poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) using the dip-coating technique demonstrated a multifunctional character. The prototype is indeed able to operate both as a three-terminal device showing the typical response of organic electrochemical transistors (OECTs), with a higher amplification performance with respect to planar (2D) all-PEDOT:PSS OECTs, and as a two-terminal device able to efficiently implement a resistive sensing of water vaporization and perspiration, showing performances at least comparable to that of state-of-art resistive humidity sensors based on pristine PEDOT:PSS. To our knowledge, this is the first reported proof-of-concept of a true 3D structured OECT, obtained by exploiting a Selective laser sintering approach that, though simple in terms of 3D layout, paves the way for the integration of sensors based on OECTs into three-dimensional objects in various application areas.
Keywords: 3D-printed electronics; biosensor; multifunctional operation; organic electrochemical transistor.