A PEDOT:PSS‐Based Composite Hydrogel as a Versatile Electrode for Wearable Microneedle Sensing Platforms

Abstract

Advances in biomarker detection have acclaimed a new era of biosensors that enable continuous monitoring of health status, device miniaturization, and wearability. This transition toward integrated, wearable biosensors has necessitated the co‐development of novel materials that can adequately support the operation of these devices. In this study, a novel type of electrode is presented that is suitable for use in wearable electrochemical biosensors. The electrode is constructed using a biocompatible composite hydrogel and takes the form of a hydrogel microneedle (HMN) patch. It is specifically designed for analyzing interstitial fluid. The HMN electrode is a combination of poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), a highly conductive polymer, and graphene oxide, incorporated into a crosslinked hydrogel network of methacrylated hyaluronic acid. To ensure the successful penetration of the skin, the fabrication process is carefully optimized to create sharp needles. To assess the performance of the HMN electrode, electrochemical tests are conducted using an ex vivo porcine skin model. Additionally, HMN electrode's suitability is demonstrated as the working electrode of a wearable electrochemical biosensor for in vivo measurement using a rat model. The findings highlight the advancement of the HMN electrode array as an alternative to solid microneedles, representing the next generation of polymeric electrodes.