A laser-induced graphene-based bipolar electrode sensor for colorimetric detection of glucose

Abstract

Laser-induced graphene (LIG) has been widely employed as a flexible, highly conductive substrate for wearable electrochemical sensors. Here, we adapt LIG for direct colorimetric sensing by incorporating it into a bipolar-electrode (BPE) architecture. Indium tin oxide nanoparticles deposited on the LIG surface render the oxidation-state-dependent color transition of polyaniline visible to the naked eye. In this configuration, electrochemical signals generated at the BPE detection pole are converted into immediate color shifts at the reporting pole, enabling visual detection of analytes such as hydrogen peroxide and glucose. The BPE design reduces device complexity, and in combination with polydimethylsiloxane (PDMS) microchannels, yields a lightweight, fully flexible sensor ideal for wearable applications. This work expands the scope of LIG towards colorimetric sensing and demonstrates a strategic path towards wearable, point-of-care devices. © 2025 Elsevier B.V.