Laser-induced graphene (LIG) is increasingly gaining importance as a 3D porous graphene material with outstanding properties. Here, LIG structures are realized for electrochemical sensors by patterning polyimide Kapton using a visible 405 nm laser under ambient conditions. The LIG electrodes for flexible electrochemical sensors show a large surface area with a hierarchical porosity distribution along the cross-section.

To optimize the laser parameters, we investigated the electron transfer (ET) kinetics and the electrochemical performance of LIG surfaces produced with an exposure time varied from 10 ms to 50 ms. Characterization of the resulting LIG was performed to understand the correlation between the resulting electrochemical properties and the LIG surface properties by optical microscopy and Raman spectroscopy. The electrochemical properties were evaluated in ferri-ferrocyanide [Fe(CN)₆]^3−/4− by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The highest electron transfer rate constant was registered at an exposure time of 10 ms. However, for an exposure time of 20 ms, the electrochemical behavior is better due to both high surface area and high electron transfer rate constant.

A voltammetric 4-Aminophenol sensor is developed as a proof-of-concept device. It exhibits a good analytical performance realizing a low limit of detection at a level of 9.23 nM in the concentration range from 10 nM to 400 nM. The results demonstrate the suitability of LIG for the development of efficient, disposable, and flexible electrochemical sensors. The developed technological approach supports sustainability while simplifying production and reducing costs.