Improved mechanical stability of laser-induced graphene electrodes in enzyme-free glucose sensors through transferring to PDMS and partial PDMS etching.

Abstract

The fabrication process and characteristics of flexible glucose sensors using laser-induced graphene (LIG) electrodes and transferring them onto a flexible polydimethylsiloxane (PDMS) film is described. The electrochemical glucose sensor consists of a working electrode, a counter electrode, and a reference electrode, all of which can be fabricated by irradiating a CO₂ laser directly onto a polyimide (PI) film following the designed electrode pattern. This fabrication process allows simple formation of LIG electrode patterns on PI (LIG/PI). These LIG/PI electrodes are quite vulnerable, and hence, those electrodes were transferred onto a slightly melted polydimethylsiloxane (PDMS) and fixed to make LIG/PDMS electrodes with improved robustness. To demonstrate the durability improvement, the LIG/PI and LIG/PDMS electrodes underwent rubbing (once) and bending (100 times) tests for comparison, which shows a substantial improvement with the LIG/PDMS electrodes. An enzyme-free glucose sensor was then fabricated with the LIG/PDMS electrodes and by electroplating Cu onto the LIG/PDMS working electrode as the glucose-sensing electrode. Evaluation of the sensor's electrochemical performance revealed a sensitivity of 7.49 µA/mM·cm².