Laser direct writing of graphene quantum dots encircling conductive structures for stimuli-responsive anti-counterfeiting label

Graphene quantum dots (GQDs) are fluorescent materials whose fluorescence intensity changes in response to external stimuli. In this study, we demonstrated the fabrication of a semi-cylindrical conductive microstructure encircled by GQDs on polydimethylsiloxane in a single step by laser carbonization. By adjusting laser parameters, structures with different resistance values were selectively fabricated. Under the voltage application to the structure, Joule heating in low-resistance structures led to a decrease in GQDs fluorescence intensity, while high-resistance structures showed minimal changes. Combining these structures enabled voltage-responsive anti-counterfeiting labels, readable only under excitation light and voltage. The proposed method enables one-step fabrication of voltage-responsive structures by laser irradiation, thereby paving the way for the development of voltage-controlled anti-counterfeiting technology.