Ultrafast laser direct writing of screen-printed graphene-based strain electrodes for sensing glass deformation

This study aimed to develop screen-printed graphene-based strain sensors for sensing the deformation of glass. Graphene electrodes of strain sensors with various grid lengths were fabricated by ultrafast laser direct writing. The experimental results revealed that the laser ablation threshold for graphene films was approximately 0.35 J/cm². For areal fluences exceeding 7.8 J/cm², the laser-ablated zone on graphene films served as electrical insulation because the conductive film was completely removed. The optimal laser fabrication parameters for strain sensors were a pulse repetition frequency of 300 kHz, areal fluence of 31.9 J/cm², scan speed of 500 mm/s, line-scan spacing of 0.01 mm, and overlapping rate of laser spots of 94.4%. Laser-formed electrode structures on graphene films had straight edges and sharp corners. Moreover, no residual film and debris existed on the processing paths. During deformation tests on glass substrates with bending distances of 0–180 μm, the strain sensor with a 6-mm grid length exhibited an excellent linear relationship with the change in resistance. Furthermore, the gauge factor of 550.14 for strain sensors with a 6-mm grid length was larger than that of 392.48 and 308.17 for strain sensors with 8- and 10-mm grid lengths, respectively.