Laser Scribing of Graphene Oxide Using Bessel Beam for Humidity Sensing

Abstract

Laser-scribed graphene oxide (GO) shows great promise for high-performance, cost-effective humidity sensors. However, when using the commonly employed Gaussian beam, the Rayleigh length is relatively short, leading to potential stability issues during large-area processing, especially when defocusing occurs. In this paper, we utilize a diffraction-free Bessel beam to one-step fabricate reduced graphene oxide (rGO) electrodes specifically designed for humidity sensing applications. The effects of defocusing and laser power on the line width and resistance of the fabricated electrodes are investigated, giving the optimal processing parameters for Bessel laser writing of GO. The line width, resistance, and sheet resistance of the rGO electrode are stable at a defocusing distance within ±1.00 mm. Defocusing also proves to be effective in reducing the ablation region during the fabrication process. The temperature and humidity responses of the electrodes are examined, focusing on those fabricated with typical defocusing settings, and the related mechanisms are discussed. Proof-of-principle rGO/GO/rGO humidity sensors are demonstrated, and were one-step fabricated using a Bessel beam with both focusing and defocusing settings. The corresponding humidity response results evidence that rGO humidity sensors can be fabricated using a Bessel beam, even in the defocusing cases. The investigation into the Bessel-beam-based laser fabrication technique offers promising prospects for rapid, flexible, and cost-effective production of graphene-based humidity sensors. Meanwhile, the study of defocusing may enhance the fabrication stability to withstand defocusing conditions effectively.