Most of the techniques used for micro and nano-patterning currently are of high quality and reproducibility, but they require expensive equipment and involve many time-consuming steps to achieve the desired results. We herein report a patterning method of conducting layers on breathable substrates using a fast, simple, and mask-less laser engraving technique. A resolution in the range of 30 lm has been successfully achieved in this report. The method is fast and the pattern can be easily changed or redesigned within a few minutes. The patterning time for a 25 cm2 sample is approximately 3 minutes. In comparison, patterning a sample of the same size using photolithography requires up to 4 hours. In this manuscript, we describe the laser patterning process, how to improve the patterning resolution, the calibration steps involved as well as an application for organic electrochemical transistors as gas sensors for detecting oxygen or sulphur dioxide.