Laser-induced selective metallization directly preparing repairable superhydrophobic copper layer on polymers and single-droplet ethanol detection

Abstract

Ethanol is widely used in life and ethanol solutions with different concentrations have different uses, so it is important to detect ethanol concentration. Currently, methods for judging ethanol concentration according to the wetting of droplets on the surface of materials are gradually emerging. However, there are still problems, such as the need for measurement equipment, poor accuracy, and cannot be reused. Herein, a novel strategy was proposed to prepare a superhydrophobic (water contact angle = 155.4°) and super-ethanophilic (ethanol contact angle = 5.2°) copper layer on polymer substrate by laser-induced selective metallization (LISM) and atmosphere-induced hydrophobicity, which can be used for single-drop ethanol detection. X-ray photoelectron spectroscopy and Thermogravimetric analysis − Fourier transform infrared − gas chromatography − mass spectrometry showed that when the rough copper layer prepared by LISM was exposed to air, it spontaneously oxidized and adsorbed airborne volatile organic compounds gases to become a superhydrophobic copper layer. The superhydrophobic copper layer obtained by this strategy has good durability. In addition, the superhydrophobic copper layer has excellent repair ability. The ethanol detection array prepared based on this superhydrophobic copper layer can be used to perform single-droplet ethanol detection. The array does not require any equipment and only needs to read the number of droplets in the wetted grid in the 20–70 % ethanol solution concentration range, showing great potential in the field of ethanol detection.