Femtosecond laser induced direct patterning for liquid-metal repellent surface

Patterning liquid metal is a promising electrode material for soft electronics. In order to obtain controllable and fine liquid metal patterning, in this study, a superhydrophobic PDMS surface was fabricated using a femtosecond laser to adhere to liquid metal circuits selectively. A trapezoidal hierarchical micro/nanostructure was fabricated as the surface of PDMS was ablated by laser irradiation at a distance of 30 μm. As a result, the roughness of the surface increases, and the liquid metal adheres easily to the non-laser-treated area, but the liquid metal does not adhere to the laser-treated area. This method made various high-resolution liquid metal patterns with a line width of at least 40 μm. This method is fast, simple, inexpensive, does not require additional vacuum equipment, and is expected to be highly applicable, such as fabricating wearable devices, soft electronics.