Multi-Substrate Liquid Metal Circuits Printing via Superhydrophobic Coating and Adhesive Patterning

Printed circuits and electronics are widely implemented in a variety of emerging areas including solar power panel, wearable devices, screen display, etc. Recently, gallium-based alloys become promising candidates in applications ranging from flexible electronics to efficient cooling due to its high conductivity, fluidity, and nontoxicity. However, the implementation of liquid metal printing is highly restricted to its adhesion with different substrates. The adhesiveness can be enhanced by promoting the oxidation such as intensive stirring, whereas the fluidity would be severely confined. Aiming to tackle the existing challenges, here the authors propose a facile liquid metal printed electronics method through spraying a customized superhydrophobic film upon the substrate and then forming desired patterns via selective adhesion of liquid metal. The required customization can be realized via removable mask or surface energy variation. The presented strategy demonstrates excellent substrate adaptability including glass, plastic, paper, carbon fiber composite, ceramic, etc. Besides, complex 3D circuits can be created upon curved surfaces of diversified geometries. Sprayed liquid metal can be easily recycled, which is beneficial to an environmental and sustainable production. This work suggests a potential direction for liquid metal circuit fabrication and may enlighten other studies to resolve liquid metal contamination, flow friction, etc.