Fast and Facile Liquid Metal Printing via Projection Lithography for Highly Stretchable Electronic Circuits

Soft electronic circuits are crucial for wearable electronics, biomedical technologies, and soft robotics, requiring soft conductive materials with high conductivity, high strain limit, and stable electrical performance under deformation. Liquid metals (LMs) have become attractive candidates with high conductivity and fluidic compliance, while effective manufacturing methods are demanded. Digital light processing (DLP)-based projection lithography is a high-resolution and high-throughput printing technique for primarily polymers and some metals. If LMs can be printed with DLP as well, the entire soft devices can be fabricated by one printer in a streamlined and highly efficient process. Herein, fast and facile DLP-based LM printing is achieved. Simply with 5-10 s of patterned ultraviolet (UV)-light exposure, a highly conductive and stretchable pattern can be printed using a photo-crosslinkable LM particle ink. The printed eutectic gallium indium traces feature high resolution (≈20 µm), conductivity (3 × 10