Laser Micromachining of Liquid Metal Patterns for Stretchable Electronic Circuits

Stretchable electronic circuits are crucial for wearable computing, soft robotics, and bio-integrated devices. Gallium-based liquid metal (LM) conductors offer exceptional electrical and mechanical properties, yet they are difficult to pattern due to their high surface tension and weak adhesion to several surfaces. Here, we introduce a rapid (<3 h), cost-effective (~;$15/device) fabrication approach that combines UV-laser micromachining with a facile copper foil wetting layer to enable high-resolution patterning of LM circuits on diverse substrates, including elastomers, fabrics, and adhesives. This cleanroom-free process achieves high resolution (60 μm) and improved electrical interfacing through hydrochloric acid vapor treatment. The resulting circuits maintain functionality under high strain (>100%) and cyclic loading. To demonstrate the fabrication approach, a wearable pulse oximeter is created for real-time monitoring of heart rate. This scalable and maskless fabrication approach broadens the accessibility of stretchable LM-based electronics by reducing production costs and enabling rapid prototyping for next-generation wearable and soft robotic systems.