Microscale Liquid Metal Conductors for Stretchable and Transparent Electronics

Integrated wearable electronics capable of transducing and transmitting biophysical information on complex and dynamic systems are attracting high interest across the consumer electronics, clinical, and research domains. Gallium and gallium-based liquid metals (LMs) emerge as promising conductor technology for wearables due to their excellent combination of electrical conductivity and mechanical compliance. However, LMs feature complex physical and chemical properties that pose significant manufacturability challenges. Herein, a microtechnology approach is presented to fabricate deformable, microscale LM conductors with high surface density and over large surface areas. Based on a combination of soft lithography, directional patterning, and thermal evaporation of gallium, this new technology enables a range of designs and geometries that can be used to form LM-based stretchable electronic conductors. The versatility of the technology enables a palette of circuit designs that can offer unrivaled transparency (T > 89%) or large metallization density (2/5 µm line/gap).