Compression-Durable Soft Electronic Circuits Enabled by Embedding Self-Healing Biphasic Liquid-Solid Metal Into Microstructured Elastomeric Channels.

Compression strongly degrades the electrical conductivity of the liquid-metal-based circuits because the liquid state is prone to be squashed. Here, a new compressible and stretchable biphasic liquid-solid self-healing circuit is proposed by filling GalnSn-BilnSn biphasic metal into micropillar-embedded channels. The underlying BilnSn solid alloy layer serves as a compression resistance layer, while the upper GalnSn liquid metal layer enables the real-time filling of the cracks in the solid layer under large deformations, resulting in autonomous self-healing and maintenance of conductivity under both stretching and compression. The embedded micropillars further improved the compression durability by providing additional mechanical support. The synergistic effect between the biphasic materials and embedded micropillar enables the designed stretchable conductor to show stable performance (R/R<10) under pressure of 38.2 MPa (≈389.5 Kgf cm) and cyclic pressure of 15.8 MPa over 7000 cycles (R/R<0.48%) without compromising the stretchability, whereas the liquid metal-based conductor can only endure pressure up to 2.5 MPa (25.49 Kgf cm). The stretchable antenna and hybrid circuits fabricated using the designed biphasic metal conductor showed enhanced compression durability. The structure-confined filling strategy enabled high-resolution and scalable manufacturing. Overall, robust stability under compression significantly expands the range of possible applications of liquid-metal-based conductors in soft electronics.