Power-Level Electrical Switch Enabled by a Liquid-Metal Bridge

Soft electronic components possess the potential to be developed into next-generation electrical devices that can provide superior performance to solid-state counterparts. Among commonly used components, electrical switches are an essential control element in electrical and electronic systems. Both solid-state mechanical and semiconductor switches are blamed for some intrinsic shortcomings. For example, the former suffers from contact surface degradation, while the latter functions with a high conduction loss. To overcome the limitations, here, a liquid metal (LM)-enabled electrical switch is reported by incorporating a Galinstan liquid bridge into a pair of solid electrodes. The electrical switch operation is realized by the coalescence of LM droplets and the breakup of the LM bridge. Extraordinarily, the device is capable of interrupting a DC 220 V, 1-5 A circuit within 11 ms, outperforming a common mechanical switch by a factor of 4-20 in terms of interruption speed. During the breakup process of an LM bridge in the presence of a current, three regimes characterized by electrical arc behaviors are identified and investigated. The rupture distance formed before pinch-off is critical to regulate the arc plasma behaviors. The presented applications and discoveries have a vast potential in both practical technologies, involving high-current electrical and electronic equipment, and fundamental research fields relevant to soft electronics, fluid mechanics, and plasma science.