Thermomagnetic liquid metal switches with fast bidirectional response

Traditional thermal switches usually suffer from long-time and unidirectional response. Herein, we combined liquid metals with magnetic Ni₂Mn_1.4In_0.6 particles and developed a thermomagnetic liquid metal. These materials not only show excellent fluidity and electrical conductivity, but also exhibit fast response at a tuneable temperature that traditional magnetic liquid metals do not have. The ultimate application is designed as micro-channel thermal switch. Particularly, our thermal switch features bidirectional response through the droplet displacement, thus simultaneously cutting off the working circuit while turning on the fire extinguishing. Its response time of 1.2 s is 3.3 - 5.6 times faster than typical commercial thermal switches under the same hot source temperature of 75 °C, and it can be further reduced to 660 ms under the optimal environment. Moreover, this fast-response thermal switch offers the fastest recovery time, low cost, and long-cycle stability, showing a huge potential as a generation of thermal switches for diverse applications.