Gallium-based liquid metal can be used as a material for microheaters because it can be easily filled into microchannels and electrified to generate Joule heat, but the liquid metal-based microheater will suffer breakage induced by voids forming within the liquid metal when the temperature normally gets higher than 100 °C. To resolve this problem, a novel liquid metal-based microheater with parallel ventilating side-channels is presented. It consists of a liquid-metal heating channel and two parallel ventilating side-channels. The heating channel is connected with the side-channels by small gaps between polydimethylsiloxane (PDMS) posts. Experimental results show that this novel microheater can be heated up to 200 °C without damage. To explain its excellent performance, an experiment is performed to discover the development of the voids within the liquid-metal heating channel, and two reasons are put forward in this work on the basis of the experiment. Afterward pressing and bending tests are conducted to explore the mechanical stability of the novel microheaters. Finally, the microheaters are applied to warm water to show their good flexibility on non-flat surfaces. In consequence, the novel liquid metal-based microheater is believed to be widely applicable to soft micro-electro-mechanical system(MEMS) heating devices.
Keywords: liquid metal-based microheaters; trapped air; ventilating side-channels; voids.