A tunable liquid metal electronic oscillator as a DC–AC converter

Liquid metals have unique qualities for developing new generation soft functional devices. Here, we propose that the oscillation of liquid metals induced by a DC voltage could be employed to make a frequency response electronic system, which differs in principle from conventional rigid devices. A novel resonance phenomenon in which stimulating an LM droplet with a DC voltage in a particular structure would exhibit a similar electrically ignited beating heart effect is discovered. Moreover, a tunable liquid metal electronic oscillator is demonstrated based on the resonance of the liquid metal droplet, which can directly transform the DC voltage into an AC signal without complex auxiliary components. The fabricated liquid metal electronic oscillator is constructed to produce a square wave with an oscillation frequency range spanning from 20 to 80 Hz under different droplet masses. Besides, the duty ratio of the signal generated by the liquid metal electronic oscillator can be conveniently regulated in the range of 25-70% while the frequency remains relatively stable. This work suggests a new type of field-controlled liquid metal droplet resonance in the field of signal generators that can be applied to future soft robotics, smart digital microfluidics, and more intelligent systems.