Electric field-driven uniform droplet generation of liquid metal

Liquid metals have garnered widespread attention in the fields of electronics and materials science due to their unique combination of fluidity and electrical conductivity. Conventional liquid metal droplet generators typically rely on piezoelectric actuators to impose mechanical perturbations on the jet to control droplet formation. In this work, we present a new method for generating a uniform and controllable stream of liquid metal microdroplets by applying periodic electrostatic perturbations to the jet. Using a nozzle with an inner diameter of 25 $\upmu$m, we achieved continuous generation of droplets approximately 51 $\upmu$m in diameter at a frequency of 110 kHz. By adjusting the nozzle diameter, flow rate, and the frequency of the applied voltage, the size and spacing of the droplets can be effectively tuned. Moreover, a comparison between experimental observations and theoretical predictions under various conditions demonstrates that the Rayleigh-Plateau instability theory accurately describes the disturbance growth and droplet formation underelectric field excitation. Our study provides both theoretical and experimental foundations for the controlled generation of gallium-based liquid metal droplets.