Resonant droplet jumping under pulsed electric fields

Droplet removal from open surfaces plays a vital role in various cutting-edge applications. Droplet jumping is an efficient and controllable strategy for liquid removal, and it requires sufficient mechanical energy to overcome surface adhesion and gravity. However, generating sufficient mechanical energy usually requires strong external stimuli, which complicates the actuation process and hinders practical operation. To address this challenge, we develop a resonant strategy for electrically driven droplet jumping using pulsed electric fields. Unlike the quasi-static, elongated shapes observed under constant electric fields, droplets oscillate under pulsed electric fields induced by periodically varying Maxwell stresses. Periodic electrical work is injected into the droplet during each pulse, allowing mechanical energy to accumulate progressively until the jumping threshold is reached. The threshold is highly dependent on the pulse frequency and the droplet size. Based on the Maxwell stress analysis together with a scaling analysis, we establish a scaling relation between pulse parameters and droplet volume. Through synergistic coupling of resonant frequency matching and electric field direction control, we achieve directed transport and precise sorting of droplets with different volumes. This work provides a new pathway for low-energy, high-precision droplet jumping on open surfaces, with promising applications in microfluidic sorting, enhanced heat transfer, and anti-icing technologies.