Abstract

Electrowetting-on-dielectric (EWOD) phenomenon is widely employed for liquid actuation at the micro scale. Due to its simple structure, low cost, low power consumption and fast response speed, diverse applications are developed and commercialized based on EWOD, such as digital microfluidics, tunable lenses, electronic displays, small-scale propellers etc. However, the liquid actuation with EWOD requires a high-voltage but low-current power source. The accessory equipment (e.g., waveform generator and amplifier) not only attenuates the benefits originated from microscale liquid actuation, but also limits its portability, wearability, and environmental friendliness of the EWOD inspired applications. Triboelectric nanogenerator (TENG) is a promising technology to convert arbitrary mechanical energy to electricity based on triboelectrification and electrostatic induction. The output electric signal shows a high-voltage but low-current property which well matches the demands in EWOD devices. This paper reviews the technical advances in the TENG powered EWOD devices developed in recent years. The mechanisms, structures, and performance of each application are reviewed. The challenges and future perspectives are put forward. The review and discussion in this study open up opportunities for the development of TENG and EWOD based self-powered liquid actuators.