Highly efficient liquid droplet manipulation via human-motion-induced direct charge injection

A highly efficient droplet manipulation system was developed using human motions induced direct charge injection. It is able to inject 0.25 nC of charge into the droplet achieving an average velocity of 255 mm s −1 , which is 6 times higher than that using the conventional mechanism. The current electrowetting mechanisms show a low efficiency, although manipulating liquid droplets is essential to biological and chemical fields. Herein, we propose a highly efficient droplet manipulating method using direct charge injection (DCI) via human motion induced triboelectricity. A triboelectric nanogenerator (TENG) is used to provide both the charges and strong electric fields to drive the movement of liquid droplets. Using this method, the charge quantity and average velocity of the droplet (10 μL) reach 0.25 nC and 255 mm s −1 , respectively, over 6 times higher than those of traditional methods (0.03 nC and 43.2 mm s −1 ). Alternative charge injection was demonstrated to enable both reciprocating and jumping motions of the droplet. Finally, we also successfully devised and demonstrated a platform with versatile system-level functions including droplets transportation, positioning, merging, and cleaning. This work advances the current droplet manipulation field via introducing a compelling approach using human-motion-induced direct charge injection.