Fully Self-Powered Electrospray System via Triboelectric High Voltage Generator and Its Use to Control Wettability of Various Surfaces

Electrospray ionization (ESI) process, which is one of the most widely utilized techniques to produce micro/nanoscale and uniform particles, has become an important tool in various fields owing to its advantages. However, the electrospray process has been considered to have a low degree of freedom for portability because this process conventionally requires an external power supply to high-voltage generation, which is bulky and heavy hardware. To improve the versatility and applicable area of the electrospray process, the stationary power supply with required external wiring, should be replaced in the self-powered high voltage generator. Herein, we report a fully self-powered portable electrospray system (SPES) with the high-voltage generator based on the triboelectric generator (TEG) equipped with the voltage multiplier circuit (VMC), which does not require any fixed external equipment, thereby enabling the facile spraying of droplets without spatio-temporal limitation. TEG generates an alternating voltage of up to 1.5 kV that does not suitable form to perform the electrospray process. Thus, VMC is used to boost voltage and rectify alternating voltage into direct voltage, which is suitable for the process. The integration of both the TEG and the VMC can generate several kilovolts (i.e., 6.0–8.0 kV), which is sufficiently high for this process, by harvesting biomechanical energy. Moreover, the adoption of the ring-shaped electrode in SPES enables us to conduct the electrospray process regardless of the type of substrate. As a proof-of-concept demonstration, SPES has a great versatility not only to control wettability on any substrates but also to coat the micro/nanoscale particles on the surface of the materials in applications that required portability without external power sources, such as agriculture and air sterilization technology.