# Liquid-liquid triboelectric nanogenerator based on the immiscible interface of an aqueous two-phase system

## TL;DR

A new liquid-liquid nanogenerator uses an immiscible aqueous interface to improve charge transfer and could be used in implantable devices.

## Contribution

A liquid-liquid triboelectric nanogenerator is designed using an immiscible aqueous-aqueous interface to achieve stable charge transfer.

## Key findings

- The nanogenerator achieves a contact surface charge transfer of 129 nC per droplet.
- The design is applicable in humid environments and shows good biocompatibility.
- The system can function as an effective drug carrier and supports aqueous electronics.

## Abstract

Solid nanogenerators often have limited charge transfer due to their low contact area. Liquid–liquid nanogenerators can transfer a charge better than the solid–solid and solid–liquid counterparts. However, the precise manipulation of the liquid morphology remains a challenge because of the fluidity limits of the liquid. In this work, using the surface tension of a droplet to fix its shape, a liquid-liquid triboelectric nanogenerator in Contact-Separation mode is designed using an immiscible aqueous-aqueous interface, achieving a contact surface charge transfer of 129 nC for a single droplet. The configuration is proven to be applicable in humid environments, and the two-phase materials have good biocompatibility and can be used as an effective drug carrier. Therefore, this nanogenerator is useful for designing future implantable devices. Meanwhile, this design also establishes the foundation of aqueous electronics, and additional applications can be achieved using this route.

While liquid-liquid interface offers better contact and charge transfer potential than solid-based counterparts, fluidity still poses challenges for their application. Here, authors show that charge transfer exists in aqueous two-phase systems and propose a nanogenerator design based on the immiscible aqueous-aqueous interface.