# A Stretchable Electronic Tattoo for Self-Powered Human–Machine Interfaces and Therapeutic Applications

## TL;DR

A stretchable electronic tattoo is developed for self-powered human-machine interfaces and drug delivery, using graphene-gold conductors that remain stable under strain.

## Contribution

The paper introduces a dual-conductive pathway and kirigami structure in graphene-gold film to enable stable, stretchable electronic tattoos.

## Key findings

- The graphene–gold conductors maintain stable resistance under mechanical deformation due to a dual conductive pathway and folding structure.
- Kirigami-structured film conductors achieve high conductivity and negligible resistance changes over a strain range of 0 to 130%.
- The developed on-skin patches enable waterproof drug delivery and a self-powered dialing interface using triboelectric nanogenerators.

## Abstract

Flexible skin electronics are increasingly sought after for their potential in sensing and drug delivery within wearable human–machine interfaces. However, developing multifunctional applications that maintain biocompatibility and stable electrical performance under various mechanical deformations remains a challenge. Here, we introduce tattoo paper-based graphene–gold conductors that are approximately 0.04 mm thick and feature a dual conductive pathway within the graphene–gold film. By integrating a folding structure with this dual conductive pathway, we can mitigate the strain effects on the electrical resistance of film-based conductors, resulting in wider areas of stable resistance. In addition, we have designed film conductors with a kirigami structure, which achieves a high initial conductivity of 1.5 × 103 S cm−1 and exhibits negligible resistance changes across a broad strain range of 0 to 130%. We utilize these conductors to develop waterproof on-skin patches that incorporate electrically and optically active heaters for body heating and drug delivery. Furthermore, we have created an on-skin dialing interface using these conductors, which enables users to make telephone calls based on triboelectric nanogenerators.