Nano-thick freestanding and reusable epidermal electronics via edge-supporting strategy.

Abstract

Nano-thick epidermal electronics have extraordinary lightweight and conformability characteristics, thus enable high-quality signal acquisition and imperceptible wearing experience. However, reducing the device thickness to nanoscale makes the rigidity extremely low thus the device curls spontaneously, imposing unprecedented challenges to the device fabrication, handling and recycling. To resolve the dilemma of epidermal electronics, we propose an edge-supporting strategy that maintains the benefits of nano thickness, meanwhile obtains practicality and reusability via reinforced edge scaffold. The nano-thick (~500 nm thick) core area of the device provides perfect conformal, firm, and burdenless contact with human skin. On the other hand, the edge scaffold (~5 μm thick) plays an important role in protecting internal fragile film from external forces and providing rigid support during handling and recycling. In addition, the edge scaffold enables spontaneous release of nano-thick electronics from the substrate in water, getting rid of the use of sacrificial layers and etchants. We demonstrate the use of the edge-supporting strategy to develop a physiological electrode with low impedance less than 3.6 kΩ at 1 kHz, a resistance-type temperature sensor with fast response time less than 0.5 ms and a nanoengineering-based pressure sensor with high sensitivity of 62.9 kPa^-1. Our work provides an effective method to handle and release nano-thick electronics without using external stamps, thereby enabling truly practical applications of ultrathin flexible electronics in the fields of wearable technology, healthcare and so on.