A Self-Supporting, Conductor-Exposing, Stretchable, Ultrathin, and Recyclable Kirigami-Structured Liquid Metal Paper for Multifunctional E-Skin

Electronic skin (E-skin) is a crucial seamless human-machine interface (HMI), holding promise in healthcare monitoring and personal electronics. Liquid metal (LM) has been recognized as an ideal electrode material to fabricate E-skins. However, conventional sealed LM electrodes cannot expose the LM layer for direct contact with the skin resulting in the low performance of electrophysiological monitoring. Furthermore, traditional printed LM electrodes are dif f icult to transfer or recycle, and fractures easily occur under stretching of the substrate. Here, we report a kind of LM electrode that we call a kirigami-structured LM paper (KLP), which is self-supporting, conductor-exposing, stretchable, ultrathin, and recyclable for multifunctional E-skin. The KLP is fabricated by the kirigami paper cutting art with three types of structures including uniaxial, biaxial, and square spiral. The KLP can act as an E-skin to acquire high-quality electrophysiological signals, such as electroencephalogram (EEG), electrocardiogram (ECG), and electromyogram (EMG). Upon integration with a triboelectric nanogenerator (TENG), the KLP can also operate as a self- powered E-skin. On the basis of the self-powered E-skin, we further developed a smart dialing communication system, which is applied on human skin to call a cellphone. Compared with conventional sealed or printed LM electrodes, the KLP can simultaneously achieve self-supporting, conductor-exposing, stretchable, ultrathin, and recyclable features. Such KLP offers potential for E-skins in healthcare monitoring and intelligent control, as well as smart robots, virtual reality, on-skin personal electronics, etc.

Automated summary

This article introduces a kind of liquid metal electrode called kirigami-structured LM paper (KLP), which is self-supporting, conductor-exposing, stretchable, ultrathin, and recyclable for multifunctional E-skin. The KLP can acquire high-quality electrophysiological signals and can operate as a self-powered E-skin when integrated with a triboelectric nanogenerator. The authors also developed a smart dialing communication system using the KLP on human skin to call a cellphone.