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 difficult 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.
