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

Abstract

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.

Breathable Electronic Skins for Daily Physiological Signal Monitoring

“…6 a). Besides, in daily long-term wearing applications, the interference of human daily activities and the external environment to the monitored signals should be fully considered in the design of multifunctional e-skin [ 95 ] (Fig. 6 b).…”

Emerging Liquid Metal Biomaterials: From Design to Application

“…[ 108,109 ] Generally, active materials in biosensors can collect biophysical or biochemical signals and convert them into measurable signals. [ 110 ] The input signals could be stress, [ 73,111,112 ] strain, [ 46,104,113–116 ] pressure, [ 98,117–120 ] temperature, [ 121,122 ] electrophysiology, [ 123–125 ] chemistry, [ 59,126–128 ] and so on. While the output signals are usually electrical, such as electricity, resistance, and capacitances.…”

Laser-Patterned Hierarchical Aligned Micro-/Nanowire Network for Highly Sensitive Multidimensional Strain Sensor

“…Wearable strain sensors monitoring electrical signals stimulated by mechanical motions have received tremendous attention in fields such as soft robotics, − motion monitoring, − and electronic skin − over the past decade. The sensing mechanisms of strain sensors include piezoelectricity, capacitance, piezoresistivity, and triboelectricity. − Piezoresistive-type strain sensors based on external strain-induced electrical resistance response have been widely used due to the merits of simple construction, facile measurement, and high sensitivity. , However, most of the existing strain sensors can merely detect uniaxial strain owing to the coupled strain responses between the parallel and perpendicular directions of applied loadings, limiting the accurate detection of complicated human movements, including direction and amplitude in real time. − …”