Stretchable electronic skin based on silver nanowire composite fiber electrodes for sensing pressure, proximity, and multidirectional strain

Abstract

Electronic skin (E-skin) has been attracting great research interest and effort due to its potential applications in wearable health monitoring, smart prosthetics, robot skins and so on. To expand its applications, two key challenges lie in the realization of device stretchability, and independent sensing of pressure and multidirectional lateral strain. Here we made a combination of rational device structure and artfully engineered sensing materials to fulfill the mentioned demands. The as-prepared E-skin took a simple orthogonal configuration to enable both capacitive mode for pressure sensing and resistive mode for multidirectional strain sensing, independently. Pre-cracked silver nanowire based fibers with helical microstructures were utilized as basic electrodes to endow the E-skin with intrinsic stretchability and strain sensing capability. Through dielectric layer optimization, the pressure sensing sensitivity was greatly enhanced, with a detection limit of 1.5 Pa. For application demonstrations, we utilized the E-skin as both flat and curved platforms for pressure mapping, and also as human motion sensors, such as palm and thumb bending.

Surface coatings of silver nanowires lead to effective, high conductivity, high-strain, ultrathin sensors

“…. As an alternative material, silver nanowires (AgNWs) have been of great interest [25][26][27][28][29][30][31][32][33][34][35][36][37][38] due to the ability to form highly conductive percolative networks. [38][39][40][41] AgNW based sensing composite materials, formed exclusively by layer deposition, consist of a percolative network of the nanowires adhered to a flexible polymer substrate.…”

Strategies for Designing Stretchable Strain Sensors and Conductors

“…To address this issue, many efforts have been devoted to the development of anisotropic sensors . One strategy is to make the sensors into an orthogonal structure .…”

Smart Sensing Systems Using Wearable Optoelectronics

“…In addition, the ability to provide thermally applicable processing at higher temperatures than any glass transition or melting temperatures, along with large‐area compatibility, has garnered tremendous interest for application in wearable optoelectronic sensors. Several conventional candidates are available, such as polyimide (PI), polyethylene terephthalate (PET) as plastic materials, and silicone rubber matrices like Ecoflex and poly‐dimethylsiloxane (PDMS) with a low Young's modulus. In addition to choosing soft materials with a low Young's modulus, another active area is in atomic scale or ultrathin underlying substrates, such as Cu or Al foils and glasses .…”