Versatile Electronic Skins for Motion Detection of Joints Enabled by Aligned Few-Walled Carbon Nanotubes in Flexible Polymer Composites

Here, novel multifunctional electronic skins (E-skins) based on aligned few-walled carbon nanotube (AFWCNT) polymer composites with a piezoresistive functioning mechanism different from the mostly investigated theory of “tunneling current channels” in randomly dispersed CNT polymer composites are demonstrated. The high performances of as-prepared E-skins originate from the anisotropic conductivity of AFWCNT array embedded in flexible composite and the distinct variation of “tube-to-tube” interfacial resistance responsive to bending or stretching. The polymer/AFWCNT-based flexion-sensitive E-skins exhibit high precision and linearity, together with low power consumption (<10 µW) and good stability (no degradation after 15 000 bending–unbending cycles). Moreover, polymer/AFWCNT composites can also be used for the construction of tensile-sensitive E-skins, which exhibit high sensitivity toward tensile force. The polymer/AFWCNT-based E-skins show remarkable performances when applied to monitor the motions and postures of body joints (such as fingers), a capability that can find wide applications in wearable human–machine communication interfaces, portable motion detectors, and bionic robots.