Skin-Inspired Hair-Epidermis-Dermis Hierarchical Structures for Electronic Skin Sensors with High Sensitivity over a Wide Linear Range.

Abstract

The quest for both high sensitivity and a wide linear range in electronic skin design is perpetual; unfortunately, these two key parameters are generally mutually exclusive. Although limited success in attaining both high sensitivity and a wide linear range has been achieved <i>via</i> material-specific or complicated structure design, addressing the conflict between these parameters remains a critical challenge. Here, inspired by the human somatosensory system, we propose hair-epidermis-dermis hierarchical structures based on a reduced graphene oxide/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) aerogel to reconcile this contradiction between high sensitivity and a wide linear range. This hierarchical structure enables an electronic skin (e-skin) sensor linear sensing range up to 30 kPa without sacrificing the high sensitivity (137.7 kPa^-1), revealing an effective strategy to overcome the above-mentioned conflict. In addition, the e-skin sensor also exhibits a low detection limit (1.1 Pa), fast responsiveness (∼80 ms), and excellent stability and reproducibility (over 10 000 cycles); as a result, the e-skin platform is capable of detecting small air flow and monitoring human pulse and even sound-induced vibrations. This structure may boost the ongoing research on the structural design and performance regulation of emerging flexible electronics.