Highly sensitive, self-powered and wearable electronic skin based on pressure-sensitive nanofiber woven fabric sensor

Abstract

The wearable electronic skin with high sensitivity and self-power has shown increasing prospects for applications such as human health monitoring, robotic skin, and intelligent electronic products. In this work, we introduced and demonstrated a design of highly sensitive, self-powered, and wearable electronic skin based on a pressure-sensitive nanofiber woven fabric sensor fabricated by weaving PVDF electrospun yarns of nanofibers coated with PEDOT. Particularly, the nanofiber woven fabric sensor with multi-leveled hierarchical structure, which significantly induced the change in contact area under ultra-low load, showed combined superiority of high sensitivity (18.376 kPa^-1, at ~100 Pa), wide pressure range (0.002-10 kPa), fast response time (15 ms) and better durability (7500 cycles). More importantly, an open-circuit voltage signal of the PPNWF pressure sensor was obtained through applying periodic pressure of 10 kPa, and the output open-circuit voltage exhibited a distinct switching behavior to the applied pressure, indicating the wearable nanofiber woven fabric sensor could be self-powered under an applied pressure. Furthermore, we demonstrated the potential application of this wearable nanofiber woven fabric sensor in electronic skin for health monitoring, human motion detection, and muscle tremor detection.

Figure 1

(a) Schematic illustrations for preparation of PEDOT@PVDF nanofiber woven fabric; (b) optical image of PEDOT@PVDF nanofiber fabric; SEM images of PEDOT@FVDF (c) nanofiber fabric, (d) nanofiber yarn, (e) oriented nanofibers, and (f) single nanofiber.

Figure 2

(a) TEM image of PEDOT@PVDF nanofiber; (b) mapping image of the S element in PEDOT; XPS results of (c) wide-scan spectrum of PVDF and PEDOT@PVDF nanofiber yarn and (d) S2p spectrum of PEDOT in PEDOT@PVDF nanofiber yarn.

Figure 3

(a) I-V curves of PPNWF pressure sensor and (b) initial current under different pressures; (c) open-circuit voltage signal of PPNWF pressure sensor under an applied periodic pressure of 10 kPa; (d) voltage signal of PPNWF pressure sensor under different pressures.

Figure 4

(a) Relative change in current versus applied pressure; (b) Static current response under varying pressure; (c) Dynamic instantaneous current response to varying pressure; (d) Schematic diagram of the main structural change in the PPNWF pressure sensor during the compression process; (e) Response to applied pressure with various frequencies; (f) a typical signal of current change at 25 Hz in (e); (g) Durability recorded by repeated loading-unloading cycles at a frequency of 25 Hz and a pressure of 10 kPa.

Figure 5

Application of PPNWF pressure sensor. (a) current response to ultra-light objects; (b,c) monitoring of muscle movement on human face; (d–f) monitoring of voice when people sang; (g–i) current change according to wrist pulse before and after exercise.