Advancing the pressure sensing performance of conductive CNT/PDMS composite film by constructing a hierarchical-structured surface
Ye Zhao, Taoyu Shen, Minyue Zhang, Rui Yin, Yanjun Zheng, Hu Liu, Hongling Sun, Chuntai Liu, Changyu Shen
Abstract
Flexible pressure sensors have attracted wide attention due to their applications to electronic skin, health monitoring, and human-machine interaction. However, the tradeoff between their high sensitivity and wide response range remains a challenge. Inspired by human skin, we select commercial silicon carbide sandpaper as a template to fabricate carbon nanotube (CNT)/polydimethylsiloxane (PDMS) composite film with a hierarchical structured surface (h-CNT/PDMS) through solution blending and blade coating and then assemble the h-CNT/PDMS composite film with interdigitated electrodes and polyurethane (PU) scotch tape to obtain an h-CNT/PDMS-based flexible pressure sensor. Based on in-situ optical images and finite element analysis, the significant compressive contact effect between the hierarchical structured surface of h-CNT/PDMS and the interdigitated electrode leads to enhanced pressure sensitivity and a wider response range (0.1661 kPa−1, 0.4574 kPa−1 and 0.0989 kPa−1 in the pressure range of 0–18 kPa, 18–133 kPa and 133–300 kPa) compared with planar CNT/PDMS composite film (0.0066 kPa−1 in the pressure range of 0–240 kPa). The prepared pressure sensor displays rapid response/recovery time, excellent stability, durability, and stable response to different loading modes (bending and torsion). In addition, our pressure sensor can be utilized to accurately monitor and discriminate various stimuli ranging from human motions to pressure magnitude and spatial distribution. This study supplies important guidance for the fabrication of flexible pressure sensors with superior sensing performance in next-generation wearable electronic devices.