Multilevel Microstructured Flexible Pressure Sensors with Ultrahigh Sensitivity and Ultrawide Pressure Range for Versatile Electronic Skins

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 15; no. 10; pp. e1804559 - n/a
• Main Authors: Tang, Xing, Wu, Congyi, Gan, Lin, Zhang, Tian, Zhou, Tingting, Huang, Jin, Wang, Hao, Xie, Changsheng, Zeng, Dawen
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.03.2019
• Subjects: Contact pressure; Graphene; Health care; Heart rate; Multilevel; multilevel structure; Nanotechnology; Plantar pressure; Polydimethylsiloxane; pressure range; Pressure sensors; Prostheses; Robotics; Sandpaper; sandpapers; Sensitivity; Sensors; Wrist; pressure range; multilevel structure; sandpapers; graphene; pressure sensors
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.201804559

Flexible pressure sensors as electronic skins have attracted wide attention to their potential applications for healthcare and intelligent robotics. However, the tradeoff between their sensitivity and pressure range restricts their practical applications in various healthcare fields. Herein, a cost‐effective flexible pressure sensor with an ultrahigh sensitivity over an ultrawide pressure‐range is developed by combining a sandpaper‐molded multilevel microstructured polydimethylsiloxane and a reduced oxide graphene film. The unique multilevel microstructure via a two‐step sandpaper‐molding method leads to an ultrahigh sensitivity (2.5–1051 kPa−1) and can detect subtle and large pressure over an ultrawide range (0.01–400 kPa), which covers the overall pressure regime in daily life. Sharp increases in the contact area and additional contact sites caused by the multilevel microstructures jointly contribute to such unprecedented performance, which is confirmed by in situ observation of the gap variations and the contact states of the sensor under different pressures. Examples of the flexible pressure sensors are shown in potential applications involving the detection of various human physiological signals, such as breathing rate, vocal‐cord vibration, heart rate, wrist pulse, and foot plantar pressure. Another object manipulation application is also demonstrated, where the material shows its great potential as electronic skin intelligent robotics and prosthetic limbs. Compared with other microstructured flexible pressure sensors, this unique multilevel microstructure fabricated via a two‐step sandpaper‐molding method exhibits ultrahigh sensitivity and can detect subtle and large pressure over an ultrawide testing range, which can cover the entire expected pressure regime for practical applications. This sensor is promising for applications in wearable electronics and human health monitoring.