Cost-Effective Fabrication of Transparent Strain Sensors via Micro-Scale 3D Printing and Imprinting.

Rui Wang,Hongbo Lan,Wensong Ge,Luanfa Sun,Xiaoyang Zhu,Hongke Li,Shuai Shang

doi:10.3390/nano12010120

Abstract

The development of strain sensors with high sensitivity and stretchability is essential for health monitoring, electronic skin, wearable devices, and human-computer interactions. However, sensors that combine high sensitivity and ultra-wide detection generally require complex preparation processes. Here, a novel flexible strain sensor with high sensitivity and transparency was proposed by filling a multiwalled carbon nanotube (MWCNT) solution into polydimethylsiloxane (PDMS) channel films fabricated via an electric field-driven (EFD) 3D printing and molding hybrid process. The fabricated flexible strain sensor with embedded MWCNT networks had superior gauge factors of 90, 285, and 1500 at strains of 6.6%, 14%, and 20%, respectively. In addition, the flexible strain sensors with an optical transparency of 84% offered good stability and durability with no significant change in resistance after 8000 stretch-release cycles. Finally, the fabricated flexible strain sensors with embedded MWCNT networks showed good practical performance and could be attached to the skin to monitor various human movements such as wrist flexion, finger flexion, neck flexion, blinking activity, food swallowing, and facial expression recognition. These are good application strategies for wearable devices and health monitoring.

Highlights

Flexible strain sensors play an important role in applications such as health monitoring [1,2,3], electronic skin [4,5,6], wearable devices [7,8,9,10,11,12], and human-computer interactions [13]
The results show that multiwalled carbon nanotube (MWCNT) is well-filled at the 10:1 ratio with no obvious cracks in the channel; the MWCNT exhibits few cracks at the 15:1 ratio, and the MWCNT is less filled at the 20:1 ratio with more obvious cracks in the channel
The ratio of PDMS has a strong influence on the interfacial stability of the conductive structures; the stability of the channel network improves as the PDMS ratio increases, effectively filling the MWCNT into the channel as the blade cuts across the channel surface

Summary

Introduction

Flexible strain sensors play an important role in applications such as health monitoring [1,2,3], electronic skin [4,5,6], wearable devices [7,8,9,10,11,12], and human-computer interactions [13]. Sensitivity and tensile properties are two important parameters for evaluating the performance of sensors [14,15]. Parameters such as response time and dynamic stability are crucial for their practical applications. Most strain sensors are opaque to ensure sensitivity and tensile properties, which limits their practical application in areas such as the face, neck, and other visible areas

Methods

Results

Conclusion