A 3D-printed stretchable strain sensor for wind sensing

• Published in: Smart materials and structures Vol. 28; no. 8; pp. 84001 - 84009
• Main Authors: Al-Rubaiai, Mohammed, Tsuruta, Ryohei, Gandhi, Umesh, Wang, Chuan, Tan, Xiaobo
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.08.2019
• Subjects: 3D-printing; finite-element modeling; flow sensing; strain gauge
• ISSN: 0964-1726; 1361-665X
• DOI: 10.1088/1361-665X/ab1fa9

Stretchable strain sensors with large strain range, high sensitivity, and excellent reliability are of great interest to applications in soft robotics, wearable devices, and structure-monitoring systems. Unlike conventional template lithography-based approaches, 3D-printing can be used to fabricate complex devices in a simple and cost-effective manner. In this paper, we report 3D-printed stretchable strain sensors that embed a flexible conductive composite material in a hyper-elastic substrate. Three commercially available conductive filaments are explored, among which the ETPU from Rubber3D Printing, Sweden, shows the highest sensitivity (gauge factor of 20), with a working strain range of 0%-12.5%. The ETPU strain sensor exhibits an interesting behavior where the conductivity increases with the strain. In addition, the resistance change of the ETPU sensor in a doubly-clamped configuration in response to a wind stimulus is characterized, and the sensor shows sensitivity to wind velocity beyond 3.5 m s−1. The experimentally identified material parameters are used in finite-element modeling and simulation to investigate the behavior of the 3D-printed stretchable strain sensor when subjected to wind loading. In particular, the model-predicted sensor output at different wind speeds, obtained with the computed sensor strain and the experimentally characterized strain-resistance relationship, achieves good match with the experimental data.