State Key Laboratory of Digital Manufacturing Equipment and Technology, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, China.
George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA.
Soft Robot. 2021 Apr;8(2):164-174. doi: 10.1089/soro.2019.0151. Epub 2020 May 26.
Wearable devices developed with flexible electronics have great potential applications for human health monitoring and motion sensing. Although material softness and structural flexibility provide a deformable human-machine interface to adapt to joint bending or tissue stretching/compression, flexible sensors are inconvenient in practical uses as they usually require calibration every time they are installed. This article presents an approach to design and fabricate a flexible curvature sensor to measure human articular movements for amphibious applications. This flexible sensor employs the capacitive sensing principle, where the dielectric layer and electrodes are made from the polyurethane resin and eutectic gallium-indium (EGaIn) liquid metal; and the fabrication process is implemented with shape deposition molding for batch production. The sensing method for articular rotation angles employs the Euler beam model to make the sensor reusable after one-time calibration by compensating for the unpredicted manual installation error. The illustrative application to ankle sensing in amphibious gaits shows that the root-mean-square error is within 5° for different walking speeds (0.7-1.1 m/s) in treadmill tests and the maximum error is within 3° for underwater sensing with quasi-static measurements. It is expected that the proposed waterproof flexible sensor can push the boundaries of wearable robotics, human locomotion, as well as their related applications.
可穿戴设备采用柔性电子技术开发，在人体健康监测和运动感应方面具有巨大的潜在应用。尽管材料柔软度和结构灵活性为可变形人机界面提供了适应性，以适应关节弯曲或组织拉伸/压缩，但柔性传感器在实际使用中并不方便，因为它们通常需要每次安装时进行校准。本文提出了一种设计和制造柔性曲率传感器的方法，用于测量两栖应用中的人体关节运动。该柔性传感器采用电容感应原理，介电层和电极由聚氨酯树脂和共晶镓-铟（EGaIn）液态金属制成；制造过程采用形状沉积成型进行批量生产。关节旋转角度的传感方法采用欧拉梁模型，通过补偿不可预测的手动安装误差，实现传感器的一次性校准后的可重复使用。在两栖步态的踝关节传感应用中，跑步机测试的不同步行速度（0.7-1.1m/s）下的均方根误差在 5°以内，准静态测量下水下传感的最大误差在 3°以内。预计提出的防水柔性传感器将推动可穿戴机器人、人类运动及其相关应用的发展。
