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.

中文翻译：

---

用于两栖步态监测的一次性校准的柔性电容曲率传感器

使用柔性电子设备开发的可穿戴设备在人体健康监测和运动传感方面具有巨大的潜在应用。尽管材料柔软性和结构灵活性提供了可变形的人机界面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，因为它们通常需要在每次安装时进行校准。本文介绍了一种设计和制造柔性曲率传感器的方法，以测量用于两栖应用的人体关节运动。这种柔性传感器采用电容传感原理，其中介电层和电极由聚氨酯树脂和共晶镓铟 (EGaIn) 液态金属制成；制造工艺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光束模型，通过补偿无法预料的手动安装误差，使传感器在一次性校准后可重复使用。在两栖步态中脚踝传感的说明性应用表明，在跑步机测试中，不同步行速度（0.7-1.1 m/s）的均方根误差在 5° 以内，而对于准水下传感，最大误差在 3° 以内。 -静态测量。预计所提出的防水柔性传感器可以突破可穿戴机器人、人类运动及其相关应用的界限。在两栖步态中脚踝传感的说明性应用表明，在跑步机测试中，不同步行速度（0.7-1.1 m/s）的均方根误差在 5° 以内，而对于准水下传感，最大误差在 3° 以内。 -静态测量。预计所提出的防水柔性传感器可以突破可穿戴机器人、人类运动及其相关应用的界限。在两栖步态中脚踝传感的说明性应用表明，在跑步机测试中，不同步行速度（0.7-1.1 m/s）的均方根误差在 5° 以内，而对于准水下传感，最大误差在 3° 以内。 -静态测量。预计所提出的防水柔性传感器可以突破可穿戴机器人、人类运动及其相关应用的界限。