Weichart Johannes, Sivananthaguru Pragash, Coulter Fergal B, Burger Thomas, Hierold Christofer
Micro and Nanosystems Group, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland.
Integrated Systems Laboratory, Department of Information Technology and Electrical Engineering, ETH Zurich, Zurich, Switzerland.
Soft Robot. 2024 Aug;11(4):573-584. doi: 10.1089/soro.2022.0238. Epub 2024 Apr 25.
Replication of the human sense of touch would be highly advantageous for robots or prostheses as it would allow an agile and dexterous interaction with the environment. The article presents an approach for the integration of a micro-electromechanical system sensing skin with 144 tactile sensors on a soft, human-sized artificial fingertip. The sensing technology consists of thin, 1D sensing strips which are wrapped around the soft and curved fingertip. The sensing strips include 0.5 mm diameter capacitive sensors which measure touch, vibrations, and strain at a resolution of 1 sensor/mm. The method allows to leverage the advantages of sensing skins over other tactile sensing technologies while showing a solution to integrate such skins on a soft three-dimensional body. The adaptable sensing characteristics are dominated by the thickness of a spray coated silicone layer, encapsulating the sensors in a sturdy material. We characterized the static and dynamic sensing capabilities of the encapsulated taxels up to skin thicknesses of 600 μm. Taxels with 600 μm skin layers have a sensitivity of 6 fF/mN, corresponding to an ∼5 times higher sensitivity than a human finger if combined with the developed electronics. They can detect vibrations in the full tested range of 0-600 Hz. The softness of a human finger was measured to build an artificial sensing finger of similar conformity. Miniaturized readout electronics allow the readout of the full finger with 220 Hz, which enables the observation of touch and slipping events on the artificial finger, as well as the estimation of the contact force. Slipping events can be observed as vibrations registered by single sensors, whereas the contact force can be extracted by averaging sensor array readouts. We verified the sturdiness of the sensing technology by testing single coated sensors on a chip, as well as the completely integrated sensing fingertip by applying 15 N for 10,000 times. Qualitative datasets show the response of the fingertip to the touch of various objects. The focus of this article is the development of the sensing hardware and the basic characterization of the sensing performance.
复制人类触觉对机器人或假肢将极为有利，因为这将使它们能够与环境进行灵活且灵巧的交互。本文介绍了一种将微机电系统传感皮肤与一个柔软的、与人手指大小相当的人造指尖上的144个触觉传感器集成的方法。传感技术由薄的一维传感条组成，这些传感条缠绕在柔软且弯曲的指尖上。传感条包含直径为0.5毫米的电容式传感器，可测量触摸、振动和应变，分辨率为每毫米1个传感器。该方法能够利用传感皮肤相对于其他触觉传感技术的优势，同时展示了将此类皮肤集成到柔软三维物体上的解决方案。可适应的传感特性主要由喷涂硅树脂层的厚度决定，该层将传感器封装在一种坚固的材料中。我们对封装后的像素在高达600微米的皮肤厚度下的静态和动态传感能力进行了表征。具有600微米皮肤层的像素灵敏度为6飞法/毫牛，如果与所开发的电子设备相结合，其灵敏度比人类手指高出约5倍。它们能够在0至600赫兹的整个测试范围内检测振动。测量了人类手指的柔软度，以构建具有相似贴合度的人造传感手指。小型化的读出电子设备允许以220赫兹的频率读出整个手指的信号，这使得能够观察人造手指上的触摸和滑动事件，以及估计接触力。滑动事件可作为单个传感器记录的振动来观察，而接触力可通过对传感器阵列读数求平均值来提取。我们通过在芯片上测试单个涂层传感器以及对完全集成的传感指尖施加15牛的力达10000次，验证了传感技术的坚固性。定性数据集展示了指尖对各种物体触摸的响应。本文的重点是传感硬件的开发以及传感性能的基本表征。
