Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY 14853.
Faculty of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa 3200003, Israel.
Proc Natl Acad Sci U S A. 2021 Sep 28;118(39). doi: 10.1073/pnas.2106553118.
Existing tactile stimulation technologies powered by small actuators offer low-resolution stimuli compared to the enormous mechanoreceptor density of human skin. Arrays of soft pneumatic actuators initially show promise as small-resolution (1- to 3-mm diameter), highly conformable tactile display strategies yet ultimately fail because of their need for valves bulkier than the actuators themselves. In this paper, we demonstrate an array of individually addressable, soft fluidic actuators that operate without electromechanical valves. We achieve this by using microscale combustion and localized thermal flame quenching. Precisely, liquid metal electrodes produce sparks to ignite fuel lean methane-oxygen mixtures in a 5-mm diameter, 2-mm tall silicone cylinder. The exothermic reaction quickly pressurizes the cylinder, displacing a silicone membrane up to 6 mm in under 1 ms. This device has an estimated free-inflation instantaneous stroke power of 3 W. The maximum reported operational frequency of these cylinders is 1.2 kHz with average displacements of ∼100 µm. We demonstrate that, at these small scales, the wall-quenching flame behavior also allows operation of a 3 × 3 array of 3-mm diameter cylinders with 4-mm pitch. Though we primarily present our device as a tactile display technology, it is a platform microactuator technology with application beyond this one.
现有的基于小型致动器的触觉刺激技术提供的刺激与人类皮肤巨大的机械感受器密度相比分辨率较低。软气动致动器阵列最初显示出作为小分辨率（1 到 3 毫米直径）、高顺应性触觉显示策略的潜力，但最终由于其需要比致动器本身更大的阀而失败。在本文中，我们展示了一种可单独寻址的软流体致动器阵列，该阵列无需机电阀即可运行。我们通过使用微尺度燃烧和局部热火焰淬火来实现这一点。具体来说，液态金属电极产生火花，点燃直径为 5 毫米、高 2 毫米的硅酮圆柱体内的贫燃料甲烷-氧气混合物。放热反应迅速加压圆柱，在不到 1 毫秒的时间内将硅橡胶膜向上推至 6 毫米。该设备的自由膨胀瞬时冲程功率估计为 3 W。这些圆柱体报告的最大操作频率为 1.2 kHz，平均位移约为 100 µm。我们证明，在这些小尺寸下，壁淬火火焰行为也允许以 4 毫米的间距操作 3×3 个直径为 3 毫米的圆柱体阵列。虽然我们主要将我们的设备作为触觉显示技术呈现，但它是一种平台微致动器技术，其应用不仅仅局限于此。
