Kim Seong Jae, Kim Taehoon, Ryu Hyun Jun, Jeong Ji-Hun, Hart A John, Kim Sanha
Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea.
Department of Mechanical Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA, 02139, USA.
Adv Sci (Weinh). 2025 Sep;12(36):e08338. doi: 10.1002/advs.202508338. Epub 2025 Jun 25.
Surfaces become "sticky" at the micro/nano length scale as the gravitational force is no longer effective. Ultragentle, high-contrast switching of interfacial adhesion is the key to reliable small-scale object manipulation. Here, a novel approach is presented for surface adhesion control utilizing a liquid-permeable nanoporous surface, which can switch from off-state adhesion (< 0.002 kPa) to on-state attraction (0.8 kPa) without preload. The surface of the gripper is composed of vertically aligned composite nanowires with an average diameter of 79 nm. When a liquid is injected into the nanoporous membrane, capillary adhesion occurs, allowing the object to be picked up. As the liquid evaporates, the object can be released by extremely sparse contact. The off-state adhesion of a millimeter-scale gripper is even lower than the gravitational force of thin polymer films (0.18 mN cm), enabling the solid-contactless release of lightweight materials. We characterize and model the mechanism across length scales and provide pick-and-place demonstrations including LED chips, micro-architected materials, and thin-film electronics.
在微纳长度尺度下，由于重力不再起作用，表面会变得“粘性”。界面粘附力的超轻柔、高对比度切换是可靠地操控小尺度物体的关键。在此，提出了一种利用可渗透液体的纳米多孔表面来控制表面粘附力的新方法，该表面无需预加载即可从关闭状态的粘附力（<0.002 kPa）切换到开启状态的吸引力（0.8 kPa）。抓取器的表面由平均直径为79 nm的垂直排列的复合纳米线组成。当向纳米多孔膜中注入液体时，会发生毛细粘附，从而能够拾取物体。随着液体蒸发，物体可以通过极其稀疏的接触而被释放。毫米级抓取器的关闭状态粘附力甚至低于薄聚合物薄膜的重力（0.18 mN cm），从而能够对轻质材料进行无固体接触的释放。我们对跨长度尺度的机制进行了表征和建模，并提供了包括LED芯片、微结构材料和薄膜电子产品在内的拾取和放置演示。
