Graphene-based bimorphs for micron-sized, autonomous origami machines
Graphene-based bimorphs for micron-sized, autonomous origami machines
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DOI：
10.1073/pnas.1712889115
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发表时间：
2018-01-16
影响因子：
11.1
通讯作者：
Cohen, Itai
中科院分区：
文献类型：
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作者：
Miskin, Marc Z.;Dorsey, Kyle J.;Cohen, Itai
折纸灵感的制造为折叠机提供了一个有吸引力的平台：更薄的折叠材料层导致更小的设备，前提是保持关键的功能方面，如导电性，刚度和灵活性。在这里，我们展示了使用二维原子膜作为折叠材料的折纸制造的极限。作为原型，我们将石墨烯片粘合到纳米厚的玻璃层上，以制造双晶致动器，该致动器可以弯曲到微米曲率半径，以响应小的应变差。这些应变比器件的断裂阈值低两个数量级，因此保持了整个结构的导电性。通过在双晶晶片顶部图案化2 μ m厚的刚性面板，我们将弯曲定位到未图案化的区域以产生折叠。虽然石墨烯双晶型只有纳米厚，但它们可以举起这些面板，重量相当于500纳米厚的硅芯片。使用面板和双晶片，我们可以缩小现有的折纸模式，以生产各种各样的机器。当超过可调的pH阈值时，这些机器会在几分之一秒内改变形状，这表明它们能够感知环境、做出反应，并在与微型生物有机体相当的时间和长度尺度上执行有用的功能。随着电子、光子和化学有效载荷的结合，这些基本元件将成为微米级机器人的强大平台。
Origami-inspired fabrication presents an attractive platform for miniaturizing machines: thinner layers of folding material lead to smaller devices, provided that key functional aspects, such as conductivity, stiffness, and flexibility, are persevered. Here, we show origami fabrication at its ultimate limit by using 2D atomic membranes as a folding material. As a prototype, we bond graphene sheets to nanometer-thick layers of glass to make ultrathin bimorph actuators that bend to micrometer radii of curvature in response to small strain differentials. These strains are two orders of magnitude lower than the fracture threshold for the device, thus maintaining conductivity across the structure. By patterning 2-mu m-thick rigid panels on top of bimorphs, we localize bending to the unpatterned regions to produce folds. Although the graphene bimorphs are only nanometers thick, they can lift these panels, the weight equivalent of a 500-nm-thick silicon chip. Using panels and bimorphs, we can scale down existing origami patterns to produce a wide range of machines. These machines change shape in fractions of a second when crossing a tunable pH threshold, showing that they sense their environments, respond, and perform useful functions on time and length scales comparable with microscale biological organisms. With the incorporation of electronic, photonic, and chemical payloads, these basic elements will become a powerful platform for robotics at the micrometer scale.