Microdroplet-guided intercalation and deterministic delamination towards intelligent rolling origami

Abstract

Three-dimensional microstructures fabricated by origami, including folding, rolling and buckling, gain great interests in mechanics, optics and electronics. We propose a general strategy on on-demand and spontaneous rolling origami for artificial microstructures aiming at massive and intelligent production. Deposited nanomembranes are rolled-up in great amount triggered by the intercalation of tiny droplet, taking advantage of a creative design of van der Waals interaction with substrate. The rolling of nanomembranes delaminated by liquid permits a wide choice in materials as well as precise manipulation in rolling direction by controlling the motion of microdroplet, resulting in intelligent construction of rolling microstructures with designable geometries. Moreover, this liquid-triggered delamination phenomenon and constructed microstructures are demonstrated in the applications among vapor sensing, microresonators, micromotors, and microactuators. This investigation offers a simple, massive, low-cost, versatile and designable construction of rolling microstructures for fundamental research and practical applications.

Intelligent Shape-Morphing Micromachines

“…However, the bending direction angle along with the long axis of twisting is adjustable, and it finally exhibits a helix shape. Xu et al [ 58 ] proposed a microdroplet-guided shape-morphing strategy of microstructures for programmable twisting ( Figure 2(h) ). The twisting direction can be precisely controlled by selecting a trigger point of microdroplets.…”

“…It creates spatial variability of the ambient environment for the intelligent micromachines, which could trigger orientable or sequential shape morphing of structures. Since the surface tension dominates rather than the bulk force at the small scale, capillarity becomes an effective mechanism to trigger shape morphing [ 58 , 79 – 81 ]. Utilizing the capillary forces, Honschoten et al [ 51 ] developed an origami-based technique for planer microstructures folding into 3D objects ( Figure 3(a) ).…”

“…Here, we list eight types of applications of intelligent micromachines which are divided into motion- and target-based micromachines, as shown in Figure 4 . The motion-based micromachines include microswimmers for swimming in the liquid [ 23 , 30 , 41 – 44 ], microcrawlers for substrate locomotion [ 57 , 64 ], microjumpers for jumping [ 64 , 86 ], and micromotors for marching [ 52 , 53 , 58 , 87 ], while the target-based micromachines include microvalves for valve control of microchannels [ 35 , 36 ], microstents for extending vessels [ 54 , 88 ], microgrippers for drugs catching [ 26 , 47 , 49 , 56 , 66 ], and microcarriers for drug carrying and delivery [ 29 , 89 , 90 ]. Each application is summarized and marked with its common strategies according to the shape-morphing dimension, shape-morphing modes, and realization methods discussed above, together with their advantages and limitations (see Table 1 for details).…”

Programmable 3D Self‐Folding Structures with Strain Engineering

“…Here, e‐beam evaporation was applied to deposit a film consisting of Ag, SiO 2 , and Cr on glass substrate. [ 43 ] The thickness of each layer was tuned as 40 nm, which means that the total thickness is 120 nm. A residual stress gradient along the z axis was established during the deposition as a consequence of thermal expansion mismatch.…”

“…Such self-rolling structures have been demonstrated to have applications in vapor sensing, microresonators, micromotors, and microactuators. [43] Another potential application is to use these neutral stable structures in energy harvesting [44][45][46] by using piezoelectric materials in them, as these structures have minimum twisting stiffness and will manifest deformation and therefore energy-harvesting efficiency from the environment. It is also anticipated that by incorporating these smart structural elements, a variety of novel structures and devices, including mechanical metamaterials [47] and flexible robotics, [48,49] can be obtained.…”