Moreover, all these 3D techniques follow a вЂњlinearвЂќ rule, i.e. In sophisticated complementary metalвЂ“oxideвЂ“semiconductor (CMOS) techniques, for example, the miniaturization of functional transistors is approaching the physical limit, which is restricted not only by the resolution of deep ultraviolet (UV) lithography but also by the finite size of silicon atoms and lattices. Although very mature, highly precise, and widely compatible, these techniques are now approaching the bottleneck of fundamental law limits. While numerous cutting-edge studies have emphasized the necessity and significance of 3D configurations, traditional on-chip 3D microfabrication/nanofabrication techniques rely mostly on a few topвЂ“down (subtractive manufacturing) and bottomвЂ“up (additive manufacturing) strategies, such as layer-by-layer lithography/stacking 15, 3D translational writing 16, and their combinations. Although the emerging 2D planar metasurfaces have avoided fabrication difficulties 8, 9, 10, 11, recent advances in device-level integration and reconfiguration (such as metasurfaces integrated with micro-electromechanical systems and spatial light modulators) 12, 13, 14 have once again led to an urgent need for functionality expansion in the third dimension. In photonic areas, for instance, the momentum for research on 3D photonic crystals and 3D metamaterials at optical frequencies has largely been weakened in the past decades, mainly due to the challenges in traditional 3D nanofabrication 7. In fact, 3D microfabrication/nanofabrication is so important that it has exerted a dramatic impact on the direction of many research fields. Even in the explosively growing areas of 2D materials, for example, the recent demonstration of graphene kirigami 4 and origami 5 has opened a new dimension of material engineering promising for unconventional electronic, mechanical, and optical properties such as superconductivity triggered by вЂњmagicвЂќ twisting 6. Three-dimensional (3D) microfabrication/nanofabrication holds the key to building a large variety of microscale/nanoscale materials, structures, devices, and systems with new, better, and flexible optical, thermal, acoustic, electric, magnetic, and mechanical functionalities compared with their macroscopic counterparts and two-dimensional (2D) planar counterparts 1, 2, 3. With the unprecedented physical characteristics and applicable functionalities generated by kirigami/origami, a wide range of applications in the fields of optics, physics, biology, chemistry and engineering can be envisioned. The progress in microscale/nanoscale kirigami/origami for reshaping the emerging 2D materials, as well as the potential for biological, optical and reconfigurable applications, is briefly discussed. As an instant and direct method, ion-beam irradiation-based tree-type and close-loop nano-kirigami is highlighted in particular. These stimuli enable direct 2D-to-3D transformations through folding, bending, and twisting of microstructures/nanostructures, with which the occupied spatial volume can vary by several orders of magnitude compared to the 2D precursors.

Various stimuli of kirigami/origami, including capillary forces, residual stress, mechanical stress, responsive forces, and focussed-ion-beam irradiation-induced stress, are introduced in the microscale/nanoscale region.

In this paper, we review the latest progress in kirigami/origami on the microscale/nanoscale as a new platform for advanced 3D microfabrication/nanofabrication. Advanced kirigami/origami provides an automated technique for modulating the mechanical, electrical, magnetic and optical properties of existing materials, with remarkable flexibility, diversity, functionality, generality, and reconfigurability.

Sources chinabased linkdoc