Kirigami/origami: unfolding the new regime of advanced 3-D micro-/nanofabrication with 'folding'
3-D micro-/nanofabrication holds the key to building a large variety of micro-/nanoscale materials, structures, devices, and systems with unique properties that do not manifest in their 2-D planar counterparts. Recently, scientists have explored some very different 3-D fabrication strategies such as kirigami and origami that make use of the science of cutting and folding 2-D materials/structures to create versatile 3-D shapes. Such new methodologies enable continuous and direct 2-D-to-3-D transformations through folding, bending and twisting, with which the occupied space can vary "nonlinearly" by several orders of magnitude compared to the conventional 3-D fabrications. More importantly, these new-concept kirigami/origami techniques provide an extra degree of freedom in creating unprecedented 3-D micro-/nanogeometries beyond the imaginable designs of conventional subtractive and additive fabrication.