Fig. 6

Top-down fabrication techniques (photolithography, e-beam lithography (EBL), nanoimprinting). a Schematic illustration of fabrication processes with deep ultraviolet (DUV) lithography and dry etch. Reproduced with permission from [122], copyright American Chemical Society, 2019. b Schematic of high-index dielectric metasurface. Reproduced with permission from [123], copyright John Wiley and Sons, 2018. c Schematic diagram of the fabrication processes for flexible PDMS-based microdevices. Reproduced with permission from [81], copyright AIP Publishing, 2015. d Schematic illustration of the fabrication process for multi-scale hierarchical structure. Reproduced with permission from [124], copyright American Chemical Society, 2017. e Full processes of PDMS mold fabrication with direct etch and soft UV-NIL. Reproduced with permission from [125], copyright Elsevier, 2022