Top-Down Fabrication of Ordered Nanophotonic Structures for Biomedical Applications

Abstract

The size, distribution, and specific shape of ordered nanophotonic structures are crucial for their biomedical applications. Bottom-up approaches such as self-assembly, emulsification, and precipitation are commonly fabricated nanophotonic structures, which often lack control of nanophotonic structures morphologies and monodispersed sizes. On the contrary, top-down nanofabrication techniques offer the advantages of high fidelity and high controllability and are employed in the fabrication of nanophotonic structures. This review focuses on top-down nanofabrication techniques to fabricate ordered nanophotonic structures and their biomedical applications. Several top-down approaches used in the semiconductor industry and other fields requiring micro- and nanopatterns are used, including electron beam lithography/ion beam lithography, photolithography, interference lithography, nanoimprint lithography, nanosphere lithography, nanotransfer lithography, and nano-electrodeposition. Various current and emerging biomedical applications of the ordered nanophotonic structures are also covered: i) surface-enhanced Raman scattering, ii) plasmonics, including surface plasmon resonance and localized surface plasmon resonance, and iii) fluorescence enhancement. Finally, a future perspective of nanophotonic structures fabricated by top-down techniques in biomedical applications is also summarized.