Nanostructured Multifunctional Surface with Antireflective and Antimicrobial Characteristics

Abstract

Functional polymeric films with antireflective and hydrophobic properties have been widely used for electronic device displays. However, the design of such functional films with an antimicrobial characteristic has been a challenge. We designed a nanostructured surface using a rigorous coupled-wave analysis to obtain a period of 300 nm and an aspect ratio of 3.0 on a flat poly(methyl methacrylate) film. The fabricated nanostructure was hydrophobic and exhibited the desired optical characteristics with a reflectance of less than 0.5% over the visible wavelength range. Furthermore, the nanoimprinted polymer film exhibited antimicrobial characteristics and low adhesion when compared with the corresponding flat surface. The results suggest that the nanostructured surface designed in this study is multifunctional and should be suitable for the production of protective optical and hygienic polymer films for the displays of portable electronic devices.

Transparent Surfaces Inspired by Nature

“…It is evident that dust and contamination will reduce light transmission, but when considering transparent materials, there are myriad functions which could be tacked on to improve overall performance, such as modified thermal conductivity (e.g., windows, glazings, and solar thermal covers), flexibility (e.g., in curved and flexible displays), antifogging, self‐cleaning (i.e., (super)hydrophilicity/hydrophobicity), photocatalysis, mechanical/chemical hardness (i.e., antiabrasion, antisoiling, and anticorrosion), electrical properties (such as conductivity and antistatic control). Other useful functions include biocompatibility (e.g., contact lenses), sensing (e.g., biomolecular sensing), and antimicrobial coatings . For transparent materials, these areas are sure to grow as multifunctionality becomes more technically and commercially feasible.…”

Multifunctional biophotonic nanostructures inspired by the longtail glasswing butterfly for medical devices

“…We characterised in detail the surface and optical properties of the short-range-ordered nanostructures found on the C. faunus butterfly wings that could overcome the shortcomings of micro-optical implants. We reveal that C. faunus relies on relatively moderate-aspect-ratio (aspect-ratio ≈ 1) chitin nanostructures to produce (1) transparency that is a unique combination of wavelength-selective anti-reflection and angle-independent transmission resulting from isotropic Mie scattering, and (2) antifouling properties through disruption of cellular growth similar to that observed on high-aspect-ratio (aspect-ratio > 1) structures found in nature 12,13 . Drawing our inspiration from the C. faunus nanostructures, we created low-aspect-ratio (aspect-ratio < 1) bio-inspired nanostructures on freestanding Si 3 N 4 -membranes using a highly-scalable phase-separation-based polymer-assembly process.…”

“…A major deterrent to these efforts, however, has been the requirement to incorporate multiple functionalities within a tightly constrained footprint while ensuring acceptable in vivo performance and reliability 3–6 .Inspiration for engineering multifunctional surfaces is often drawn from nature, which boasts a plethora of nanostructures with a wide array of desirable properties 4–8 . For example, vertically-tapered needle-like nanostructures found on the wings of insects exhibit multifunctionality including omnidirectional antireflection, self-cleaning, antifouling, and bactericidal properties 9–13 . Such properties may prove to be advantageous for biomedical applications such as in vivo sensing, imaging, and stimulation.…”

“…Drawing our inspiration from the C. faunus nanostructures, we created low-aspect-ratio (aspect-ratio < 1) bio-inspired nanostructures on freestanding Si 3 N 4 -membranes using a highly-scalable phase-separation-based polymer-assembly process. Unlike previous high-aspect-ratio bio-inspired nanostructures replicating antireflection 9,12,13 , we engineered the pseudo-periodic arrangement and dimensions of nanostructures to control isotropic scattering and enhance omnidirectional optical transmission, which could benefit sensing and readout processes of micro-optical implants. In addition, improving from the anti-biofouling properties of high- and moderate-aspect-ratio nanostructures that typically rely on physical cell lysis 12,13,18 , we engineered the low-aspect-ratio nanostructures to generate strong nanostructure-mediated hydrophilicity and anti-adhesion barrier for proteins and cellular fouling without inducing cell lysis and inflammation.…”

Conducting polymer–gold co-patterned surfaces via nanosphere lithography

“…Nanopatterns are the building blocks of numerous state-of-the-art surface-based technologies including corrosion-resistant and antireflection coatings [1][2][3], tissue engineering scaffolds [4], sensors [5], and nanoelectronics [6]. Among these surfaces, multi-component nanopatterned arrays, in particular, have tremendous potential in the development of compact high memory systems and spintronics useful in biomedical diagnostics and supercomputing.…”