Design for Approaching Cicada-Wing Reflectance in Low- and High-Index Biomimetic Nanostructures

Abstract

Natural nanostructures in low refractive index Cicada wings demonstrate ≤ 1% reflectance over the visible spectrum. We provide design parameters for Cicada-wing-inspired nanotip arrays as efficient light harvesters over a 300-1000 nm spectrum and up to 60° angle of incidence in both low-index, such as silica and indium tin oxide, and high-index, such as silicon and germanium, photovoltaic materials. Biomimicry of the Cicada wing design, demonstrating gradient index, onto these material surfaces, either by real electron cyclotron resonance microwave plasma processing or by modeling, was carried out to achieve a target reflectance of ∼ 1%. Design parameters of spacing/wavelength and length/spacing fitted into a finite difference time domain model could simulate the experimental reflectance values observed in real silicon and germanium or in model silica and indium tin oxide nanotip arrays. A theoretical mapping of the length/spacing and spacing/wavelength space over varied refractive index materials predicts that lengths of ∼ 1.5 μm and spacings of ∼ 200 nm in high-index and lengths of ∼ 200-600 nm and spacings of ∼ 100-400 nm in low-index materials would exhibit ≤ 1% target reflectance and ∼ 99% optical absorption over the entire UV-vis region and angle of incidence up to 60°.

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

“…1a) belongs to the Riodinidae family found in South America. We have discovered that the C. faunus wings are distinct from most other transparent wings in nature 9,11,22 . They have a rare combination of two transparent regions that transmit light differently: (1) the basal transparent areas close to thorax (indicated by a blue arrow in Fig.…”

“…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.…”

Recent biomedical applications of bio-sourced materials

“…1C) [15][16][17]. Liu et al developed a new type of imprinting with cicada wings and fabricated nanoarrays that are transferrable to a silicon surface and subsequently showed antireflective properties [15].…”

Fabrication of Organic Solar Cells with Branched Cauliflower-Like Nano Structures as a Back Electrode Replicated from a Natural Template of Cicada Wing Patterns

“…Cicada wing including quasi-ordered surface nano-nipple arrays has been used as a replicable natural template [20,22,23]. Cicada wing has been employed as an antireflective and easily separable substrate from a deposited layer as a result of its low surface tension material that can serve naturally as an anti-sticking coating [22,24,25], and also as a light harvesting in photovoltaic devices [26].…”