Butterfly Wing Surface Research Articles

Anti-reflective properties of butterfly-wing-micro-nano structures in the infrared band

The delicate and intricate micro-nano structure on the surface of butterfly wings is genuinely remarkable. Despite its potential for anti-reflection purposes, this surface structure's theoretical analysis, optimal design, and anti-reflection performance regulation remain a mystery. The anti-reflection characteristics of butterfly Papilio epiphorbas, butterfly Parthenos syvia, and butterfly Sasakia charonda butterfly wings in the infrared band were carefully examined using finite difference time domain simulation and equivalent medium theoretical calculation. The anti-reflection mechanism of the surface micro-nano structure parameters and infrared wavelength of the butterfly wings of butterfly Papilio epiphorbas, butterfly Parthenos syvia, and butterfly Sasakia charonda were revealed. By Fourier infrared reflectance test and simulation of the three butterfly wings, the results show that the structural color scales of the three butterfly wings can achieve a better anti-reflection effect in the infrared band. The anti-reflection performance of the extracted bionic butterfly wings is improved by 0.34%, 2.44%, and 5.46%, respectively, compared with the original butterfly wings. These findings provide valuable theoretical and data support for the continued development of the design and manufacture of bionic anti-reflective surface optics.

Mimicking the structure of Morpho butterfly wing surface: a highly reflective nanostructure assembled by nanospheres

Inspired by the surface structure of Morpho butterfly wings, we theoretically propose a biomimetic nanosphere structure with high optical reflectivity. By adjusting the geometric parameters and material parameters of the nanostructure, we obtain reflectivity >99 % in a certain band; the high-reflection bandwidth depends on the period width, filling factor, and number of nanospheres. Its high-reflectivity bandwidth is less dependent on the incidental light angle compared with general single-layer or multilayer coatings for reflection enhancement. Unlike the biomimetic structures that are completely the same as the Morpho butterfly surface, this simplified structure can be assembled in ways other than photolithography and electron-beam lithography. We also analyzed several deviations of the structure, and the results show that our design allowed these deviations, which is helpful to achieving the effect of the structure in the preparation process. At the same time, the equivalent medium theory was used to analyze the nanostructure. The nanosphere structure has excellent potential applications in optical devices that require high reflectivity, such as laser resonant cavity and optical filters.

Biomorphic CdS/Cd Photocatalyst Derived from Butterfly Wing for Efficient Hydrogen Evolution Reaction

AbstractPhotocatalytic splitting of water into hydrogen has attracted growing concerns as a promising strategy for the development of clean and renewable energy sources. Fabricating novel photocatalysts with high H2 evolution rate and good cyclic stability is extremely vital for practical applications. Herein, a novel CdS/Cd2SO4(OH)2 composite derived from cadmium nitrate doped Cd‐MOF is deposited on the surface of butterfly wings with reticular hierarchical structure for efficient hydrogen evolution reaction. The combination of unique hierarchical structure and MOF‐derived CdS nanoparticles endows them with strong light absorbability, small band gap, and superior photogenerated charges separation efficiency, leading to excellent photocatalytic efficiency. Furthermore, in‐depth measurements reveal the reduction of Cd2SO4(OH)2 to Cd on the surface of CdS particle during the photocatalytic process. The obtained Cd metal can act as the electron trap to improve the charge separation efficiency and further promote the hydrogen production performance. As a result, the MOF‐derived CdS/Cd2SO4(OH)2 and final CdS/Cd systems with reticular hierarchical structure exhibit significantly enhanced hydrogen production performance compared with CdS/Cd2SO4(OH)2 powder and MOF‐derived CdS nanoparticles under visible light irradiation. It is expected that this synthetic approach can be used to fabricate other composite photocatalyst materials with reticular hierarchical structure for efficient water splitting to hydrogen.

Biocompatibility and biosafety of butterfly wings for the clinical use of tissue-engineered nerve grafts.

In a previous study, we used natural butterfly wings as a cell growth matrix for tissue engineering materials and found that the surface of different butterfly wings had different ultramicrostructures, which can affect the qualitative growth of cells and regulate cell growth, metabolism, and gene expression. However, the biocompatibility and biosafety of butterfly wings must be studied. In this study, we found that Sprague-Dawley rat dorsal root ganglion neurons could grow along the structural stripes of butterfly wings, and Schwann cells could normally attach to and proliferate on different species of butterfly wings. The biocompatibility and biosafety of butterfly wings were further examined through subcutaneous implantation in Sprague-Dawley rats, intraperitoneal injection in Institute of Cancer Research mice, intradermal injection in rabbits, and external application to guinea pigs. Our results showed that butterfly wings did not induce toxicity, and all examined animals exhibited normal behaviors and no symptoms, such as erythema or edema. These findings suggested that butterfly wings possess excellent biocompatibility and biosafety and can be used as a type of tissue engineering material. This study was approved by the Experimental Animal Ethics Committee of Jiangsu Province of China (approval No. 20190303-18) on March 3, 2019.

Butterfly-wing pollination inScadoxusand other South African Amaryllidaceae

AbstractUnderstanding the evolution of floral morphology requires information about the identity of pollinators as well as the specific mechanisms of pollen transfer. Based on preliminary field observations and floral structure, we hypothesized that pollination mechanisms involving the transfer of pollen on butterfly wings occur in several lineages of South African Amaryllidaceae. Here we report findings from a detailed study of butterfly-wing pollination in two subspecies of Scadoxus multiflorus and review the prevalence of this pollination mechanism among other Amaryllidaceae in southern Africa. We established that S. multiflorus subsp. katherinae is genetically self-incompatible and thus entirely reliant on pollinators for seed production. We determined that this subspecies is pollinated almost exclusively by large swallowtail butterflies, principally males of the mocker swallowtail Papilio dardanus cenea. Flowers of S. multiflorus subsp. multiflorus are pollinated by pierid and swallowtail butterflies. Pollen is deposited on the ventral surface of the wings of butterflies as they flutter over the strongly exserted stamens. We predict that butterfly-wing pollination occurs in at least nine species of South African Amaryllidaceae, which may reflect several independent origins of this mechanism. The flowers of these species are red or orange with strong herkogamy and are either bowl-brush or open-brush in shape. We provide maps of the distribution of pollen on the ventral surface of the wings of pollinators for four of these species. All four appear to be pollinated via the ventral surface of large butterfly wings, with the floral structure facilitating the process. These findings illustrate the importance of investigating pollen transfer mechanisms in order to understand patterns of floral diversification and floral convergence.

Correction: Hydrophobic durability characteristics of butterfly wing surface after freezing cycles towards the design of nature inspired anti-icing surfaces.

[This corrects the article DOI: 10.1371/journal.pone.0188775.].

Band-gap analysis of a novel lattice with a hierarchical periodicity using the spectral element method

Inspired by the hierarchical structures of butterfly wing surfaces, a new kind of lattice structures with a two-order hierarchical periodicity is proposed and designed, and the band-gap properties are investigated by the spectral element method (SEM). The equations of motion of the whole structure are established considering the macro and micro periodicities of the system. The efficiency of the SEM is exploited in the modeling process and validated by comparing the results with that of the finite element method (FEM). Based on the highly accurate results in the frequency domain, the dynamic behaviors of the proposed two-order hierarchical structures are analyzed. An original and interesting finding is the existence of the distinct macro and micro stop-bands in the given frequency domain. The mechanisms for these two types of band-gaps are also explored. Finally, the relations between the hierarchical periodicities and the different types of the stop-bands are investigated by analyzing the parametrical influences.

Hydrophobic durability characteristics of butterfly wing surface after freezing cycles towards the design of nature inspired anti-icing surfaces.

The hydrophobicity and anti-icing performance of the surfaces of some artificial hydrophobic coatings degraded after several icing and de-icing cycles. In this paper, the frost formation on the surfaces of butterfly wings from ten different species was observed, and the contact angles were measured after 0 to 6 frosting/defrosting cycles. The results show that no obvious changes in contact angle for the butterfly wing specimens were not obvious during the frosting/defrosting process. Further, the conclusion was inferred that the topography of the butterfly wing surface forms a special space structure which has a larger space inside that can accommodate more frozen droplets; this behavior prevents destruction of the structure. The findings of this study may provide a basis and new concepts for the design of novel industrially important surfaces to inhibit frost/ice growth, such as durable anti-icing coatings, which may decrease or prevent the socio-economic loss.

A Comparative Study on the Wettability between Butterfly and Locust Wing Surface

The microstructure, hydrophobicity and chemical composition of the butterfly and locust wing surfaces were investigated by a scanning electron microscope (SEM), a contact angle meter and a Fourier transform infrared spectrometer (FT-IR). The hydrophobicity models were established on the basis of the Cassie equation. The wetting mechanism was comparatively discussed from the perspective of biological coupling. The butterfly and the locust wing surfaces are composed of naturally hydrophobic materials, but exhibit different complex wettability. The butterfly wing surface is of low adhesion (sliding angle 1~3°) and superhydrophobicity (contact angle 151.6~156.9°), while the locust wing surface is of extremely high adhesion (sliding angle>180°) and superhydrophobicity (contact angle 155.8~157.3°). The complex wettability of the wing surfaces ascribes to the coupling effect of hydrophobic material and rough structure. The butterfly and locust wings can be used as bio-templates for design and preparation of biomimetic functional surface, intelligent interfacial material and no-loss microfluidic transport channels.

Hydro-Oleophobic Property of Butterfly Wing Surface and Biomimetic Fabrication of Hydrophobic Silver Film

The hydrophobicity and oleophobicity(methanol repellency) of butterfly wing surfaces were measured by a video-basedcontact angle (CA) meter. The multi-dimensional microstructure of the wingsurfaces was characterized by a scanning electron microscope (SEM) and an atomic force microscope (AFM). The wingsurface exhibits superhydrophobicity (water CA 150.4~159.2°) and low adhesion (water sliding angle 1~3°). Meanwhile, the wingsurface displays high repellency against methanol. The critical concentrationsfor wetting and spreading-wetting of methanol solution on the wing surface are60% and 80%, respectively. The butterfly wing surface is ofhydro-oleophobicity. The wing surface possessescomplicated hierarchicalmicrostructures. Using the butterfly wing as a bio-template, the hydrophobicsilver films were prepared. Water CA increases from metal silver’s intrinsicCA 63.0° maximally to 139.2° (Speyeria aglaja, 5 nm silver film). The microstructures on thewing surface result in the transition of metal silver from hydrophilic tohydrophobic. The butterfly wing can be used as a template for design of smartinterface and functional surface.

The Relationship between Superhydrophobicity, Self-Cleaning Performance and Microstructure of Butterfly Wing

The microstructure and hydrophobicity of butterflywing surfaces were investigated by a scanning electron microscope (SEM), an atomicforce microscope (AFM) and a contact angle meter. The relationship between hydrophobicity,self-cleaning performance and microstructuralcharacteristic was analyzed. The butterfly wing surface is of lowadhesion (water SA 1~3°) and high hydrophobicity (water CA 138~157°). Theaverage rate of CaCO3 pollutionremoval from the wing surface is as high as 86.2%. There is a good positive correlation (R2=0.873)between pollution removal rate and roughness index of the wing surface. The coupling effects of hydrophobic material andrough microstructure contribute to the complex wettability and remarkableself-cleaning property of the wing surface. Butterfly wing can be potentiallyused as a template for design of micro-controllable superhydrophobic surfaceand nano self-cleaning material. This work may offer inspirations forbiomimetic fabrication of novel interfacial material with multi-functions.

Multiple-dimensional micro/nano structural models for hydrophobicity of butterfly wing surfaces and coupling mechanism

The microstructure, wettability and chemical composition of the butterfly wing surfaces were investigated by a scanning electron microscope, a contact angle meter and a Fourier transform infrared spectrometer. The micro/nano structural models for hydrophobicity of the butterfly wing surfaces were established on the basis of the Cassie equation. The hydrophobicity mechanisms were discussed from the perspective of biological coupling. The butterfly wing surfaces are composed of naturally hydrophobic material and possess micro/nano hierarchical structures, including primary structure (micrometric scales), secondary structure (nano longitudinal ridges and lateral bridges) and tertiary structure (nano stripes). The wing surfaces exhibit high hydrophobicity (contact angle 138°–157°) and low adhesion (sliding angle 1°–3°). The micromorphology and self-cleaning performance of the wing surfaces demonstrate remarkable anisotropism. The special complex wettability ascribes to a coupling effect of the material element and the structure element. In micro-dimension, the smaller the width and the bigger the spacing of the scale, the stronger the hydrophobicity of the wing surfaces. In nano-dimension, the smaller the height and the smaller the width and the bigger the spacing of the longitudinal ridge, the stronger the hydrophobicity of the wing surfaces. This work promotes our understanding of the hydrophobicity mechanism of bio-surfaces and may bring inspiration for biomimetic design and preparation of smart interfacial materials.

Complex Wettability and Self-Cleaning Performance of Butterfly Wing Surface

The microstructure, hydrophobicity and chemical composition of butterfly wing surfaces were investigated by a scanning electron microscope (SEM), a video-based contact angle meter, and a Fourier transform infrared spectrometer (FT-IR). Using CaCO3 particle as simulated pollutant, the self-cleaning performance of the wing surface was measured. The wing surfaces possess complicated micro/nanostructures. According to the large contact angles (140.2~156.9°) and small sliding angles (1~3°) of water droplet, the butterfly wing surface is of high hydrophobicity and low adhesion. The average rate of CaCO3 pollution removal from the wing surface is as high as 86.2%. There is a good positive correlation (r=0.89) between pollution removal rate and roughness index of the wing surface. The coupling effects of hydrophobic material and rough microstructure contribute to the special complex wettability and remarkable self-cleaning property of the wing surface. Butterfly wing can be used as a template for design of superhydrophobic surface and self-cleaning material. This work may offer inspirations for biomimetic fabrication of novel interfacial material with multi-functions.

2A2-G01 蝶の離陸時の飛翔力計測

We measured the differential pressures of butterfly's wing surface at the time of take off. Simultaneously, we photographed high-speed videos from two directions. To measure the pressure, we attached a MEMS (Micro Electro Mechanical Systems) differential pressure sensor on the wing surface. We analyzed the data with the videos to calculate the lift coefficient during the flight of a butterfly. Then we revealed the number of lift coefficient during the insects' free flight. The results suggest that the number of lift coefficient was bigger at the take off compared to during a flight. Furthermore, we revealed that the number of lift coefficient agrees with conventional study that have conducted in the same Reynolds number.

Preparation and characterization of hydrophobic nano silver film on butterfly wings as bio-template

Hydrophobic nano silver films were fabricated on butterfly wings as bio-template. The micrometric/nano structures and hydrophobicity of the surfaces were investigated with the help of scanning electron microscope(SEM) and video-based contact angle meter. The hydrophobic mechanism of silver film was analyzed with the aid of Cassie’s formula. On the nano silver films of various thicknesses(5, 10, 20, 40, 60, 80, 100 nm), all the contact angles( CAs) of water were bigger than 120°. When the silver film was 5 nm, the CAs of water on it on the wing surfaces of Mimathyma nycteis and Speyeria aglaja were 143.2° and 139.2°, respectively. Coated with the sliver film of the same thickness, butterfly wing surface exhibited the CA remarkably bigger than glass slide surface, exhibiting its high hydrophobicity. With the increase of silver film thickness on butterfly wing surface, the hydrophobicity kept decreasing. The micrometric/nano hierarchical structures on butterfly wing surface result in the transition of metal silver from hydrophilicity to hydrophobicity.

Asymmetric Ratchet Effect for Directional Transport of Fog Drops on Static and Dynamic Butterfly Wings

Inspired by novel creatures, researchers have developed varieties of fog drop transport systems and made significant contributions to the fields of heat transferring, water collecting, antifogging, and so on. Up to now, most of the efforts in directional fog drop transport have been focused on static surfaces. Considering it is not practical to keep surfaces still all the time in reality, conducting investigations on surfaces that can transport fog drops in both static and dynamic states has become more and more important. Here we report the wings of Morpho deidamia butterflies can directionally transport fog drops in both static and dynamic states. This directional drop transport ability results from the micro/nano ratchet-like structure of butterfly wings: the surface of butterfly wings is composed of overlapped scales, and the scales are covered with porous asymmetric ridges. Influenced by this special structure, fog drops on static wings are transported directionally as a result of the fog drops' asymmetric growth and coalescence. Fog drops on vibrating wings are propelled directionally due to the fog drops' asymmetric dewetting from the wings.

Studies of the anisotropic property when water droplet moves on butterfly wings

The morphology of the butterfly wings(Morpho Achilles) surface was observed by scanning electron microscope(SEM) and the wettability was characterized by the apparent contact angle.The adhesive forces between the water droplets and the surface of butterfly wings under different direction were characterized by a high-sensitivity microelectromechanical balance system.The experimental results show that the adhesive force when the water droplet moved along the direction of stacked scales was obviously smaller and more stable than that of other directions.If the wings were wetted,the adhesive forces were similar no matter in which direction the water droplets moved;the force along the direction of stacked scales even would be bigger than that against the direction of stacked scales.

Role of surface roughness on wettability and coefficient of restitution in butterfly wings

Surface nano-structure and roughness play a vital role in controlling the wettability and bouncing of water drops on wings of butterfly/moth species. A detailed experimental study was conducted to investigate the effect of nano-structure on static and dynamic contact angle measurements and coefficient of restitution of four different butterfly wing surfaces. Surface characterization at different length scales was performed using atomic force microscopy (AFM), optical profilometry and scanning electron microscopy. The water drop bouncing experiments were conducted on the surface of butterfly wings to investigate the coefficient of restitution. Contact angle measurements reveal that the wings which had high roughness factors resulted high static and dynamic (advancing and receding) contact angles with the exception of Antheraea Polyphemus. The wings that had a combination of scales and hair like microtrichia structure showed increased roughness and hydrophobicity compared to wings that had only either one of them.

G020034 チョウの離陸時における圧力差分布([G02003]バイオエンジニアリング部門一般セッション(3))

This paper reports on direct measurement of differential pressure distribution on a butterfly wing during takeoff. Differential pressure was measured with a micro-fabricated sensor. A MEMS (Micro Electro Mechanical Systems) piezo-resistive cantilever was used as the differential pressure sensor. The sensor chip was 1.0 mm x 1.0 mm x 0.3 mm in size and 0.7 mg in weight. The sensor was attached to a butterfly (Papilio protenor) wing surface through a Cu/Polyimide substrate and Au wires. The total weight was 30 mg so that it did not interfere with flight condition. The distribution of five points to the spanwise direction at the forewing and one point at the center of the hindwing was measured during takeoff. As a result, it was clarified that the maximum differential pressure was 20 Pa on the forewing tip. Additionally, the maximum aerodynamic force generated on the wing was 3 times larger than the gravity acting on the body.

Anisotropism of the Non-Smooth Surface of Butterfly Wing

Twenty-nine species of butterflies were collected for observation and determination of the wing surfaces using a Scanning Electron Microscope (SEM). Butterfly wing surface displays structural anisotropism in micro-, submicro- and nano-scales. The scales on butterfly wing surface arrange like overlapping roof tiles. There are submicrometric vertical gibbosities, horizontal links, and nano-protuberances on the scales. First-incline-then-drip method and first-drip-then-incline method were used to measure the Sliding Angle (SA) of droplet on butterfly wing surface by an optical Contact Angle (CA) measuring system. Relatively smaller sliding angles indicate that the butterfly wing surface has fine self-cleaning property. Significantly different SAs in various directions indicate the anisotropic self-cleaning property of butterfly wing surface. The SAs on the butterfly wing surface without scales are remarkably larger than those with scales, which proves the crucial role of scales in determining the self-cleaning property. Butterfly wing surface is a template for design and fabrication of biomimetic materials and self-cleaning substrates. This work may offer insights into how to design directional self-cleaning coatings and anisotropic wetting surface.