Butterfly Wing Research Articles

A Novel Ultra-Wideband Electromagnetic-Wave-Absorbing Metastructure Inspired by Bionic Gyroid Structures.

Traditional honeycomb-like structural electromagnetic (EM)-wave-absorbing materials have been widely used in various equipment as multifunctional materials. However, current EM-wave-absorbing materials are limited by narrow absorption bandwidths and incidence angles because of their anisotropic structural morphology. The work presented here proposes a novel EM-wave-absorbing metastructure with an isotropic morphology inspired by the gyroid microstructures seen in Parides sesostris butterfly wings. A matching redesign methodology between the material and subwavelength scale properties of the gyroid microstructure is proposed, inspired by the interaction mechanism between the microstructure and the material properties on the EM-wave-absorption performance of the prepared metastructure. The bioinspired metastructure is fabricated by additive manufacturing (AM) and subsequent coating through dipping processes, filled with dielectric lossy materials. Based on simulations and experiments, the metastructure designed in this work exhibits an ultrawide absorption bandwidth covering the frequency range of 2-40GHz with a fractional bandwidth of 180% at normal incidence. Moreover, the metastructure has a stable frequency response when the incident angle is 60° under transverse electric (TE) and transverse magnetic (TM) polarization. Finally, the synergistic mechanism between the microstructure and the material is elucidated, which provides a new paradigm for the design of novel ultra-broadband EM-absorbing materials.

Investigating the Effect of Reflectance Tuning on Photocatalytic Dye Degradation with Biotemplated ZnO Photonic Nanoarchitectures Based on Morpho Butterfly Wings.

Photonic nanoarchitectures of butterfly wings can serve as biotemplates to prepare semiconductor thin films of ZnO by atomic layer deposition. The resulting biotemplated ZnO nanoarchitecture preserves the structural and optical properties of the natural system, while it will also have the features of the functional material. The ZnO-coated wings can be used directly in heterogeneous photocatalysis to decompose pollutants dissolved in water upon visible light illumination. We used the photonic nanoarchitectures of different Morpho butterflies with different structural colors as biotemplates and examined the dependence of decomposition rates of methyl orange and rhodamine B dyes on the structural color of the biotemplates and the thickness of the ZnO coating. Using methyl orange, we measured a ten-fold increase in photodegradation rate when the 20 nm ZnO-coated wings were compared to similarly coated glass substrates. Using rhodamine B, a saturating relationship was found between the degradation rate and the thickness of the deposited ZnO on butterfly wings. We concluded that the enhancement of the catalytic efficiency can be attributed to the slow light effect due to a spectral overlap between the ZnO-coated Morpho butterfly wings reflectance with the absorption band of dyes, thus the photocatalytic performance could be changed by the tuning of the structural color of the butterfly biotemplates. The photodegradation mechanism of the dyes was investigated by liquid chromatography-mass spectroscopy.

Broken Butterfly Wings: Exploring the Role of Textile Blends in the Circular Economy for Recycling and Disassembly

In the context of a transition to a more sustainable fashion and textile industry, blended textiles (materials where two or more different resources are combined) are a major issue. These are described as “monstrous hybrids” and used to create “Frankenstein products” that are difficult to recover and recycle. The circular economy champions mono-materiality. It asks that technical and biological materials are kept in separate cycles, as shown in the Ellen MacArthur Foundation’s “butterfly model”; named because of its two wing-like sides. But in reality, materials are mixed in most of the textiles that surround us, and fully mono-material design is unrealistic in many cases. The butterfly wings are broken. This paper explores the various ways textile designers make blended textiles and acknowledges their role and creativity when providing solutions for aesthetic and technical requirements. The study draws on the first two authors’ PhD practice research that explored these issues from complementary re-active and pro-active approaches. Both carried out at the University of the Arts London, one project investigated Textile Design for Disassembly and the other Design for Recycling Knitwear. Using an after-action review approach, joint insights from both projects are presented. The paper investigates blending across three themes: hierarchy, technique and fibre type. It focuses on why these themes are relevant to designers and explores their different levels of complexity, before demonstrating how multiple perspectives are necessary to address the complex and systemic issues tied to blend recyclability. The paper concludes that blending and recovery are not mutually exclusive and that blended textiles can, with forethought, form part of the circular economy.

4D Printing of Butterfly Scale-Inspired Structures for Wide-Angle Directional Liquid Transport.

Unidirectional liquid transport has been extensively explored for water/fog harvesting, electrochemical sensing, and desalination. However, current research mainly focuses on linear liquid transport (transport angle α= 0°), which exhibits hindered lateral liquid spreading and low unidirectional transport efficiency. Inspired by the wide-angle (0°< α< 180°) liquid transport on butterfly wings, this work successfully achieves linear (α= 0°), wide-angle, and even ultra-wide-angle (α= 180°) liquid transport by four-dimensional (4D)printing of butterfly scale-inspired re-entrant structures. These asymmetric re-entrant structures can achieve unidirectional liquid transport, and their layout can control the Laplace pressure in the forward (structure-tilting) and lateral directions to adjust the transport angle. Specifically, high transport efficiency and programmable forward/lateral transport paths are simultaneously achieved by the ultra-wide-angle transport, where liquid fills the lateral path before being transported forward. Moreover, the ultra-wide-angle transport is also validated in 3D space, which provides an innovative platform for advanced biochemical microreaction, large-area evaporation, and self-propelled oil-water separation.

Protein Delivery to Insect Epithelial Cells In Vivo: Potential Application to Functional Molecular Analysis of Proteins in Butterfly Wing Development

Protein delivery to cells in vivo has great potential for the functional analysis of proteins in nonmodel organisms. In this study, using the butterfly wing system, we investigated a method of protein delivery to insect epithelial cells that allows for easy access, treatment, and observation in real time in vivo. Topical and systemic applications (called the sandwich and injection methods, respectively) were tested. In both methods, green/orange fluorescent proteins (GFP/OFP) were naturally incorporated into intracellular vesicles and occasionally into the cytosol from the apical surface without any delivery reagent. However, the antibodies were not delivered by the sandwich method at all, and were delivered only into vesicles by the injection method. A membrane-lytic peptide, L17E, appeared to slightly improve the delivery of GFP/OFP and antibodies. A novel peptide reagent, ProteoCarry, successfully promoted the delivery of both GFP/OFP and antibodies into the cytosol via both the sandwich and injection methods. These protein delivery results will provide opportunities for the functional molecular analysis of proteins in butterfly wing development, and may offer a new way to deliver proteins into target cells in vivo in nonmodel organisms.

Mechanism of Microstructural Alterations of M50 Bearing Steel during Rolling Contact Fatigue under High Loads

Rolling contact fatigue (RCF) of vacuum induction melted–vacuum arc remelted (VIM-VAR) M50 bearing steel under high loads was carried out, using a three-ball-rod RCF tester. Dark etching regions (DER) and butterflies were found in the subsurface region below the raceway of the RCF-tested sample. The DER appeared in the region of maximum shear stress located at a depth of 30 μm to 170 μm below the raceway. Carbon atoms migrated through high-density dislocations, and part of the martensite plates was transformed into cellular ferrites, due to the redistribution of dislocations during the deformation of martensite under the action of cyclic shear stress. Butterflies appeared in the region of maximum shear stress located at a depth of 20 μm to 314 μm below the raceway. Butterflies were initiated in the primary carbides, with length values ranging from 5 μm to 15 μm. The plate martensite in the butterfly wings was transformed into nanocrystalline ferrites, due to the increase in the dislocation density and rearrangement of dislocations during the extension of fatigue cracks from the primary carbides to the matrix under cyclic shear stress.

The genetic basis of wing spots in Pieris canidia butterflies

Spots in pierid butterflies and eyespots in nymphalid butterflies are likely non-homologous wing colour pattern elements, yet they share a few features in common. Both develop black scales that depend on the function of the gene spalt, and both might have central signalling cells. This suggests that both pattern elements may be sharing common genetic circuitry. Hundreds of genes have already been associated with the development of nymphalid butterfly eyespot patterns, but the genetic basis of the simpler spot patterns on the wings of pierid butterflies has not been investigated. To facilitate studies of pierid wing patterns, we report a high-quality draft genome assembly for Pieris canidia, the Indian cabbage white. We then conducted transcriptomic analyses of pupal wing tissues sampled from the spot and non-spot regions of P. canidia at 3-6 h post-pupation. A total of 1352 genes were differentially regulated between wing tissues with and without the black spot, including spalt, Krüppel-like factor 10, genes from the Toll, Notch, TGF-β, and FGFR signalling pathways, and several genes involved in the melanin biosynthetic pathway. We identified 14 genes that are up-regulated in both pierid spots and nymphalid eyespots and propose that spots and eyespots share regulatory modules despite their likely independent origins.

Inside Front Cover, Volume 2, Number 2, April 2023

Inside Front Cover: The cover image is based on the Research Article Bionic surface diode for droplet steering by Yang et al. Ultraslippery patterned surfaces with significant droplet sliding anisotropy were created by coordinating the heterogeneous wettability of the back of dessert beetle, directional-dependent architecture of butterfly wing, and ultraslippery configuration of Nepenthes alata. The sliding anisotropy of the functional surface is threefold higher than that of natural butterfly wings, which enables the simultaneous handling of multiple droplets without mass loss. (DOI: 10.1002/dro2.46)

Onchobothrium malakhovi n. sp. (Cestoda: Onchoproteocephalidea) ex Bathyraja (Arctoraja) sexoculata (Rajiformes: Arhynchobatidae) from Kuril Islands (Russia), with comments on the status of the genus Onchobothrium.

Onchobothrium malakhovin. sp. was found in the spiral valve of the softnose skate Bathyraja (Arctoraja) sexoculata off the Simushir Island (Kuril Islands, Russia). The new species has bothridia with three loculi and no additional suckers on bothridia, single-toothed hooks unconnected by their bases, no spines at the bases of the hooks, dense matrix around the hook bases shaped as an unpaired butterfly wing, and a short and wide ovary. Onchobothrium malakhovin. sp. differs from O. antarcticum and O. magnum in having a smaller total length, cirrus sac and ovary, smaller testes and eggs. Additionally, the new species differs from O. antarcticum by the absence of a vaginal sphincter and shorter bothridia; differs from O. magnum in having fewer proglottids and smaller vitelline follicles. It differs from O. farmeri, O. convolutum, and O. pseudouncinatum, by the absence of a small spine at the base of the hooks and the absence of accessory suckers on bothridia; from O. pseudouncinatum, additionally, by unconnected hooks; from O. schizacanthium, by the number of testes and by the presence of a postvaginal group of testes. Onchobothrium malakhovin. sp. was placed among other members of the Onchoproteocephalidea with a high support based on the sequence data for the D1-D3 region of the 28S rDNA and cox1 gene. The phylogenetic position of the genus Onchobothrium sensu lato remains ambiguous. We suggest that Onchobothrium sensu lato is a complex genus containing at least two morphologically different groups of species. Onchobothrium farmer, O. convolutum, O. schizacanthium, and O. pseudouncinatum, for which there are no molecular genetic data, are considerably different morphologically from O. malakhovin. sp., O. antarcticum, and O. magnum. A new genus might have to be established for the latter three species after the accumulation of genetic data.

Achieving structural white inspired by quasiordered microstructures in Morpho theseus

As one of the most fascinating phenomena, structural whiteness in natural organisms serves important functions in thermoregulation and mating. However, the architectures that cause visible broadband reflection are often in quasiordered distributions, which hinders systematic research on their color formation mechanisms. Here, through numerical analysis, the architectures in Morpho theseus scales are shown to be distributed in various tubular morphologies between tubular and gyroid structures. Then, the mechanism of structural white is discussed using the numerical model built with the combination of a periodic numerical framework and random elements. Thermodynamic experiments indicate that the white scales can efficiently help reduce the temperature of butterfly wings under a direct light beam. Our work provides a concise method for analyzing quasiordered structures. The methodology developed by this numerical model can facilitate a deep understanding of the performance improvement facilitated by these structural characteristics. Corresponding solutions can guide the design of nano-optical materials to achieve an efficient cooling, camouflage, and photothermal conversion system.

Gyroid-structured nanoporous chitosan from block copolymer template for UVC reflection

Bioinspired from structural coloration of butterfly wing structure, this work aims to fabricate nanoporous chitosan for UVC reflection. By taking advantage of self-assembled polystyrene-b-polydimethylsiloxane (PS-b-PDMS) with double gyroid texture followed by hydrofluoric acid etching of PDMS block, nanoporous PS with well-defined nanochannels can be fabricated, and used as a template for templated crosslinking reaction of chitosan through a multiple pore-filling process. Well-ordered nanoporous chitosan with shifting networks in nanoscale can be successfully fabricated after removal of the PS template. With the low absorption of chitosan in the ultraviolet region and the shifting networks for opening the bandgap, it is appealing to exploit the nanonetwork chitosan as high reflective materials for UVC optical devices, as evidenced by finite-difference time-domain (FDTD) simulation and optical measurements experimentally.

Bio‐inspired Porous Composite Electrode for Enhanced Mass Transfer and Electrochemical Water Purification by Modifying Local Flow Pattern

AbstractPorous electrodes offer a new opportunity for flow‐through electrochemical water purification, but their irregular porous‐structure makes the local flow pattern and mass transfer performance inhomogeneous, unpredictable, and uncontrollable. In this study, a bio‐inspired design is reported for porous electrode by learning the micro‐scale architectures of the wings of butterfly and owl based on analogy between heterogeneous mass transfer and sound absorption. Results demonstrate that combining gyroid and perforated plate can produce strong periodic vortex and inertial flow in interpenetrating channels even at laminar flow region. This enables homogeneous, predictable and controllable flow patterns and enhanced mass transfer, which can be explained by uniformity analysis and physical field synergy. Based on experimental tests on Cu electrode fabricated by selective laser melting, the composite gyroid electrode generates the limiting current density of 83% higher than random porous‐structured electrode, accounting for nitrate removal as high as 95% by electrochemical denitrification. This study represents a paradigm shift to advance design for porous architectures by learning experiences of hydrodynamic behaviors from nature. In this way, it is feasible to enhance mass transfer by modifying local flow patterns on pore scale, which may have broader implications that extend to other heterogeneous reaction systems.

Magnetohydrodynamic Instabilities of Double Magnetic Bands in a Shallow-water Tachocline Model. I. Cross-equatorial Interactions of Bands

Along with a butterfly diagram of sunspots, combined observational studies of ephemeral active regions, X-ray and EUV bright points, plage, filaments, faculae, and prominences demonstrate a pattern, which is known as the Extended Solar Cycle. This pattern indicates that the wings of the sunspot butterfly could be extended to much higher latitudes (up to ∼60°), to an earlier time than the start of a sunspot cycle, hence yielding a strong overlap between cycles. Thus, during the ongoing cycle’s activity near 30° latitude in each hemisphere, the next cycle kicks off at around 60°. By representing these epochs of overlaps by oppositely directed double magnetic bands in each hemisphere, we compute the unstable eigenmodes for MHD Rossby waves at the base of the convection zone and study how the properties of these energetically active Rossby waves change as these band pairs migrate equatorward. We find that in each hemisphere the low-latitude band interacts with the high-latitude band and drives the MHD instability as the solar activity progresses from 35°–15° latitude, which is essentially the rising phase. When the activity proceeds further equatorward from 15°, the interaction between low- and high-latitude bands weakens, and the cross-equatorial interaction between two low-latitude bands in each hemisphere starts. The eigenmodes in the latitude-longitude plane also reflect such changes in their pattern as the bend of the active cycle moves below 15° latitude.

Butterfly Wing Translucence Enables Enhanced Visual Signaling.

The light reflected by the dorsal side of butterfly wings often functions as a signal for, e.g., mate choice, thermoregulation, and/or predator deterrence, while the ventral wing reflections are generally used for crypsis and camouflage. Here, we propose that transmitted light can also have an important role in visual signaling because, in many butterfly species, the dorsal and ventral wing sides are similarly patterned and locally more or less translucent. Extreme examples are the Japanese yellow swallowtail (Papilio xuthus Linnaeus, 1758) and the Yellow glassy tiger (Parantica aspasia Fabricius, 1787). Their wings exhibit a similar color pattern in reflected and transmitted light, which allows enhanced visual signaling, especially in flight. Contrasting cases in which the coloration and patterning of dorsal and ventral wings strongly differ are the papilionid Papilio nireus Linnaeus, 1758, and the pierid Delias nigrina Fabricius, 1775. The wings observed in reflected or transmitted light then show very different color patterns. Wing translucence thus will strongly affect a butterfly's visual signal.

Pixelating Responsive Structural Color via a Bioinspired Morphable Concavity Array (MoCA) Composed of 2D Photonic Crystal Elastomer Actuators.

Stimuli-responsive structural coloration allows the color change of soft substrates in response to environmental stimuli such as heat, humidity, and solvents. Such color-changing systems enable smart soft devices, such as the camouflageable skin of soft robots or chromatic sensors in wearable devices. However, individually and independently programmable stimuli-responsive color pixels remain significant challenges among the existing color-changing soft materials and devices, which are crucial for dynamic display. Inspired by the dual-color concavities on butterfly wings, a morphable concavity array to pixelate the structural color of two-dimensional photonic crystal elastomer and achieve individually and independently addressable stimuli-responsive color pixels is designed. The morphable concavity can convert its surface between concave and flat upon changes in the solvent and temperature, accompanied by angle-dependent color-shifting. Through multichannel microfluidics, the color of each concavity can be controllably switched. Based on the system, the dynamic display by forming reversibly editable letters and patterns for anti-counterfeiting and encryption are demonstrated. Itis believed that the strategy of pixelating optical properties through locally altering surface topography can inspire the design of new transformable optical devices, such as artificial compound eyes or crystalline lenses for biomimetic and robotic applications.

Hierarchical Wrinkling‐Cracking Architectures for Flexible Pressure Sensors

AbstractInspired by butterfly wing architectures, a facile but efficient approach is developed to realize three sensing characteristics in a single pressure sensor by harnessing hierarchical wrinkling‐cracking architectures, including i) wrinkling‐dominant (WD) mode, ii) wrinkling and cracking‐dominant (WCD) mode, and iii) cracking‐dominant (CD) mode. The pressure sensor can exhibit distinct sensing performances for various specific applications, depending on the working mode. In a WD mode, the sensor reveals an ultrahigh sensitivity (≈20 kPa−1) and a low limit of detection (0.6 Pa), capable of sensing acoustic vibrations, subtle pulses, and tiny motions. The sensor in WCD mode can monitor the full‐range human motion from the subtle pulse to human gait during walking/jogging. Moreover, the sensor in CD mode exhibits high sensitivity (1420 MPa−1) and excellent linearity over the ultrahigh pressure range (greater than 20 MPa), and are able to detect the movement of a car and distinguish the embarkation/debarkation of an adult passenger. The underlying mechanisms for the three sensing modes have been clearly elucidated, respectively. These findings open up new possibilities to design flexible pressure sensors by harnessing wrinkling‐cracking architectures.

Detection and measurement of butterfly eyespot and spot patterns using convolutional neural networks.

Butterflies are increasingly becoming model insects where basic questions surrounding the diversity of their color patterns are being investigated. Some of these color patterns consist of simple spots and eyespots. To accelerate the pace of research surrounding these discrete and circular pattern elements we trained distinct convolutional neural networks (CNNs) for detection and measurement of butterfly spots and eyespots on digital images of butterfly wings. We compared the automatically detected and segmented spot/eyespot areas with those manually annotated. These methods were able to identify and distinguish marginal eyespots from spots, as well as distinguish these patterns from less symmetrical patches of color. In addition, the measurements of an eyespot's central area and surrounding rings were comparable with the manual measurements. These CNNs offer improvements of eyespot/spot detection and measurements relative to previous methods because it is not necessary to mathematically define the feature of interest. All that is needed is to point out the images that have those features to train the CNN.

Bionic surface diode for droplet steering

AbstractControl of droplet sliding and its interfacial behavior such as sliding resistance and friction have important applications in microfluidic and energy‐related fields. Nature provides many examples of interface‐driven droplet sliding control; yet, to date, the continuous governing of the multiphase process and precise steering of droplet sliding remain challenging. Here, directional‐dependent ultraslippery patterned surfaces with significant droplet sliding anisotropy were created by coordinating the heterogeneous wettability of the back of the dessert beetle, directional‐dependent architecture of the butterfly wing, and ultraslippery configuration of the Nepenthes alata. Analysis of the sliding resistance on typical ultraslippery patterned surfaces reveals that the directional‐dependent triple phase line (TPL) immigration on the ultraslippery patterns dominates the strong sliding anisotropy, which can be modeled using the classic Furmidge equation. In particular, the sliding anisotropy for the semicircular ultraslippery patterned surface shows threefold higher than that of natural butterfly wings due to the most significant difference in TPL immigration in two opposite directions, which enables the simultaneous handling of multiple droplets without mass loss and steering of droplet sliding/friction. This work may transform the design space for the control of multiphase interface motion and the development of new lab‐on‐a‐chip and droplet‐based microsystems.

Femtosecond laser and oscillation induced large-scale periodic micro/nanostructures on copper surfaces

Femtosecond laser micro-nano machining has become an important field for novel material and/or structure fabrications. In this paper, we propose a new and efficient laser micro-nano fabrication technique on the metal surface, in which, a femtosecond laser combined with the ultralow frequency periodic oscillation of a two-phase stepping motor was used to fabricate a large-scale 20 μm period micro/nanostructures on the copper metal surface by line scanning. The copper foils fabricated by this femtosecond laser show excellent superhydrophobic properties. Subsequently, we use femtosecond laser Z-shaped line scanning, combined with a two-phase stepping motor with ultralow frequency periodic oscillation, works on copper foil fabricate a micropores structure with a period span of 20 μm. In addition, we simulated the butterfly wing superhydro-phobic micro/nanostructures on copper plates and fabricatedsuperhydrophobic copper surfaces. This technique lays a solid foundation for the practical application of femtosecond laser lithography and is expected to be extended to other materials for new device applications.

Biomimetic microtextured surfaces to improve tribological and antibacterial behaviors of 3Y-TZP ceramics

Surface texturing has been a powerful means to improve the service performance of various engineering materials. The 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) represents the most-used ceramic oxide in restorative dentistry due to its excellent esthetic effects, good chemical stability and superior biocompatibility. However, such materials show the limited ability of tribological and antibacterial performance for dental applications. In the present work, a bio-inspired design of textured surfaces was conducted based on the microstructural analysis of butterfly wings, peacock tail feathers, and dolphin skins to improve the service performances of 3Y-TZP ceramics for dental applications. Three types of microtextures, including micro-grids, micro-feathers, and micro-grooves, were fabricated onto the 3Y-TZP ceramics using the laser ablation technique. The effects of different microtextures on the wettability, tribological and antibacterial behaviors of 3Y-TZP ceramics were studied. The results indicate that all the biomimetic microtextures can effectively improve the service performance of 3Y-TZP. Wettability acts as a decisive factor for the tribological and antibacterial performances of textured ceramic surfaces. The bio-inspired microtextured surfaces all show hydrophobic behavior, thus yielding an effective improvement of antibacterial properties for 3Y-TZP. Moreover, the micro-grids inspired by the butterfly wings basically perform the best in tribological and antibacterial tests compared with the other counterparts.