Dragonfly Wing Research Articles

Nanospikes on Customized 3D‐Printed Titanium Implant Surface Inhibits Bacterial Colonization

Additive manufacturing has opened the door to patient‐tailored orthopedic implants, which can significantly minimize implant failures associated with prosthesis‐to‐bone mismatch. Success of an implant also depends on the choice of implant materials, effective osseointegration, implant quality, and the mechanical properties together with its capability to limit infection due to bacterial contamination. Herein, nanospikes are created on 3D‐printed titanium‐alloyed implant surfaces, which can kill bacteria to minimize any implant‐associated infections. For the first time, orthopedic implants with a fracture to the proximal phalanx are fabricated using selective laser melting (SLM) followed by a heat‐treatment step and the hydrothermal process. It is showed in the results that by optimizing SLM parameters, dimensionally consistent parts can be produced and tensile properties of the 3D‐printed implants can be significantly improved via a simple cyclic heat‐treatment process compared to the traditionally manufactured implants. Nanospikes similar to those present on dragonfly wings fabricated on 3D‐printed implants surface are able to kill above 90% of adhering bacteria by rupturing the membranes upon contact. These results indicate that fabrication of patient‐specific 3D‐printed implants with inherent bactericidal properties has the potential to eliminate postsurgical infections and possible implant failures.

Drop impact dynamic and directional transport on dragonfly wing surface

The ability of dragonflies to fly in the rain without being wetted by raindrops has motivated researchers to investigate the impact behavior of a drop on the superhydrophobic wings of dragonflies. This superhydrophobic surface is used as a reference for the design of directional surfaces and has attracted extensive attention owing to its wide applicability in microfluidics, self-cleaning, and other fields. In this study, the static contact angle and rebound process of a drop impacting a dragonfly wing surface are investigated experimentally, whereas the wetting pressure, Gibbs free energy, and Stokes number vs. coefficient of restitution are theoretically calculated to examine the dynamic and unidirectional transport behaviors of the drop. Results show that the initial inclination angle of the dragonfly wing is similar to the sliding angles along with the drop sliding. The water drop bounces from the bottom of the dragonfly wing to the distal position, demonstrating directional migration. The drop impacts the dragonfly wing surface, and the drop exhibits compression, recovery, and separation phases; in these three phases, the drop morphology evolves. As the Gibbs free energy and cross-sectional area evolve, the coefficient of restitution decreases as the drop continues to bounce, and the Stokes number increases.

Honeybee wings hold antibiofouling and antimicrobial clues for improved applications in health care and industries

Natural surfaces with remarkable properties and functionality have become the focus of intense research. Heretofore, the natural antimicrobial properties of insect wings have inspired research into their applications. The wings of cicadas, butterflies, dragonflies, and damselflies have evolved phenomenal anti-biofouling and antimicrobial properties. These wings are covered by periodic topography ranging from highly ordered hexagonal arrays of nanopillars to intricate "Christmas-tree" like structures with the ability to kill microbes by physically rupturing the cell membrane. In contrast, the topography of honeybee wings has received less attention. The role topography plays in antibiofouling, and antimicrobial activity of honeybee wings has never been investigated. Here, through antimicrobial and electron microscopy studies, we showed that pristine honeybee wings displayed no microbes on the wing surface. Also, the wings displayed antimicrobial properties that disrupt microbial cells and inhibit their growth. The antimicrobial activities of the wings were extremely effective at inhibiting the growth of Gram-negative bacterial cells when compared to Gram-positive bacterial cells. The fore wing was effective at inhibiting the growth of Gram-negative bacteria compared to Gram-positive samples. Electron microscopy revealed that the wings were studded with an array of rough, sharp, and pointed pillars that were distributed on both the dorsal and ventral sides, which enhanced anti-biofouling and antimicrobial effects. Our findings demonstrate the potential benefits of incorporating honeybee wings nanopatterns into the design of antibacterial nanomaterials which can be translated into countless applications in healthcare and industry.

Nature‐Inspired Biomimetic Surfaces for Controlling Bacterial Attachment and Biofilm Development

AbstractThe use of antibacterial and antifouling materials is widely being investigated to combat the increasing risk associated with bacterial infections and the evolution of drug‐resistant bacteria. Efficient antibacterial materials can be fabricated by mimicking the topography found on the surface of natural antibacterial materials. Natural materials such as the wings of cicadas and dragonflies have evolved to use the structural features on their surface to attain bactericidal properties. The nanopillars/nanospikes present on these natural materials physically damage the bacterial cells that settle on the nanostructures resulting in cell lysis and death. This article reviews the role of nanostructures found on the surface of some of these natural antibacterial and antifouling materials such as lotus leaf, cicadas and dragonflies wings, shark skin, and rose petals. These natural structures provide guidelines for the design of synthetic bio‐inspired materials. This review article also presents some novel fabrication techniques used to produce biomimetic micro‐ and nano‐structures on synthetic material surfaces. The role of size, shape, aspect ratio, and spacing between the micro/nano‐structures on the bactericidal properties is also discussed. Finally, the review is finished with the author's view on the future of the field.

Tarsal attachment structures of the biting midge Forcipomyia paludis (Diptera: Ceratopogonidae), a specialized ectoparasite of Odonata imagines

The female of the biting midge Forcipomyia paludis is a dipteran ectoparasite of West Palaearctic damselflies and dragonflies, sucking haemolymph mainly from wing veins of their hosts. This tiny midge remains firmly attached to the wings even during fast flight and aerial fight maneuvers as shown in the present paper by field studies of the large dragonfly, Cordulegaster boltonii. Since individuals of F. paludis firmly attach themselves to the challenging wing surface of their host and can successfully withstand drag and vibrations during flight, we assume that this midge species has specific microstructural adaptations on its legs for attaching to the wing surface. In our morphological study, we used scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM), to study the structure of F. paludis tarsi, as well as the micro morphology of the wing surfaces of their host. Additionally, for the first time, we were able to show attachment devices of the midges dried out in contact with the host’s surface. The spatulae of the plantar setae and especially the empodial setae, are capable of replicating nanoscale wax crystals of the super hydrophobic wing coverage of the dragonfly wing membrane, in order to increase an effective contact area and therefore adhesion. This ability requires extremely soft materials of the spatula, which seems to be rather unique even in comparison to the leg attachment devices of other dipterans and other insect taxa in general.

Wing coloration patterns in the Early Jurassic dragonflies as potential indicator of increasing predation pressure from insectivorous reptiles

Wing coloration is a very ancient feature among insects. Even the wings of the oldest known Pterygota showed transverse colored bands involved in a putative disruptive function. However, no evidence of wing coloration in the representatives of the superorder Odonatoptera is recorded before the latest Triassic. These were the only insect flying-predators until the pterosaurs began their diversification. Here we argue that the situation dramatically changed in the Early Jurassic, with the simultaneous appearance of Odonata with patterns of coloration in phylogenetically distant clades. It is especially the case in the Heterophlebiidae, a small family closely related to the Anisoptera, in which we could record no less than five different patterns of coloration in the same rather small area of North-Western Europe. At the same time and in the same area, small potentially insectivorous pterosaurs greatly diversified. The increase of the predation pressure on the Odonata is the most probable cause of the appearance of patterns of colored spots and bands on the dragonfly wings at that time. In the period between the Middle Jurassic to Early Cretaceous, the number of Odonata with spots and bands of color on wings dramatically increased, we assume in relation to the predation pressure due to an increasing diversification of insectivorous pterosaurs, but also small feathered dinosaurs and birds.

Numerical Study of Bio-Inspired Corrugated Airfoil Geometry in a Forward Flight at a Low Reynolds Number

In this study, the effects of variations in the parametric geometry on the aerodynamic efficiency and longitudinal static stability of a bio-inspired airfoil were assessed using the computational method at a low Reynolds number of 80000. The investigation aims to recognize the influence of corrugations on aerodynamic forces and moments and compare them with a non-corrugated profile having similar geometry without corrugations. Three different airfoils were chosen, the first triangular peaked corrugated is inspired from the mid-section of a dragonfly wing, the second modified simplified corrugated is a different form of the dragonfly wing section, which was modified to match the maximum thickness of the first airfoil, and the third is a non-corrugated Hybrid airfoil obtained by joining the peaks of the second airfoil. These three models were fabricated using an additive manufacturing process to undertake the experimental work in a low subsonic wind tunnel to find aerodynamic characteristics. ANSYS FLUENT solver was applied to unravel the steady, laminar, incompressible, two-dimensional, RANS equations. The tests were performed for 4 to +20 degrees angle of attack at a Reynolds number of 80,000. The result revealed that the Hybrid airfoil is suitable only for up to a 4-degree angle of attack. The modified simple corrugated airfoil produced significant aerodynamic performance at high angles of attack than the other two tested airfoils. The flow field study also showed the same results. Results are validated with experimental work and also with existing literature.

Nanoporous and nano thickness film-forming bioactive composition for biomedical applications

Unmanageable bleeding is one of the significant causes of mortality. Attaining rapid hemostasis ensures subject survivability as a first aid during combats, road accidents, surgeries that reduce mortality. Nanoporous fibers reinforced composite scaffold (NFRCS) developed by a simple hemostatic film-forming composition (HFFC) (as a continuous phase) can trigger and intensify hemostasis. NFRCS developed was based on the dragonfly wing structure's structural design. Dragonfly wing structure consists of cross-veins and longitudinal wing veins inter-connected with wing membrane to maintain the microstructural integrity. The HFFC uniformly surface coats the fibers with nano thickness film and interconnects the randomly distributed cotton gauge (Ct) (dispersed phase), resulting in the formation of a nanoporous structure. Integrating continuous and dispersed phases reduce the product cost by ten times that of marketed products. The modified NFRCS (tampon or wrist band) can be used for various biomedical applications. The in vivo studies conclude that the developed Cp NFRCS triggers and intensifies the coagulation process at the application site. The NFRCS could regulate the microenvironment and act at the cellular level due to its nanoporous structure, which resulted in better wound healing in the excision wound model.

Reconstruction of bionic models and nanomechanical behavior of dragonfly membranous wings

Dragonflies fly in flapping wing flight, bearing a variety of variable forces during flight. To comprehend and study from the biological system and then carry out technological innovation, the characteristic point cloud data of dragonfly wings were obtained and the 3D geometric models were reconstructed. The biomechanical characteristics of Costa, Radius and Postal veins of the wings were examined by a nanoindenter. It was shown that the reduced modulus and nanohardness of Radius of dragonfly forewings and hindwings are large. The maximum reduced modulus and nanohardness of Costa, Radius and Postal veins of hindwings appear at the place 0.7L of dragonfly wings. The biomechanical characteristics of dragonfly wings were researched and then the deformations and stresses of the bionic models under the uniform load were investigated. It was shown that the dragonfly wings are less deformed under the uniform load and the chief veins have stronger stability and bearing capacity. The combinations of the main veins and branch veins can improve the overall strength and load-bearing capacity of dragonfly wings. It tries to explore the structural models of imitating dragonfly wings with good load-bearing capacity and, then, were used to guide the plan and manufacturing of thin film and offer novel ideas and methods for the study of thin film.

Camouflage by counter‐brightness: the blue wings of Morpho dragonflies Zenithoptera lanei (Anisoptera: Libellulidae) match the water background

AbstractBright iridescent colours are widespread in several aquatic and terrestrial animal taxa and are usually involved in intraspecific communication and/or predator avoidance. Camouflage by iridescence may be one strategy to avoid predators when the animal exhibits bright colours that match the brightness of its surroundings. Hence, animal structural colouration may have a “brightness matching” or “counter‐brightness” function when observed against bright or glossy backgrounds. Here, we addressed the role of such counter‐brightness effect of the iridescent wings of the Morpho dragonfly Zenithoptera lanei for avoiding detection. We hypothesized that the bright reflectance of the dragonfly wings is cryptic against the bright water surface and the glossy vegetation where they naturally occur, protecting the dragonfly from visually oriented predators, deceiving prey and signalling to conspecifics when desired. We addressed whether (1) the iridescent colours of Z. lanei wings function as a visual strategy to reduce their wing detectability by brightness matching the background and (2) the detectability of wings against vegetation and water varies according to the observer. For this, we modelled how conspecifics, dipteran prey and predatory birds see the odonate wings against the vegetation of the Neotropical Savannah and against the water surface where the dragonflies perch. Our results suggest that Z. lanei dragonflies can avoid detection by predators, prey and conspecifics when perched on their natural habitats (i.e., ponds) against the bright background of the water surface. Here, we add evidence to the multifunctionality of structural colours in animals and the function of iridescence in camouflage. The bright iridescence and ultraviolet reflective nanostructures of Z. lanei wings when coupled with striking behavioural displays may provide a dynamic and safe intraspecific communication channel.

Insect and Plant Diversity in Hot-Spring Ecosystems during the Jurassic-Cretaceous Boundary from Spain (Aguilar Fm., Palencia).

Simple SummaryIn this study, we show and identify new plant and insect remains found in travertine deposits from the Jurassic-Cretaceous boundary of the Aguilar Formation (Palencia, North Spain). From this hot-spring palaeoenvironment, we have identified the presence of dragonflies of the families Cymatophlebiidae and Aktassiidae, representing the first report of these families for the Iberian Peninsula. In addition, we find a flora dominated by Bennettitales and the presence of ferns that differ from other floras of the same age and geographical area. The unusual environmental and palaeoecological conditions of this hot-spring environment are also discussed, suggesting that this niche was an “ecological oasis” for some plants and insects.Hydrothermal palaeoenvironments are very uncommon in Upper Jurassic and Lower Cretaceous deposits worldwide. We present new plant and insect remains from travertines formed during the Jurassic-Cretaceous boundary in northern Spain (Aguilar Fm., Palencia province). A total of 136 plant specimens and three insect wings were collected and studied. This entomofauna consists of dragonfly (Odonata) wings including Cymatophlebiidae and an undetermined new genus and species of Aktassiidae, representing the first report of these families for the Iberian Peninsula. The fossil flora shows different morphotypes of plants, which have been tentatively assigned to three different genera. The taphocoenosis of the flora was dominated by Bennettitales (98.5%) including cf. Pterophyllum sp., Ptilophyllum cf. acutifolium, Ptilophyllum cf. pecten, Ptilophyllum cf. pectiniformis and cf. Ptilophyllum sp., and the occasional presence of ferns (1.5%) represented by the taxon Cladophlebis cf. denticulata. The presence of the Anisoptera Cymatophlebia cf. longialata suggests a higher affinity for a Tithonian age of the studied site, and the anatomy and palaeogeographical distribution of this species suggest capacity to migrate for rather long distances. The floristic composition of the site differs remarkably from other Tithonian-Berriasian floras of the Iberian Peninsula. The presence of Odonata and the distinctive flora in (semi)arid conditions could be due to the hot-spring providing an environmental niche with constant conditions of warmth and humidity forming an ‘ecological oasis’.

Design and Numerical Simulation of Biomimetic Structures to Capture Particles in a Microchannel

The study of separating different sizes of particles through a microchannel has been an interest in recent years and the primary attention of this study is to isolate the particles to the specific outlets. The present work highly focuses on the design and numerical analysis of a microchip and the microparticles capture using special structures like corrugated dragonfly wing structure and cilia walls. The special biomimetic structured corrugated wing is taken from the cross-sectional area of the dragonfly wing and cilia structure is obtained from the epithelium terminal bronchioles to the larynx from the human body. Parametric studies were conducted on different sizes of microchip scaled and tested up in the range between 2–6 mm and the thickness was assigned as 80 µm in both dragonfly wing structure and cilia walls. The microflow channel is a low Reynolds number regime and with the help of the special structures, the flow inside the microchannel is pinched and a sinusoidal waveform pattern is observed. The pinched flow with sinusoidal waveform carries the particles downstream and induces the particles trapped in desired outlets. Fluid particle interaction (FPI) with a time-dependent solver in COMSOL Multiphysics was used to carry out the numerical study. Two particle sizes of 5 µm and 20 µm were applied, the inlet velocity of 0.52 m/s with an inflow angle of 50° was used throughout the study and it suggested that: the microchannel length of 3 mm with corrugated dragonfly wing structure had the maximum particle capture rate of 20 µm at the mainstream outlet. 80% capture rate for the microchannel length of 3 mm with corrugated dragonfly wing structure and 98% capture rate for the microchannel length of 2 mm with cilia wall structure were observed. Numerical simulation results showed that the cilia walled microchip is superior to the corrugated wing structure as the mainstream outlet can conduct most of the 20 µm particles. At the same time, the secondary outlet can laterally capture most of the 5 µm particles. This biomimetic microchip design is expected to be implemented using the PDMS MEMS process in the future.

2D numerical investigations derived from a 3D dragonfly wing captured with a high-resolution micro-CT.

BACKGROUND: Due to their corrugated profile, dragonfly wings have special aerodynamic characteristics during flying and gliding.OBJECTIVE: The aim of this study was to create a realistic 3D model of a dragonfly wing captured with a high-resolution micro-CT. To represent geometry changes in span and chord length and their aerodynamic effects, numerical investigations are carried out at different wing positions.METHODS: The forewing of a Camacinia gigantea was captured using a micro-CT. After the wing was adapted an error-free 3D model resulted. The wing was cut every 5 mm and 2D numerical analyses were conducted in Fluent 2020 R2 (ANSYS, Inc., Canonsburg, PA, USA).RESULTS: The highest lift coefficient, as well as the highest lift-to-drag ratio, resulted at 0 mm and an angle of attack (AOA) of 5. At AOAs of 10 or 15, the flow around the wing stalled and a Kármán vortex street behind the wing becomes visible.CONCLUSIONS: The velocity is higher on the upper side of the wing compared to the lower side. The pressure acts vice versa. Due to the recirculation zones that are formed in valleys of the corrugation pattern the wing resembles the form of an airfoil.

Omnidirectional / Unidirectional Antireflection-Switchable Structures Inspired by Dragonfly Wings

Randomly arranged irregular inclined conical structure-covered dragonfly wings, distinguished from periodic conical structure-covered cicada wings, are with high optical transparency for wide viewing angles. Bioinspired by the antireflective structures, we develop a colloidal lithography approach for engineering randomly arranged irregular conical structures with shape memory polymer-based tips. The structures establish a gradual refractive index transition to suppresses optical reflection in the visible spectrum. By manipulating the configuration of structure tips through applying common solvent stimulations or contact pressures under ambient conditions, the resulting unidirectional antireflection and omnidirectional antireflection performances are able to be instantaneously and reversibly switched. The dependences of structure shape, structure inclination, structure arrangement, and structure composition on the switchable antireflection capability are also systematically investigated in this study.

Structural biofilm resistance of carbon-infiltrated carbon nanotube coatings.

Periprosthetic joint infection (PJI) is a devastating complication of orthopedic implant surgeries, such as total knee and hip arthroplasties. Treatment requires additional surgeries because antibiotics have limited efficacy due to biofilm formation and resistant bacterial strains such as methicillin-resistant Staphylococcus aureus (MRSA). A non-pharmaceutical approach is needed, and examples of this are found in nature; dragonfly and cicada wings are antibacterial because of their nanopillar surface structure rather than their chemistry. Carbon-infiltrated carbon nanotube (CICNT) surfaces exhibit a similar nanopillar structure, and have been shown to facilitate osseointegration, and it is postulated that they might provide a structurally-derived resistance to bacterial proliferation and biofilm formation. The objective of this study was to test the biofilm resistance of CICNT coatings. Two types of CICNT were produced: a vertically aligned CNT forest on a silicon substrate using a layer of iron as the catalyst (CICNT-Si) and a random-oriented CNT forest on stainless steel (SS) substrate using the substrate as the catalyst (CICNT-SS). These were tested against SS and carbon controls. After 48 h in an MRSA biofilm reactor, samples demonstrated that both types of CICNT coatings significantly (p < 0.0001) reduced MRSA biofilm formation by 60%-80%. Morphologically, biofilm presence on both types of CICNT was also significantly reduced. Clinical Significance: Results suggest that a CICNT surface modification could be suitable and advantageous for medical devices susceptible to MRSA cell attachment and biofilm proliferation, particularly orthopedic implants.

Insect wing 3D printing

Insects have acquired various types of wings over their course of evolution and have become the most successful terrestrial animals. Consequently, the essence of their excellent environmental adaptability and locomotive ability should be clarified; a simple and versatile method to artificially reproduce the complex structure and various functions of these innumerable types of wings is necessary. This study presents a simple integral forming method for an insect-wing-type composite structure by 3D printing wing frames directly onto thin films. The artificial venation generation algorithm based on the centroidal Voronoi diagram, which can be observed in the wings of dragonflies, was used to design the complex mechanical properties of artificial wings. Furthermore, we implemented two representative functions found in actual insect wings: folding and coupling. The proposed crease pattern design software developed based on a beetle hindwing enables the 3D printing of foldable wings of any shape. In coupling-type wings, the forewing and hindwing are connected to form a single large wing during flight; these wings can be stored compactly by disconnecting and stacking them like cicada wings.

A Strategy towards Light-Absorbing Coatings Based on Optically Black Nanoporous Alumina with Tailored Disorder.

This work provides a conceptually new way of thinking about the light-absorbing mechanism in additive-free black porous anodic alumina (black PAA, or b-PAA) layers obtained via “burning” anodizing regime. The new insight into the controllable photonic effects in PAA allows the implementation of the optical blackening method based on the deliberate randomization of the initially well-ordered nanopore arrangement. The proposed black coloration mechanism rests solely on the destructive interference of light after its multiple scattering. Similar effects have been earlier considered for some natural or artificially created biomimetic structures (e.g., the so-called “moth eye effect”, or the coloration mechanism in the Neurothemis tullia dragonfly wings). Comprehensive analysis confirmed that the chemical composition of b-PAA has only a minor influence on the color changes and the optical density increase, and that the light-absorbing properties most likely result from the structural effects. The new functional 2D materials exhibit strong adhesion to aluminum surface, are cost-effective and suitable for application under harsh thermal or UV-light conditions. They are potentially useful for manufacturing of optical devices or heat-resistant coatings in aerospace technologies, as well as solid supports for biological filtration and fluorescence imaging.

Aqueous mechano-bactericidal action of acicular aragonite crystals

Nanoneedle structures on dragonfly and cicada wing surfaces or black silicon nanoneedles demonstrate antibacterial phenomena, namely mechano-bactericidal action. These air-exposed, mechano-bactericidal surfaces serve to destroy adherent bacteria, but their bactericidal action in the water is no precedent to report. Calcium carbonate easily accumulates on solid surfaces during long-term exposure to hard water. We expect that aragonite nanoneedles, in particular, which grow on TiO2 during the photocatalytic treatment of calcium-rich groundwater, exhibit mechano-bactericidal action against bacteria in water. Here, we showed that acicular aragonite modified on TiO2 ceramics prepared from calcium bicarbonate in mineral water by photocatalysis exhibits mechanical bactericidal activity against E. coli in water. Unmodified, calcite-modified and aragonite-modified TiO2 ceramics were exposed to water containing E. coli (in a petri dish), and their bactericidal action over time was investigated under static and agitated conditions. The surfaces of the materials were observed by scanning electron microscopy, and the live/dead bacterial cells were observed by confocal laser scanning microscopy. As a result, the synergistic bactericidal performance achieved by mechano-bactericidal action and photocatalysis was demonstrated. Aragonite itself has a high biological affinity for the human body different from the other whisker-sharpen nanomaterials, therefore, the mechano-bactericidal action of acicular aragonite in water is expected to inform the development of safe water purification systems for use in developing countries.

Effects of Pine Bark Extract on Physicochemical Properties and Biological Activity of Active Chitosan Film by Bionic Structure of Dragonfly Wing

Bionic and active films based on chitosan were developed with the bionic structure of dragonfly wings incorporating pine bark extract (PBE). Physicochemical properties of the films, including thickness, opacity, moisture content, color, mechanical properties, and water vapor permeability were measured. Antioxidant activity of the films was characterized by DPPH free radical scavenging activity. The interaction between chitosan and PBE was explored by attenuated total reflectance Fourier transform infrared spectrometry, X-ray diffraction, and differential scanning calorimetry. The results indicated that the addition of PBE gave rise to the films greater opacity, redness, and darker appearance. Compared with pure chitosan film, the thickness, opacity, mechanical properties, and oxidation resistance of the bionic chitosan–PBE film increased, and the water vapor permeability decreased. The films based on chitosan incorporated PBE and with the bionic structure of dragonfly wings can potentially be applied to food packaging.

Behavior of Pseudomonas aeruginosa strains on the nanopillar topography of dragonfly (Pantala flavescens) wing under flow conditions.

Bacterial associated infection is a threat in the medical field. Pseudomonas aeruginosa, one of the major causative agents for nosocomial infection, has developed resistance to almost all the classes of antibiotics. Recently, nanopillar-like structures were identified on the wings of insects such as cicada and dragonfly. Nanopillars both on natural surfaces and those mimicked on artificial surfaces were reported to possess bactericidal activity against a wide range of bacteria. An earlier study reported strain specific variation in the viability of P. aeruginosa on the nanopillar topography of a dragonfly wing under static condition. Here, we report the behavior of P. aeruginosa strains on a dragonfly wing under hydrodynamic conditions. The results of the study indicated that, under hydrodynamic conditions, P. aeruginosa PAO1 was attached in higher numbers to the wing surface than P. aeruginosa ATCC 9027 but killed in lower numbers. The plausible reason was identified to be the masking of nanopillars by the secreted extracellular polysaccharide. The shear rate of 1.0 s-1 showed a relatively higher bactericidal effect among the three tested shear rates.