Dynamic Drop Penetration of Horizontally Oriented Fiber Arrays.

In this experimental study, we combine drop impact into porous media and onto a single fiber to study drop impact into fiber arrays inspired by mammalian fur coats. In our 3D-printed arrays, we vary the packing density, fiber alignment, strand cross-section, and wettability. Drops impact fibers fixed at both ends, penetrating over short periods of time by momentum and laterally spreading throughout the array.

Maple samara flight is robust to morphological perturbation and united by a classic drag model.

Winged, autorotating seeds from the genus Acer, have been the subject of study for botanists and aerodynamicists for decades. Despite this attention and the relative simplicity of these winged seeds, there are still considerable gaps in our understanding of how samara dynamics are informed by morphological features. Additionally, questions remain regarding the robustness of their dynamics to morphological alterations such as mass change by moisture or area change by damage.

Water striders are impervious to raindrop collision forces and submerged by collapsing craters.

Water striders are abundant in areas with high humidity and rainfall. Raindrops can weigh more than 40 times the adult water strider and some pelagic species spend their entire lives at sea, never contacting ground. Until now, researchers have not systematically investigated the survival of water striders when impacted by raindrops.

Fur flutter in fluid flow fends off foulers.

The fouling of submerged surfaces detrimentally alters stratum properties. Inorganic and organic foulers alike attach to and accumulate on surfaces when the complex interaction between numerous variables governing attachment and colonization is favourable. Unlike naturally evolved solutions, industrial methods of repellence carry adverse environmental impacts.

Engineered Human Tissue as A New Platform for Mosquito Bite-Site Biology Investigations.

Vector-borne diseases transmitted through the bites of hematophagous arthropods, such as mosquitoes, continue to be a significant threat to human health globally. Transmission of disease by biting arthropod vectors includes interactions between (1) saliva expectorated by a vector during blood meal acquisition from a human host, (2) the transmitted vector-borne pathogens, and (3) host cells present at the skin bite site. Currently, the investigation of bite-site biology is challenged by the lack of model 3D human skin tissues for in vitro analyses.

Graded Atmospheres of Volatile Pyrethroid Overlaid on Host Cues Can Be Established and Quantified Within a Novel Flight Chamber for Mosquito Behavior Studies.

Spatial repellents are emerging as a promising approach to reduce vector-disease burden; however, the evolution of genetically resistant mosquitoes decreases repellent efficacy. The development of flight chambers to investigate spatial repellent application techniques is vital for sustainable mosquito control. We present an air-dilution chamber as a novel bioassay to study mosquito flight behavior responses to chemical gradients of the volatile, pyrethroid transfluthrin (TF).

Tracking the Body, Wing, and Leg Kinematics of Moving Mosquitoes.

In this protocol, we discuss general techniques for tracking the three-dimensional (3D) locations of the mosquito body, wings, legs, or other features of interest using videos. Tracking data must be acquired to produce detailed kinematics of moving mosquitoes. The software of focus for this protocol, DLTdv, was chosen for its widespread use and excellent support and because it is open-source.

Using Videography to Study the Biomechanics and Behavior of Freely Moving Mosquitoes.

Female mosquitoes of most species require a blood meal for egg development. When biting a human host to collect this blood meal, they can spread dangerous diseases such as malaria, yellow fever, or dengue. Researchers use videography to study many aspects of mosquito behavior, including in-flight host-seeking, takeoff, and landing behaviors, as well as probing and blood feeding, and more.

Designing a Generic Videography Experiment for Studying Mosquito Behavior.

In this protocol, we describe the basic design considerations and general method to set up a videography system to study mosquito behavior. A basic videography system to study mosquito behavior requires one or more cameras with an optical lens, camera lighting, a calibration setup, and a system to record the video data or otherwise control the camera. Here, we define two types of systems: (1) a real-time videography-based tracking system for determining the position of multiple moving (flying) mosquitoes, and (2) a high-fidelity videography system that can track the detailed movements of body, wings, and legs of a single mosquito at high spatial and temporal resolutions.

Transforming Capillary Alginate Gel (Capgel) into New 3D-Printing Biomaterial Inks.

Three-dimensional (3D) printing has great potential for creating tissues and organs to meet shortfalls in transplant supply, and biomaterial inks are key components of many such approaches. There is a need for biomaterial inks that facilitate integration, infiltration, and vascularization of targeted 3D-printed structures. This study is therefore focused on creating new biomaterial inks from self-assembled capillary alginate gel (Capgel), which possesses a unique microstructure of uniform tubular channels with tunable diameters and densities.

Fouling of mammalian hair fibres exposed to a titanium dioxide colloidal suspension.

Fouling of surfaces in prolonged contact with liquid often leads to detrimental alteration of material properties and performance. A wide range of factors which include mass transport, surface properties and surface interactions dictate whether foulants are able to adhere to a surface. Passive means of foulant rejection, such as the microscopic patterns, have been known to develop in nature.

Hydrodynamics and surface properties influence biofilm proliferation.

A biofilm is an interface-associated colloidal dispersion of bacterial cells and excreted polymers in which microorganisms find protection from their environment. Successful colonization of a surface by a bacterial community is typically a detriment to human health and property. Insight into the biofilm life-cycle provides clues on how their proliferation can be suppressed.

Predictive modelling of drop ejection from damped, dampened wings by machine learning.

The high frequency, low amplitude wing motion that mosquitoes employ to dry their wings inspires the study of drop release from millimetric, forced cantilevers. Our mimicking system, a 10-mm polytetrafluoroethylene cantilever driven through ±1 mm base amplitude at 85 Hz, displaces drops via three principal ejection modes: normal-to-cantilever ejection, sliding and pinch-off. The selection of system variables such as cantilever stiffness, drop location, drop size and wetting properties modulates the appearance of a particular ejection mode.

Landing mosquitoes bounce when engaging a substrate.

In this experimental study we film the landings of Aedes aegypti mosquitoes to characterize landing behaviors and kinetics, limitations, and the passive physiological mechanics they employ to land on a vertical surface. A typical landing involves 1-2 bounces, reducing inbound momentum by more than half before the mosquito firmly attaches to a surface. Mosquitoes initially approach landing surfaces at 0.

Drop ejection from vibrating damped, dampened wings.

The task of moisture removal from small, delicate surfaces such as sensors and flight surfaces on micro-flyers can be challenging due to remote location and small scale. Robustness is enhanced when such surfaces, of comparable scale to deposited drops, can remove deposition without external influence. At this scale, the dynamics of a solid surface responding to a mechanical input is highly-coupled to the fluid resting above.

Impacts of Free-falling Spheres on a Deep Liquid Pool with Altered Fluid and Impactor Surface Conditions.

Vertical impacts of spheres on clean water have been the subject of numerous water entry investigations characterizing cavity formation, splash crown ascension and Worthington jet stability. Here, we establish experimental protocols for examining splash dynamics when smooth free-falling spheres of varying wettability, mass, and diameter impact the free surface of a deep liquid pool modified by thin penetrable fabrics and liquid surfactants. Water entry investigations provide accessible, easily assembled and executed experiments for studying complex fluid mechanics.

Organismal aggregations exhibit fluidic behaviors: a review.

Groups of organisms such as flocks, swarms, herds, and schools form for a variety of motivations linked to survival and proliferation. Their size, locomotive domain, population, and the environmental stimuli guiding motion make challenging the study of member interactions and global behaviors. In this review, we borrow principles and analogies from fluids to describe the characteristics of organismal aggregations, which may inspire new tools for the analysis of collective motion.

Mosquitoes modulate leg dynamics at takeoff to accommodate surface roughness.

Insects perform takeoffs from a nearly unquantifiable number of surface permutations and many use their legs to initiate upward movement prior to the onset of wingbeats, including the mosquito. In this study we examine the unprovoked pre-takeoff mechanics of Aedes aegypti mosquitoes from two surfaces of contrasting roughness, one with roughness similar to polished glass and the other comparable to the human forearm. Using high-speed videography, we find mosquitos exhibit two distinct leg actions prior to takeoff, the widely observed push and a previously undocumented leg-strike, where one of the rearmost legs is raised and strikes the ground.

Void Entry by Aedes aegypti (Diptera: Culicidae) Mosquitoes Is Lower Than Would Be Expected by a Randomized Search.

Insects enter every passible space on the planet. Despite our best efforts, flying insects infiltrate slightly open windows in domiciles, automobiles, storage spaces, and more. Is this ubiquitous experience a consequence of insect abundance and probability, or are flying insects adept at detecting passageways? There remains a lack of understanding of insect effectiveness in finding passage through the voids and imperfections in physical barriers in response to attractants, a topic particularly critical to the area of insect-borne disease control.

High-speed microjets issue from bursting oil gland reservoirs of citrus fruit.

The rupture of oil gland reservoirs housed near the outer surface of the citrus exocarp is a common experience to the discerning citrus consumer and bartenders the world over. These reservoirs often rupture outwardly in response to bending the peel, which compresses the soft material surrounding the reservoirs, the albedo, increasing fluid pressure in the reservoir. Ultimately, fluid pressure exceeds the failure strength of the outermost membrane, the flavedo.

Mosquitoes actively remove drops deposited by fog and dew.

We report mosquito behaviors for removing accumulated drops of water which would otherwise increase the energy expended during takeoff and free flight. These techniques take advantage of the insect's small size and great structural strength. To dry their wings before takeoff, mosquitoes employ a flutter stroke, at double the wingbeat frequency of normal flight, generating nearly 2500 gravities of acceleration.

Wet mammals shake at tuned frequencies to dry.

In cold wet weather, mammals face hypothermia if they cannot dry themselves. By rapidly oscillating their bodies, through a process similar to shivering, furry mammals can dry themselves within seconds. We use high-speed videography and fur particle tracking to characterize the shakes of 33 animals (16 animals species and five dog breeds), ranging over four orders of magnitude in mass from mice to bears.

Mosquitoes survive raindrop collisions by virtue of their low mass.

In the study of insect flight, adaptations to complex flight conditions such as wind and rain are poorly understood. Mosquitoes thrive in areas of high humidity and rainfall, in which raindrops can weigh more than 50 times a mosquito. In this combined experimental and theoretical study, we here show that free-flying mosquitoes can survive the high-speed impact of falling raindrops.