Contrasting Micro/Nano Architecture on Termite Wings: Two Divergent Strategies for Optimising Success of Colonisation Flights

Many termite species typically fly during or shortly after rain periods. Local precipitation will ensure water will be present when establishing a new colony after the initial flight. Here we show how different species of termite utilise two distinct and contrasting strategies for optimising the success of the colonisation flight. Nasutitermes sp. and Microcerotermes sp. fly during rain periods and adopt hydrophobic structuring/‘technologies’ on their wings to contend with a moving canvas of droplets in daylight hours. Schedorhinotermes sp. fly after rain periods (typically at night) and thus do not come into contact with mobile droplets. These termites, in contrast, display hydrophilic structuring on their wings with a small scale roughness which is not dimensionally sufficient to introduce an increase in hydrophobicity. The lack of hydrophobicity allows the termite to be hydrophilicly captured at locations where water may be present in large quantities; sufficient for the initial colonization period. The high wettability of the termite cuticle (Schedorhinotermes sp.) indicates that the membrane has a high surface energy and thus will also have strong attractions with solid particles. To investigate this the termite wings were also interacted with both artificial and natural contaminants in the form of hydrophilic silicon beads of various sizes, 4 µm C18 beads and three differently structured pollens. These were compared to the superhydrophobic surface of the planthopper (Desudaba psittacus) and a native Si wafer surface. The termite cuticle demonstrated higher adhesive interactions with all particles in comparison to those measured on the plant hopper

Radiation patterning of P(tBuMA-co-MMA) thin films for biosensor applications: characterization by scanning probe microscopy

Poly-tert-butyl methacrylate-co-methyl methacrylate thin film surfaces were patterned and subjected to surface treatment by UV radiation and NaOH exposure, in order to tailor hydrophilic/hydrophobic conditions. The polymer has potential applications as elements of advanced biosensors and other bio-active devices. The topographies and surface chemistries on the micro- and meso-scales of thin films have been characterized by scanning force microscopy operated in the normal contact imaging mode as well as the lateral force and force versus distance modes

A Dual Layer Hair Array of the Brown Lacewing: Repelling Water at Different Length Scales

Additional weight due to contamination (water and/or contaminating particles) can potentially have a detrimental effect on the flight capabilities of large winged insects such as butterflies and dragonflies. Insects where the wing surface area-body mass ratio is very high will be even more susceptible to these effects. Water droplets tend to move spontaneously off the wing surface of these insects. In the case of the brown lacewing, the drops effectively encounter a dual bed of hair springs with a topographical structure which aids in the hairs resisting penetration into water bodies. In this article, we demonstrate experimentally how this protective defense system employed by the brown lacewing (Micromus tasmaniae) aids in resisting contamination from water and how the micro- and nanostructures found on these hairs are responsible for quickly shedding water from the wing which demonstrates an active liquid-repelling surface

Actin adsorbed on HOPG and mica substrates : characterization and manipulation by atomic force microscopy

We report on the fabrication of nanostructures built of actin using the Atomic Force Microscopy and molecularly organised substrata, i.e. HOPG and mica. We obtained both ‘paracrystalline rafts’ of actin adsorbed onto hydrophobic HOPG, as well as selective adsorption with nano-scale definition obtained on mica by taking advantage of the propensity of actin to seek sites of lowest energy configuration at interfaces. In the latter mode, we obtained circular patterns of 100-500 nm diameter. Filamentary structures on a hydrophobic substrate form paracrystalline rafts that can readily be manipulated on the nano-scale, while adsorption on a hydrophilic surface suggests that tailored interfaces will impose structural predictability

Actin nanotracks for hybrid nanodevices based on linear protein molecular motors

Hybrid nano-devices based on linear protein molecular motors working on micro/nano-engineered surfaces that operate in a 'cargo architecture', i.e. motor functionalized nano-objects running on nano-tracks, offer more opportunities than the inverse "sliding architecture" because it fully uses the information regarding directionality which is encoded in tracks, i.e. actin filaments or microtubules. However, this architecture requires the development of techniques for nanolithography with actin filaments (or microtubules) based on molecular self-assembly on engineered surfaces. The present contribution reports on the progress we have made regarding the building of actin nanostructures that would preserve the inherent information over extended micro-sized areas

Interactions of poly(amino acids) in aqueous solution with charged model surfaces: analysis by colloidal probe

No abstract available

Surface topography and surface chemistry of radiation-patterned P(tBuMA)

Poly-(tert-butyl methacrylate) (P(tBuMA)) thin-film surfaces were patterned by UV radiation at doses in the range 10-100 mJ cm-2, in order to induce laterally differentiated surface chemistry with µm resolution. The most likely pathway for the radiation chemistry predicts a transition from hydrophobicity to hydrophilicity. Outcomes of analysis by atomic force microscopy under air ambient conditions were consistent with that prediction. Topographic and lateral force imaging, in combination with friction loop analysis, revealed shrinkage and increased friction arising from exposure. Force versus distance analysis revealed greater adhesion in hydrophilic regions, due to greater meniscus force acting on the tip. The thickness of adsorbed moisture, increased by a factor of 2.5 from ca 0.8 nm for the unirradiated surface, as a result of greater hydrophilicity induced by radiation. The latter observation shows that the increased friction was due principally to the greater normal force on the tip from an additional meniscus force

Nanolithography of polymer surfaces by atomic force microscopy

Laterally differentiated chemistry and structure of surfaces are commonly employed in a variety of devices/components (e.g., biosensors, array devices). At present such devices are based on macroscopic technologies. Future applications of differentiated surfaces are expected to place considerable demands on down-sizing technologies, i.e. enable meso/nanoscopic manipulation. The atomic force microscope (AFM) has emerged as an ideal platform for manipulation, visualization and characterisation of surface structures on the nano-scale1-14. Controlled AFM-based tip-induced lithography on P(tBuMA) thin film polymer surfaces has been obtained, at line widths down to tens of nanometres and depths in the sub-nanometre range. Parameters giving rise to production of nano-structures can in principle be defined for different polymers (lever-induced out-of-plane loading and in-plane shear forces, linear tip speed, tip shape and chemistry, polymer surface chemistry and mechanical properties). However, those sets of parameters, and their relationship to lithographic outcomes, cannot be derived from the currently accepted models for wear between macroscopic objects in sliding contact