Functions and water interaction mechanisms of micro/nanostructures on insect cuticle surfaces

Understanding the tribology and adhesion between surfaces at a wide range of length scales is essential for creating the next generation of contamination resistant and super adhesive surfaces. Adhesion and frictional control between solid-solid or solid-liquid surface contacts impact on all aspects of life and is important in a variety of industrial applications and future technologies. Many studies have investigated micro-structures (arrays) on the scale from a few to a hundred micrometres but so far researches on smaller scales have been limited. This study will focus on the contact area and wettability of surfaces on the micro/nanoscale. \n \nInsect cuticles, one of the most noteworthy naturally occurring nano-composite materials are considered a free and potentially rich source of technology 'invented' by natural selection. Many are multi-functional with efficiencies beyond that of artificially created surfaces. Insects with large wings are unable to clean themselves with their extremities. Contaminants (water and/or contaminating particles) on the wing have a negative effect on the flight capabilities of insects. Insects with a very high wing surface-body mass ratio (SM) index are more susceptible and greatly affected by contamination. A number of these insects exhibit unique structures to decrease wing contamination. \n \nRecent studies show that some of these cuticles exhibit impressive superhydrophobic properties. Little was understood about their surface characteristics on the nano-scale prior to the invention of instrumentations and techniques such as the Atomic Force Microscope (AFM) and the Scanning Electron Microscope (SEM). This study utilises the AFM to investigate the tribological properties, including adhesional properties, on a range of insect wing membranes at different length scales. The SEM has been useful to visualise and analyse the nanostructures and properties of surfaces. \n \nNew methodologies have been employed for micro and nano-scale investigation to determine the functions, functional efficiencies and potential applications of a range of micro/nanostructures recently found on the cuticle of insect wings. Interactions of natural contaminant mimicking spherical surfaces (of different size and chemistry) with insect cuticles were observed and tribological properties were measured. The project will address a number of scientific problems focusing on the control of adhesional properties between surfaces (solid-solid and solid-liquid interactions). A newly discovered water ridding mechanism due to hairs on the lacewing could lead to the creation of a true water repellent surface.