Some beetles in the Namib Desert collect drinking water from fog-laden wind on their backs. We show here that these large droplets form by virtue of the insect's bumpy surface, which consists of alternating hydrophobic, wax-coated and hydrophilic, non-waxy regions. The design of this fog-collecting structure can be reproduced cheaply on a commercial scale and may find application in water-trapping tent and building coverings, for example, or in water condensers and engines.

Biomimetics is the extraction of good design from nature. One approach to optical biomimetics focuses on the use of conventional engineering methods to make direct analogues of the reflectors and anti-reflectors found in nature. However, recent collaborations between biologists, physicists, engineers, chemists and materials scientists have ventured beyond experiments that merely mimic what happens in nature, leading to a thriving new area of research involving biomimetics through cell culture. In this new approach, the nanoengineering efficiency of living cells is harnessed and natural organisms such as diatoms and viruses are used to make nanostructures that could have commercial applications.

Structures that cause colour or provide antireflection have been found in both living and extinct animals in a diversity of forms, including mirror-reflective and diffractive devices. An overview of this diversity is presented here, and behavioural and evolutionary implications are introduced.

No abstract

The photonic structures of butterfly wings are among the most anatomically diverse of all those in nature, giving rise to an unrivalled display of structural colours. These have recently become the focus of research by workers in a variety of disciplines, stimulated by their potential applications to technology (‘biomimetics’). This interest, together with the discovery of unpublished electron micrographs taken by the late Dr John Huxley (Natural History Museum, London), prompted this review of butterfly photonics in general. The current work provides a synopsis of the literature to date, covering the diversity and evolution of these optical structures and incorporating Huxley's work, which represents an important biomimetic and evolutionary database on its own. This review deals with butterfly photonic devices according to the parts of the butterfly scales on which they occur. In this way, the information is ripe for evolutionary study.

The most intense colours displayed in nature result from either multilayer reflectors or linear diffraction gratings. Here we investigate the spectacular iridescence of a spine (notoseta) from the sea mouse Aphrodita sp. (Polychaeta: Aphroditidae). The spine normally appears to be deep red in colour, but when light is incident perpendicular to the axis of the spine, different colours are seen as stripes running parallel to the axis of the spine; over a range of smaller incident angles, the complete visible spectrum is reflected with a reflectivity of 100% to the human eye. The simple structure responsible for this effect is a remarkable example of photonic engineering by a living organism.

Nature has adapted different methods for surviving dry, arid, xeric conditions. It is the focus of this comparative review to pull together the relevant information gleaned from the literature that could be utilized to design moisture harvesting devices informed by biomimetics. Most water harvesting devices in current use are not informed by nature and those that do are usually based on a biomimetic principle that has been based on one species only. This review draws on the published literature to establish a list of species (animals (vertebrates/invertebrates) and plants) whose habitat is in mainly dry or arid regions and that are known to harvest airborne moisture. Key findings have been outlined and review comments and discussion set out. Following this, surface feature convergences have been identified, namely hexagonal microstructures, groove-like and cone-like geometries. This has been coupled with direction of water flow that is driven by surface energy. As far as the authors are aware, this convergent evolution has not been brought together in this manner before. In the future this information could be translated into an engineered device for collecting water from airborne sources.

Diatoms are single‐celled microalgae with rigid walls (frustules) composed of amorphous silica. The intricate 3D microstructure of diatoms results in a high surface area formed by myriad pores and channels. The combination of the silica chemistry of the frustule coupled with the high surface area makes it particularly suitable for applications such as microscale total analysis systems. Here it is demonstrated that the diatom frustule can be chemically modified for the attachment of antibodies, and that the attached antibodies retain biological activity. These modified structures have potential applications in antibody arrays and may have use in techniques such as immunoprecipitation. These silica structures are produced in diatoms using only light and minimal nutrients and, therefore, generate an exceptionally cheap and renewable material.