Designing efficient microlens arrays: lessons from Nature
Nature provides a whole host of superior multifunctional structures that can be used as inspirational systems for the design and synthesis of new, technologically important materials and devices. We review here the exceptional optical performance of microlens arrays formed by light-sensitive brittlestars, their structural and compositional features, and advantageous properties. We show that brittlestars form a nearly perfect optical device with micron-scale, lightweight, mechanically strong, aberration-free, birefringence-free, individually-addressed lenses, which offer a unique focusing effect, signal enhancement, intensity adjustment, angular selectivity, and photochromic activity. We discuss first materials fabrication strategies that were inspired by the principles involved in the formation of echinoderm calcitic structures. The biomimetic synthetic microlens arrays could be potentially used as highly tunable optical elements for a wide variety of applications.