Inspired by the bionic properties of butterfly wings, scientists have recreated a complex structure previously found only in nature, which promises to open up new ways of manipulating and controlling light to create a new generation of photonic crystals.
This structure can be found in the wing scales of certain butterflies, and it can function as photonic crystals, according to a new study by researchers at the University of Birmingham. It can be used to control light in the visible spectrum, with applications in lasers, sensors and solar panels.
The new research, published in the journal Advanced Materials, shows that naturally occurring complex gyroscopic structures can be self-assembled from colloidal particles hundreds of nanometers in size.
Gyroscopes are typically curved surfaces that divide space into two interwoven channels. Each of these channels can have a network presentation of linked vertices with triple connectivity and traverse space in a particular direction (right or left). This distortion makes each network like a chiral left and right hand, whose mirror images cannot be superimposed on each other. Although this chirality gives the photonic crystal additional optical properties, it is lost when two networks of opposite chirality are brought together in the form of a double gyro structure - which can happen in some synthetic systems.
In their latest work, the researchers first proposed a single-network gyro structure constructed from colloidal spheres as a self-assembly target, and then established design principles for manufacturing such chiral crystal structures in computer simulations.
Dr Angela Demetriadou, co-author of the Advanced Materials paper, said: "This is a new and exciting way to manufacture nano-photonic media with special and tailored chiral optical properties, providing a very flexible degree of control over their properties."
Until now, research into self-assembling colloidal photonic crystals has focused on diamond structures, according to scientists at the University of Birmingham. However, the self-assembly of colloidal diamond presents a number of challenges, including the requirement to choose the cubic form over the hexagonal form for practical applications as photonic crystals in optical devices.
The new approach involves "patchy spheres," which have decorative surfaces designed to encode information about the target structure -- individual colloidal gyros. The decorative part of the surface is sticky and holds the particles together in a network structure. In addition, the work shows that the monocolloidal loops also have interesting optical properties that diamond structures lack due to their chirality.
Corresponding author Dr Dwaipayan Chakrabarti, from the School of Chemistry at the University of Birmingham, said: "To our knowledge, this is the first time that a single colloidal gyro structure has been directly self-assembled from design components. We hope that our new approach will further inspire in-depth research in the field of colloidal self-assembly, especially experimental efforts based on this exciting development."
Professor Stefano Sacanna, an expert in colloidal synthesis and self-assembly of new materials at New York University, commented: "Using cleverly patchlike spheres, their bottom-up colloidal gyroscopic structural route paves the way for a new generation of experimentally achievable photonic crystals."
Source: OFweek
