Close

Search

Search Menu
Photonics Media Photonics Marketplace Photonics Spectra BioPhotonics EuroPhotonics Vision Spectra Photonics Showcase Photonics ProdSpec Photonics Handbook

Mechanochromic, thermochromic, piezochromic … or just pretty

Facebook Twitter LinkedIn Email Comments
POLINA POTOCHEVSKA, EDITORIAL INTERN [email protected]

It took nature millions of years to develop the tiny scales that give butterfly wings — which are themselves transparent — their intense coloration. Like peacock feathers, they derive their signature hues from structures rather than pigments.

A different sort of butterfly effect is evident in the development of nanocrystals that produce intense, changeable colors from tiny structures rather than pigments. Courtesy of the University of Surrey.


A different sort of butterfly effect is evident in the development of nanocrystals that produce intense, changeable colors from tiny structures rather than pigments. Courtesy of the University of Surrey.

Now, a team led by scientists at the University of Surrey and the University of Sussex in England has borrowed from nature’s bag of tricks to develop a flexible photonic crystal that can not only display brilliant colors, but also reversibly change them.

The photonic crystals contain graphene — a one-atom-thick crystalline form of carbon — and are created using evaporation-driven self-assembly of soft polymer colloids, according to a paper published in Advanced Functional Materials titled “Mechanochromic and Thermochromic Sensors Based on Graphene Infused Polymer Opals.”

The title refers to the feature that makes the opalescent crystals more than a pretty bauble. Their color can respond to light, temperature, strain, or other physical and chemical stimuli, which offers interesting options for cost-effective, robust visual sensors. The sensors appear green under natural light but shift to blue when stretched. They can even turn transparent at higher temperatures. Their crystals act as shape-memory polymers, allowing them to memorize and recover their original shape and color.

The researchers added graphene into a colloidal crystal lattice to form photonic crystals with angle-dependent structural color and a reversible stopband. These unique features make the crystals good candidates for a variety of visual sensing applications.

Their sensitivity to thermal changes offers a visual indicator when perishables, such as food or pharmaceuticals, have experienced undesirable time-temperature histories, for example. Their pressure-responsive shape-memory characteristics also enable them to precisely reveal fingerprints, offering new options for biometric and anti-counterfeiting applications. If functionalized with biomolecules, the crystals could enable the creation of highly sensitive point-of-care testing devices for respiratory viruses, offering inexpensive, reliable, and user-friendly biosensing systems.

The crystals’ color can respond to light, temperature, strain or other physical and chemical stimuli, which offers interesting options for cost-effective, robust visual sensors.
The list of possible applications goes on. As Izabela Jurewicz, a lecturer in soft matter physics at Surrey, said: “While these crystals are beautiful to look at, we’re also very excited about the huge impact they could make to people’s lives.”

It’s clear that nature can serve as a powerful inspiration to scientists, and the functionality of nature’s colorful creatures and materials can be translated into new and exciting technologies today.
 

Photonics Spectra
Oct 2020
Lighter SidematerialsSensors & DetectorsUniversity of SurreyUniversity of Sussexphotonic crystalgraphene

Comments
back to top
Facebook Twitter Instagram LinkedIn YouTube RSS
©2020 Photonics Media, 100 West St., Pittsfield, MA, 01201 USA, [email protected]

Photonics Media, Laurin Publishing
x Subscribe to Photonics Spectra magazine - FREE!
We use cookies to improve user experience and analyze our website traffic as stated in our Privacy Policy. By using this website, you agree to the use of cookies unless you have disabled them.