From earthquake detection to fingerprint analysis, smart sensors turn data from our environment into decipherable and analyzable information. To further advance this field, an international team of scientists has developed an innovative opal-like material inspired by butterfly wings and peacock feathers.

As documented in a study published in Advanced Functional Materials, this low-cost crystal has the ability to respond sensitively to light, temperature, strain, or other physical and chemical stimuli. The material’s reaction to such conditions include changing color from green to blue when stretched and turning transparent when heated. Regularly interspersing a tiny amount of the “wonder-material” graphene throughout their polymer-based opals unlocked this potential in the team’s crystals.

“In this research, we were able finely distribute graphene at distances comparable to the wavelengths of visible light and showed how adding tiny amounts of the two-dimensional wonder-material leads to emerging new capabilities,” Joseph Keddie, professor of Soft Matter Physics at the University of Surrey, UK, said in a statement.

Both wearable and robust, the researchers believe their work could be used in a variety of areas. For example, in intelligent packaging, the crystals could visibly indicate whether a perishable food or drug had experienced a lively time-temperature past. Elsewhere in healthcare, the material could be used in conjunction with biomolecules to create a highly sensitive test for respiratory viruses. The crystals could even be worn by sports players to help improve their technique, as a difference in color indicates a change in the intensity of a force.  

To generate the color-changing properties of this new material, the researchers looked to nature. In some creatures, their structured microsurfaces interfere with light to produce its coloration. Peacock tail feathers, for instance, are pigmented brown but their microscopic structure causes them to also reflect blue, turquoise, and green light. Structural coloration often creates the apparent color-changing phenomena of iridescence, which the researchers' opal-like material mimicked.

Alluring and functional, the team’s material is expected to be brought to market in the near future and could be the next-generation of smart sensors.

“While these crystals are beautiful to look at, we're also very excited about the huge impact they could make to people's lives,” Dr Izabela Jurewicz, lecturer in Soft Matter Physics at the University of Surrey, concluded.