Nacre more commonly known as Mother of pearl is one of the most studied biomaterials due to its beauty and incredible strength. Scientists at the University of Wisconsin–Madison have trailed a radical new technique to explore what makes mother of pearl so strong; hyperspectral interference tomography. Mother of pearl is up to 3000 times more resistant to fracture than aragonite, the material which makes up the layers of nacre. It is for this reason the material is of great interest to researches. Developing an understanding of how the resulting structure is stronger than the elements that make it could enable engineers to produce stronger structures from the materials we now commonalty use.

Pupa Gilbert, electrical engineering professor Mikhail Kats, their students and collaborators have trialled this revolutionary technique to help us better understand the complex structure of mother of pearl. This non destructive process enabled the team to examine the thickness of the layers of nacre, The findings not only help us better understand the formation of the shells over the life-time of the shell fish but could potentially open up new ways of understanding climate change.

Taking optical images of nacre is much more complex than it may seem; the curved layers of the shell meant to researchers struggled to produce a good spectrum with a traditional spectrometer. It is for this reason the team turned to a new technology: hyperspectral photography. Whereby the camera can capture a full spectrum in every pixel. Using this technology in combination with advanced modelling the researchers were able to determine the thickness of each layer, pixel by pixel. The team is calling the combination of techniques hyperspectral interference tomography and hopes the process will be applicable to researching other natural transparent structures.

The examinations revealed that as the abalone shellfish ages, the layers of the shell become thinner. But, also revealed that the layered structures record the temperatures at which the layers were formed. It is hoped that with these findings researchers will be able to examine fossilised shells and develop a clearer understanding of sea temperature changes in specific regions. It was discovered that the iridescent colours we adore, are a direct result of the thickness of the layers reflecting light back to our eyes.

This furthers our understanding of the colours we are able to offer for our luxury surfaces, and builds upon the reasons why specific colourations of nacre can only be found in specific areas. Congratulations to all the team involved in this study at The University of Wisconsin-Madison. If you wish to find out more click here.