Tiny sea creatures could provide inspiration for armor with built-in optical systems
A team of MIT researchers has lookedcloser than ever before at the unique shells of chitons, using X-raysto discover their secrets. The results reveal a no-compromise setupthat provides the tiny sea creatures with both protection and opticalvisibility. The findings could one day inspire man-made armor withsimilar abilities.
Turning to nature for ideas for newmaterials is nothing new. In the past, researchers have looked tofish scales, boxfish shells and even sea sponges for better bodyarmor, and we've even seen species of chiton inspiring higher-performing batteries and solar cells.
For the new MIT study, the researchersworked with a fascinating species of chiton known as Acanthopleura granulata. They have an appearance similar to the rocks amongst whichthey're usually found, and are small at only a few inches in diameter.
The creatures have developed a ceramicshell system that's not only flexible, being comprised of eightoverlapping plates, but also provides high levels of visibility, byincorporating tiny eyes throughout. Unlike the vast majority of otherliving creatures, the chiton's eyes aren't made from portein, but areinstead made up of the mineral aragonite – the same ceramic thatmakes up the rest of its shell.
Scientists have identified the littleeyes before, but the MIT study represents the first time that we'vereally delved deep into how well they work. Prior to the study, it was thought that the eyes mightbe too small to form an image.
The team used X-ray tomography to studythe architecture of the eyes, which measure less than a tenth of amillimeter in diameter. Further analysis also revealed the size,shape and orientation of the crystalline grains of the lens, whichprovided key insights into the optical performance.
Using a combination of measurements andtheoretical modelling, the researchers determined thatthe eyes are able to make out images and focus light within aphotoreceptive chamber beneath the lens. They're able to do this bothabove and below water – a necessity for the species, which lives inintertidal zones.
Not only does the research detail thefascinating nature of the chitons better than ever before, but itcould also lead to new armor that incorporates similar dualfunctionality. It's certainly early days, but the analysis could well be the first step in the process of making armor that doesn't compromise on defensive ability to provide high visibility.
"High-resolution structure andproperty studies of the chiton system provide fascinating discoveriesinto materials-level tradeoffs imposed by the disparate functinalrequirements in this case protection and vision, and are key toextracting design principles for multifunctional bio-inspired armor,"says MIT professor Christine Ortiz.
The researchers published theirfindings in the journal Science.