Researchers have developed a process to turn crab shells into a bioplastic that can be used to make optical components known as diffraction gratings. The resulting lightweight, inexpensive gratings are biodegradable and could enable portable spectrometers that are also disposable. "The Philippines is known for delicious seafood, but this industry is also a source of large amounts of solid waste such as discarded crab shells," said research team leader Raphael A. Guerrero, from Ateneo de Manila University in the Philippines. "We wanted to find an alternative use for crab shell waste, and decided to find out if chitosan from crab shells could be used as a biodegradable replacement for silicone, which we had previously used in our lab to make diffraction gratings." 

In Applied Optics, the researchers showed that the chitosan-based bioplastic can be used to make diffraction gratings that work just like commercially available ones. "Gratings made of chitosan are biodegradable and environmentally friendly while also being very inexpensive since crab shells are generally considered waste," said Guerrero. "By showing that useful optical components can be made from materials typically considered waste, we hope to help improve sustainability in optical manufacturing and reduce the amount of seafood waste that requires disposal." ......