Fabrication of Chitosan Bioplastic Diffraction Gratings from Crab Shell Waste Blended with Cornstarch via Soft Lithography

Abstract

The rising demand in the seafood industry leads to significant waste, which, if not
properly disposed of, causes environmental issues. There is a need to bridge the gap
between seafood production and waste management by transforming waste into a
valuable resource. This study uses various laser sources to produce bioplastic
diffraction gratings from seafood waste and evaluate their diffraction performance. It
reports the diffraction efficiency at two laser wavelengths for chitosan bioplastic
diffraction gratings made from crab shell waste blended with starch. Chitosan was
extracted from crab shell waste through four main steps: demineralization,
deproteinization, depigmentation, and deacetylation. A chitosan-starch mixture was
prepared and then poured into a master mold for elastomer gratings, replicated from
a commercial grating. Gratings with groove densities of 600 lines/mm and 1200
lines/mm were successfully produced. Using a He-Ne laser (633 nm) with 0.8 mW
power and an Ar+ ion laser (514.5 nm) with 25 mW output power, the diffraction
efficiencies of the fabricated bioplastic gratings were measured. Results showed that
the measured diffraction angles closely matched theoretical predictions. The
diffraction power efficiencies of the bioplastic gratings were comparable to those of
polydimethylsiloxane (PDMS) grating replicas. These findings demonstrate the
compatibility of a chitosan-starch blend with soft lithography for fabricating
diffraction gratings.