Recent developments in agar-based optical devices

Biocompatible optical devices are breakthrough illumination, imaging, and biomedical sensing technologies. Despite the noteworthy developments in silk, cellulose, and hydrogel-based optics, such approaches rely on expensive precursors and intricate fabrication. Therefore, agar extracted from red algae emerges as a promising biodegradable alternative as an edible, low-cost, and renewable material. This paper overviews the state-of-the-art of agar-based optical devices. Firstly, we revisit this phycocolloid’s fundamentals and highlight its appealing mechanical, optical, and electrical characteristics. Subsequently, we summarize the available agar elements, slab waveguides, and optical fibers. Lastly, we discuss their advantages and challenges by envisaging opportunities for future developments and applications.