Light-based 3D printing of mechanoluminescent living gels loaded with dinoflagellates.

Dinoflagellates, a group of marine unicellular algae, are known for the fascinating glowing effects in coastal waters. While this natural mechanoluminescent phenomenon has been explored in pressure sensors and optical transducers, technologies to shape dinoflagellate-containing materials into more complex, engineering-relevant geometries remain limited. Here, we report a three-dimensional printing strategy to manufacture complex-shaped mechanoluminescent objects using dinoflagellates embedded in biocompatible hydrogels. The growth and mechanoluminescence of the entrapped dinoflagellates were investigated by optical microscopy, emission spectroscopy, and mechanical testing of cell-laden gels. Dinoflagellate-laden gels showed strong bioluminescence when compressed at sufficiently high strain and strain rates. By incorporating the dinoflagellates into a photo-curable hydrogel, we shaped such living material into complex geometries using a widely available light-based printing technique. The ability to print dinoflagellate-laden gels into intricate shapes broadens the design space available for the creation of mechanoluminescent living objects for applications in soft robotics, self-powered sensing, and optical transduction.