2023-10-23 10:55:49
These soft, vivid materials glow in response to mechanical stresses, such as compression, stretching or twisting. – UC SAN DIEGO JACOBS SCHOOL OF ENGINEERING
MADRID, 23 Oct. (EUROPA PRESS) –
New materials conceived at UC San Diego glow in response to mechanical stresses, such as compression, stretching or twisting. They obtain their luminescence from unicellular algae.
The work, inspired by bioluminescent waves observed during red tide events on San Diego beaches, is published in Science Advances.
“An interesting feature of these materials is their inherent simplicity: They require no electronics or external power source,” said the study’s senior author, Shengqiang Cai, a professor of mechanical and aerospace engineering at UC San Diego’s Jacobs School of Engineering. “We demonstrate how we can harness the power of nature to directly convert mechanical stimuli into light emission.“.
The main ingredients of bioluminescent materials are dinoflagellates and an algae-based polymer called alginate. These elements were mixed to form a solution, which was then processed with a 3D printer to create a wide range of shapes, such as grids, spirals, spider webs, balls, blocks and pyramid-shaped structures. The 3D printed structures were then cured as a final step.
When materials are subjected to compression, stretching or twisting, the dinoflagellates they contain respond by emitting light. This response mimics what happens in the ocean, when dinoflagellates produce flashes of light as part of a defense strategy against predators. In tests, the materials glowed when researchers pressed them and traced patterns on their surface. The materials were even sensitive enough to glow under the weight of a foam ball rolling across their surface..
The higher the voltage applied, the brighter the shine. The researchers were able to quantify this behavior and developed a mathematical model that can predict the intensity of the glow based on the magnitude of the applied mechanical stress.
The researchers also demonstrated techniques to make these materials strong under various experimental conditions. To strengthen the materials so that they can withstand substantial mechanical loads, a second polymer, polyethylene glycol diacrylate, was added to the original mixture. Additionally, coating the materials with an elastic, rubber-like polymer called Ecoflex provided protection in acidic and basic solutions. With this protective layer, The materials could even be stored in seawater for up to five months without losing their shape or bioluminescent properties.
Another beneficial feature of these materials is their minimal maintenance requirements. To continue functioning, dinoflagellates within materials need periodic cycles of light and dark. During the light phase, they carry out photosynthesis to produce food and energy, which are then used in the dark phase to emit light when mechanical stress is applied to them. This behavior reflects the natural processes that come into play when dinoflagellates trigger bioluminescence in the ocean during red tide events.
“This current work demonstrates a simple method for combining living organisms with non-living components to make new materials that are self-sustaining and responsive to fundamental mechanical stimuli found in nature“said the study’s first author, Chenghai Li, a mechanical and aerospace engineer and doctoral candidate in Cai’s lab.
The researchers imagine that these materials could be used as mechanical sensors to measure pressure, strain, or stress. Other potential applications include soft robotics and biomedical devices that use light signals to perform treatments or controlled drug release.
However, much work remains to be done before these applications can be realized. Researchers are working to continue improving and optimizing the materials.
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