Sweeney, an assistant professor of physics in the Penn School of Arts and Sciences, and her collaborator Shu Yang, a professor of materials science and engineering in the School of Engineering and Applied Science, refer to the clams as “solar transformers” because they are capable of absorbing bright sunlight at a very high rate and scattering it over a large surface area. When the light is distributed evenly among the thick layer of algae living inside the clam, the algae converts the light into energy.
“What those sparkly cells are doing,” Sweeney says, “is causing light to propagate very deeply into the clam tissue and spread out.”
Yang and Ph.D. student Hye-Na Kim devised a method of synthesizing nanoparticles and adding them to an emulsion — a mixture of water, oil, and soapy molecules called surfactants — to form microbeads mimicking the giant clam cells responsible for solar transforming. Their paper has been published in Advanced Materials.
Sweeney compared the process to making a salad vinaigrette. “If you take nanoparticles, add them to the oil-water emulsion and shake it at the right speed, the droplet size can be controlled,” she explained.
After doing an optical characterization of the beads, the researchers found that they function very similarly to the clam cells.
“It’s very efficient, and it’s very difficult to achieve,” Yang says.
The researchers’ next step is to try to mimic the organization of the algae within the clams by getting algae to grow in gel pillars. Once achieve this, they hope to marry their artificial iridocytes and the algae and measure the system to see if it can produce fuel to the same high efficiencies as the giant clam.
“It’s exciting to see the clever, non-intuitive ways that life has come up with to solve problems,” Sweeney says. “It’s figuring out these really clever design strategies that you wouldn’t get to from a top-down human approach.”
This research was supported by a grant from the National Science Foundation.
Photo: Irodycites, the "sparkly" cells on the surface of clams, cause light to propagate very deeply into the clam tissue and spread out. When the light is distributed evenly among the thick layer of algae living inside the clam, the algae quickly converts the light into energy.
