INSPIRE Track 2: Discovery and Development of Optimized Photonic Systems for High Volume, Low Surface Area Solar Energy Harvesting: Learning from Giant Clams

University Of Pennsylvania, Philadelphia PA

Investigators

Abstract

This INSPIRE award brings together research areas traditionally supported in the Division of Integrative Organismal Systems in the Directorate for Biology, in the Materials Research Division in the Directorate for Mathematical and Physical Sciences, and the Division of Electrical, Communications and Cyber Systems in the Directorate for Engineering. Giant clams evolved an elegant system for efficiently harvesting solar energy in areas of extremely high light intensity using algae adapted for much lower light intensities. They do this by arranging algae within their tissues into vertical pillars parallel to incoming sunlight. The surface of the tissue is covered by cells called iridocytes; these function to redistribute light incident on the horizontal surface of the clam tissue evenly over the much larger vertical surfaces of the algal micropillars. The project will explore the wealth of biophysical complexity in the system to understand exactly how the clam optimizes solar energy capture. PI Sweeney will characterize the clams' evolved structural responses to changing light environment over the lifetime of a clam and over evolutionary time as observed in differences between closely related clam species. Co-PI Yang will make new materials inspired by the clam by synthesizing top-down and bottom-up design and fabrication techniques to rival biology in hierarchical structural control. The clam's design will be especially useful for utilizing inexpensive polymer photovoltaics efficiently and with low photodamage in novel devices, and for improved photobioreactor technology. The project includes internships for college students from Palau and Philadelphia to provide pre-college students with cultural knowledge of scientific career paths and concrete lab experiences. The PIs seek to turn new insights from this biophotonic symbiosis into transformative, high volume, low surface area, defect tolerant photovoltaic devices, and algal fuel culture systems. Giant clams in the genus Tridacna support microalgal symbionts with a remarkable photonic arrangement that addresses such design challenges as how to concentrate sunlight into smaller footprint devices while tolerating device imperfections and avoiding overheating and photodamage. The project integrates biological fieldwork, physical/optical modeling, and the development of at least two novel materials/devices. Evolved responses of the clam to shifts in light environment will be explored; this work will generate a matching function between light environment and iridocyte/algal pillar design that will directly inform device design. New materials will be made by synthesizing top-down and bottom-up design and fabrication techniques to rival biology in hierarchical structural control. The project will produce synthetic iridocytes which can be engineered to enhance radiance reaching any arbitrary solar energy absorber, and copy the clam's micropillar + iridocyte arrangement for a paradigm-shifting, micron-scaled photobioreactor for biofuel production. Fieldwork in Palau will allow the investigators to probe the evolution of the clam system in variable light environments.