February 5, 2025 Biomedical engineers turn to Bucky Badger to show off metasurface biosensor Written By: Tom Ziemer When Filiz Yesilkoy and her University of Wisconsin-Madison graduate students set out to demonstrate the capabilities of their optical metasurfaces, they wanted to do it with a little school spirit. Filiz Yesilkoy So, the assistant professor of biomedical engineering and her team created their extremely thin (100 times thinner than a single strand of human hair) silicon membrane metasurface in the pattern of Bucky Badger, UW-Madison’s beloved mascot. By carefully engineering the holes drilled into the membrane on the Bucky pattern, they can make Bucky transmit or block light on demand. The work is a part of research outlined in a new paper published in the journal Optica. Optical metasurfaces are useful components in biochemical sensors, which can be used for disease detection and for collecting data for medical research. However, most metasurface-based biosensor technologies rely on reflection-mode optical operation, complicating the development of compact biochemical sensor platforms. In the paper, Yesilkoy’s lab demonstrated how its technology could be integrated into smaller and less complex optical systems, which would allow them to be deployed in a wider range of on-site sensing applications. Top image caption: On the left, a brightfield microscope photograph of the free-standing membrane Bucky metasurface composed of hundreds of thousands of tilted rod voids; on the right, a scanning electron micrograph image of the metasurface showing the zig-zag rod design and cavities with vertical sidewalls on a silicon membrane of tilted rods. Images courtesy Yesilkoy lab.