CAREER: Nature-Inspired, 3D-Architected Photonic Surfaces to Elucidate Structure and Disease in Fibrous Tissue

This project investigates and enables the development of a new class of nature-inspired, three-dimensionally (3D)-architected photonic surfaces, which leverage light to nondestructively map structural properties of biological specimens such as fibrous tissue onto a quantitative color response. Drawing inspiration from structural color in nature, which arises from the interaction of light with micro- and nanostructures found, e.g., on butterfly wings and beetle shells, these photonic surfaces will be rationally designed to enhance the interaction of polarized light with fibrous tissue. This basic research endeavor will enable ultrasensitive visualization of tissue microstructural properties in a single measurement without chemical stains or physical contact with the tissue – thus clearly advancing what is attainable with existing methods. It is anticipated that results of this work will lead to transformative understanding of the role of tissue microstructure in fibrotic diseases and enable more powerful and effective diagnostic tools and treatments. Beyond tissue-imaging applications, the resulting photonic surface platform provides opportunities to facilitate further societal applications ranging from display technology to information security. Education and research are well-integrated into this project. A completely new “Micro Nano Technology Research Experience” will provide local community college students with targeted preparation for technician careers, and the “MAE Bridge to Math Success” program will address the challenge of math-readiness affecting student attrition from engineering. These efforts will work to broaden and strengthen the talent pipeline to the rapidly growing semiconductor and photonics sectors. Photonic surfaces exhibit unique capabilities to generate structural color and, in cases of optical anisotropy, probe and generate varying polarization states of light. However, the design and realization of photonic surfaces for ultrasensitive mapping of small changes in polarization remains an outstanding challenge which, if addressed, would provide impactful insights to the optical and microstructural properties of weakly birefringent media, e.g. fibrous biological tissues. This CAREER project draws inspiration from highly polarization-sensitive structural color in nature, to introduce a new class of 3D-architected photonic surfaces, which are rationally designed and fabricated for the ultrasensitive, single-shot detection of weakly birefringent media. In contrast to existing intensity-based photonic surface sensors, the proposed concept leverages the vectorial nature of light to selectively enhance the weak ellipticity generated by fibrous tissue, which encodes disease-relevant microstructural information. The proposed enhancement mechanism will scale the limited range of disease-relevant ellipticities generated by fibrous tissue, across the entire attainable range, mapping each response onto a unique structural color, for their distinct differentiation and single-shot detection. Performance will be assessed with three key indicators, to quantify birefringence, ellipticity enhancement and color discrimination. The proposed photonic surfaces will be fabricated via two-photon lithography, enabling largely unexplored degrees of freedom in 3D-architected design with larger feature sizes, facilitating scalable fabrication. Subsequently, this work leverages the proposed photonic surfaces to visualize the hallmarks of fibrotic diseases, thus providing quantitative information, which is currently not readily available, and furthering our understanding of disease origin and progression. Upon successful completion, this work will establish a new paradigm where nature-inspired structural color enables ultrasensitive polarimetry, promising impact in optical sensing, materials characterization, and biomedical imaging. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.