Integrated optical sensors and nano-structures for biomedical diagnosis applications

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This research focuses on developing novel high performance label-free optical index of refraction sensors based on Photonic Crystal Slab (PCS) nanostructures that will improve the sensing detection limit, and apply optical imaging of nano-structured surfaces for nano-spectroscopy of molecules and evaluating molecular interactions within a confined volume. Nanostructures have proven to be extremely useful for biosensing in the past decade using techniques such as Fluorescence, Index of refraction changes, Raman spectroscopy and Plasmonic effects. Nevertheless, their broad use is limited by challenges in repeatability, their detection limit and their high sensitivity to external environment fluctuations (such as temperature, vibrations, liquid handling). In this proposal we seek to 1) increase sensing detection limit with new PCS designs and self-referencing techniques; 2) develop imaging architectures in PCS biosensors to investigate many molecular interactions in parallel. In our designs, we will focus on label-free techniques where binding of a molecule to a surface or molecular interactions result in localized mass concentration and index of refraction changes that can be detected through spectral shifts or intensity changes in an image. We will explore new device physics opportunities in breaking structural and angular symmetry and introducing hybrid metal/dielectric structures for field re-shaping in close proximity (< 100 nm) of the sensing surfaces as well as evaluate many molecular interrogations in parallel, using optical imaging techniques. The proposed program is accompanied by our collaboration efforts with bio-chemists and seeks to accomplish breakthroughs in both fundamental and applied research in nano-photonics and bio-detection and translate our findings to practical bio-sensor schemes. In the past years, our group has acquired skills in developing new biosensors designs and building on our past work and strong collaborations with Toronto local hospitals and Stanford University we have everything in place to bring this proposal to success. We believe that improved detection limit and stability (reduced environmental effect on measurements) will greatly increase the use and performances of biosensors for bio-molecule detection with and without labeling agents.The success of this project will have significant impacts on a broad audience – from cell biologists seeking to study physiological processes in real-time, to diagnosticians searching for rapid, label-free, portable assays. Example end-user applications include low cost, sensitive and environmentally stable blood and urine diagnostic tests, evaluating viral infections quickly and studying molecular interactions within a confined volume that allows parallel evaluation of many drug targets for a disease. Canadian patients will have access to accurate, sensitive and affordable diagnostic tools that can be used in many local clinics and not only in large hospital settings. Furthermore, the research proposed will thrive from cross-disciplinary interaction between the trainees, members of our lab and collaborations with other labs at the University of Toronto and in Canada.