2021-10-182021-10-182021-082021-07-26August 202Zhao, Xuan. "Near-Field Sensing of Single Cell Activities Using Visible-Range Micro-Ring Resonators." (2021) Master’s Thesis, Rice University. <a href="https://hdl.handle.net/1911/111551">https://hdl.handle.net/1911/111551</a>.https://hdl.handle.net/1911/111551The development of optogenetic actuators as well as genetically encoded fluorescent indicators provide powerful resources to advance the study of the brain. Moreover, optogenetic control combined with optical recording has a huge potential on achieving all-optical-based, high-speed closed-loop neuromodulations with cellular and biomolecular specificity, which can be critical to many areas of studies, such as brain dynamics, reverse-engineering of neural circuits, and treatments for neurological diseases. However, achieving all-optical interrogation requires optical tools and sensors with high spatiotemporal control and resolution, yet traditional optical setups suffer from light penetration depth and their large form factors, which limit their extent of reach as well as the SNR. In this thesis, we propose to develop a high-fidelity biohybrid sensor based on optical measurements of visible-range micro-ring resonators (MRRs). Through FDTD simulations, we show that the designed MRR is sufficiently sensitive to detect action potentials of an individual cell via absorption measurements. For proof-of-principle validation, we fabricate the MRR sensors, and design and construct a customized biophotonic experimental platform to characterize the MRR sensors and perform in-vitro experiments. Thanks to integrated photonics, the sensitivity and scalability of this geometry could potentially enable optical recording of many individual cells across large physical areas. The combination of our proposed MRR sensors with the existing integrated photonic optogenetic stimulators could provide a possible solution to the future’s miniaturized and scalable neural interface for all-optical-based, closed-loop neuromodulation.application/pdfengCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.nanophotonic sensingneuroengineeringThesis2021-10-18