Session: Rising Stars of Mechanical Engineering Celebration & Showcase

Paper Number: 149681

149681 - Ultra-Sensitive, Selective, and Label-Free Optical Sensing for Fundamental Science, Environmental Monitoring, and Translational Medicine 

Whispering gallery mode microtoroid optical resonators, when combined with frequency locking, balanced detection, and data processing techniques, are capable of label-free single molecule detection at zeptomolar concentrations in under 30 seconds. We have developed such a system called FLOWER (frequency locked optical whispering evanescent resonator).  Ultra-high-quality resonators such as microtoroid optical resonators are capable of storing light for hundreds of nanoseconds, thus enabling enhanced interaction of light with matter and high signal-to-noise biochemical detection. Here, we present the principles of FLOWER, including noise analysis, and how, at such low concentrations, we can achieve sensing times on the order of seconds. In addition, we present our ongoing work on using FLOWER for fundamental studies on taste, and a variety of applications including drug screening, medical diagnostics for ovarian cancer, and chemical threat sensing. We validate our technology against existing approaches and perform detection in complex biological fluids. We also present our next generation sensing platforms, including how we combine FLOWER with frequency comb technology to enable simultaneous detection and absorption spectroscopy, our work on high sensitivity photothermal spectroscopy, and our work towards a robust, portable, translatable device. Finally, we describe work toward an optical "nose" inspired by the olfactory capabilities of animals. Animals' noses can distinguish among many thousands of different chemicals. Smell plays a critical role in chemical communication, sensing danger, and navigation. Thus, a biomimetic sensor based on an olfactory system would have tremendous benefits. Our biomimetic sensor seeks to automate and enhance tasks currently performed by animals and humans with superior sensitivity and selectivity. Unlike traditional bioinspired electronic noses (e-noses) which suffer from stability and response speed issues, our approach integrates engineered olfactory receptors with whispering gallery mode microtoroid resonators. By leveraging the high sensitivity of whispering gallery mode resonators and employing computational design of olfactory receptors, our optical nose aims to detect extremely low concentrations of biological and chemical targets relevant to diverse diseases, environmental monitoring, and security threats. This interdisciplinary approach merges computational molecular design, synthetic biology, specialized surface chemistry, and photonic advancements to significantly advance biochemical sensing capabilities. Furthermore, our initiative includes an educational outreach component featuring a do-it-yourself (DIY) refractometer kit. This kit introduces middle and high-school students to optical engineering concepts, offering lessons on optics and practical applications in food and water quality testing. By democratizing scientific knowledge, we aim to foster a sustained STEM pipeline and inspire future generations of scientists and engineers.

Presenting Author: Judith Su University of Arizona

Presenting Author Biography: Judith Su is an Associate Professor in Biomedical Engineering and an Associate Professor in Optical Sciences at the University of Arizona. Judith received her B.S. and M.S. from MIT in Mechanical Engineering and her Ph.D. from Caltech in Biochemistry & Molecular Biophysics. Her lab focuses on building next generation optical sensing platforms and, with these sensors, collaborating with top researchers to solve the most significant and pressing problems in science, medicine, and issues confronting society. She is a recipient of an NSF CAREER award, an NIH R35 Outstanding Investigator Award, an American Society of Laser Surgery and Medicine Young Investigator Award, the Journal of Physics Photonics 2023 Early Career Award, and is one of the 2024 Photonics100 which recognizes the industry’s most innovative people. She was a Siegman International School on Lasers Lecturer and a Scialog: Chemical Machinery of the Cell Fellow. She was on the Board of Scientific Counselors for the National Institute for Occupational Safety and Health (NIOSH). She gave a keynote talk at SPIE Photonics West 2022 and was the general co-chair for Optica’s 2023 Advanced Photonics Congress, Integrated Photonics Research (IPR) Conference in Busan, Korea. She is serving again as IPR’s co-general chair in 2024 in Quebec City, Canada.

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