Title: Ultra-Sensitive Whispering Gallery Mode Resonators for Photoacoustic Bio-Sensing and Imaging.

Abstract: Whispering gallery mode (WGM) microresonators are robust optical devices that have high sensitivity, high quality factors, small mode volume, and strong light-matter interaction. In my presentation, I will delve into the extensive applications of WGM microresonators, with a specific focus on their pivotal role in photoacoustic biosensing and imaging. Even though the microresonators themselves can detect very small sized particles utilizing a shift in resonance, they have to rely on evanescent field interactions with molecules on the surface, while molecules outside the range remain undetected. In this presentation we will introduce a novel approach, proposing the generation of photoacoustic signals with a pulsed laser and the detection of photoacoustic signals through the microresonator, to enable subsequent imaging or biomolecule detection. We were able to distinguish and classify three types of bacteria cells from human wound sample using the inherent microfluidic channel of microbubble resonator using this approach. Additionally, we demonstrated the versatility of this method by detecting glucose concentration in solutions. In the later part of my talk, I will present an optically transparent packaged microbubble resonator for Photoacoustic Microscopy (PAM). It’s high Q-factor enables phantom imaging with high sensitivity, offering a compact, sensitive alternative to the conventional transducer while having simple fabrication process.