Development and applications of label-free optofluidic ring resonator biosensor

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] This dissertation presents the development and applications of label-free optofluidic ring resonator (OFRR) sensor platform. The OFRR sensor naturally integrates the optical ring resonator with the capillary microfluidics by employing a micro-sized glass capillary with a thin wall. Each capillary cross section forms an optical ring resonator to support the circulating optical resonance called whispering gallery modes (WGMs) via total internal reflection (TIR). The OFRR sensor utilizes the resonance wavelength shift in response to the surrounding refractive index change as the transduction signal to monitor the biomolecular interaction on the sensor surface. The OFRR sensing principle, fabrication methods, and experimental setup design are introduced in detail. Based on the OFRR sensor platform, four different investigations are performed to demonstrate the OFRR label-free biosensing capability. A theory is developed to analyze the OFRR surface sensing sensitivity and to estimate the biomolecule surface density. Experiments are performed to demonstrate the non-specific protein binding detection, specific protein binding detection, and specific virus detection in the PBS buffer with the OFRR sensor, which characterize the OFRR sensor biosensing performance. Further study utilizes the OFRR sensor to quantify the breast cancer biomarker in clinical human serum, which marks the first application of the optical ring resonator sensor for real clinical applications.