Fig. 4: Commonly used label-free WGM optical resonators for biosensing.
From: Optical biosensors for diagnosing neurodegenerative diseases
a Microring resonator. Microrings are compact, chip-integrated, and compatible with microfluidic systems, but have lower sensitivity than microspheres or microtoroids. b Microsphere resonator. Microspheres have ultra-high Q factors but are difficult to integrate on chip as they are not fabricated in a planar format and c Microtoroid resonators. Microtoroids have both ultra-high-Q factors and are fabricated on a chip, opening up the potential for a high-sensitivity multiplexed assay.
