Silicon nitride microresonators for optical manipulation of microparticles and biosensing

Silicon photonics using microdisk and microring resonators are finding technologically important applications in the field of optofluidics and biosensing. Silicon-based microresonators that partially confine light by total internal reflection are versatile device structures which are highly wavelength-selective, micrometer-scale footprint, and readily in/out-coupled with integrated waveguides. By integrating microfluidic channels on top, microresonators can be functioned as on-chip optical tweezers to manipulate micro/nanoparticles or as biosensors. In this paper, we will highlight our recent progress in optofluidics using silicon nitride devices for on-chip optical manipulation including the experimental demonstrations of: (i) optical trapping and transporting of microparticles using racetrack microring resonators and circular microdisk resonators, (ii) microparticle transportation and buffering on double-notch-shaped microdisk resonators and (iii) microparticle trapping on hexagonal microdisk resonators. Such devices can function as the basic building blocks for "microparticle circuits" in lab-on-a-chip applications.