||In this thesis, we propose and demonstrate waveguide- and microresonator-based optical manipulation of polystyrene microparticles on silicon nitride (SiN) planar optical devices in an optofluidic chip. On the waveguide-based optical manipulation front, we demonstrate optical manipulation of microparticles on waveguides, directional couplers, multimode interference (MMI)-based power splitters and waveguide junctions. Using waveguide-based directional couplers, we demonstrate submicron-sized particles coupling between two coupled waveguides and finally being directed to two different output paths. On MMI-based 3dB power splitters, we demonstrate microparticle splitting functions. Various particle branching ratios can be attained through switching the input laser wavelength to tune the power ratio between the two output-ports. We also demonstrate planar optical tweezers using waveguide-junctions and tapered-waveguide junctions, in which particles can be trapped at the junction region and be successively substituted by the incoming particles. By properly designing the junctions, we demonstrate that single particles can be trapped by the waveguide-junctions, or multiple particles can be trapped at various locations near the tapered-waveguide junctions. On the microresonator-based optical manipulation front, we demonstrate tunable optical manipulation devices using microring and microdisk resonators. We demonstrate particle throughput, buffering and dropping on SiN racetrack resonator-based add-drop filters through tuning laser wavelength and choosing Q-factors. On SiN microdisk resonator-based add-drop filters, we demonstrate up to three trapping tracks and extended trapping ranges of ~3 μm for microparticles. We tune particle trajectories by tuning the laser wavelength.