The document summarizes the author's PhD research topics which included: 1) Magneto-fluidic micro-system design for dynamic magnetic fields and local particle control. 2) Using superparamagnetic particles for biosensors to study particle motion, interactions in fluid volumes, and particle-induced momentum transfer on fluids. 3) Experiments on particle chains, twinning, and hydrodynamic interactions using microfluidic devices with magnetic fields.