Control of Magnetofluidic Laser Scattering of Aqueous Magnetic Fluids

Optofluidics combines optics and fluid dynamics to integrate photonic capabilities with various fluidic platforms. However, fluidic control for photonic applications is a challenge. Magnetofluidic laser scattering (MFLS) offers a novel approach with wireless, programmable control. We report the control of MFLS of aqueous magnetic fluids for a range of applied magnetic fields. The MFLS was observed in the form of vertical streaks due to scattering from self-assembled ordered structures of magnetic nanoparticles. The time evolution of the streaks was investigated at different magnetic fields. The role of hydrodynamic parameters was determined by nanoparticle tracking analysis. Faster MFLS response was observed for magnetic fluids with higher susceptibility, higher drift velocities, smaller hydrodynamic diameters, and higher magnetic fields. These investigations are useful for wireless, programmable control of magnetic fluids relevant to optofluidic sensing and detection capabilities for microfluidic and lab-on-a-chip applications.