Real-Time Monitoring of Magnetic Nanoparticles Diffusion in Lateral Flow Microporous Membrane Using Spin Valve Sensors

This paper investigates real-time monitoring and detection of 10.5 nm magnetic nanoparticles (MNPs) (Fe₃O₄) flowing in a nitrocellulose (NC) membrane over two spin valve sensors. The fabricated device gives information on the concentration of MNP flowing through the NC membrane of a typical lateral flow test, and gives relevant dynamic characteristics, such as flow rate and MNP distribution on capillary-driven systems. Sensor output varies linearly with MNP concentration. Experiments show average flow rates varying from 0.2 to 0.3 mm/s depending on MNP concentration. Signal shape [ ${V}$ ( ${t}$ )] gives information on MNP spatial distribution at the particle front flowing over the sensor.