Patent ID: 8445192

Claim:
A method of detecting and quantifying the concentration of magnetic-responsive micro-beads in a fluid, comprising: measuring flow rate (Qm) of the fluid in at least one test micro-channel (Cm) exposed to a magnetic field gradient with flow rate (Qo) of the fluid in a calibration micro-channel (Co) not exposed to a magnetic field gradient, wherein the presence of magnetic-responsive micro-beads in the at least one test micro-channel which is exposed to the magnetic field gradient causes flocculation of the magnetic-responsive micro-beads in the fluid which reduces the flow rate of the fluid through the at least one test micro-channel, wherein both micro-channels are kept at an equal and constant pressure; calculating the ratio Qm/Qo, the difference Qo−Qm, and the ratio (Qo−Qm) p /(Qm) q , wherein p and q are derived through a calibration process, and wherein the ratios Qm/Qo and (Qo−Qm) p /(Qm) q are a proxy for the number of magnetic-responsive micro-beads in the fluid; and quantifying the concentration of magnetic-responsive micro-beads in the fluid.