A magnetophoresis-based microfluidic detection platform under a static-fluid environment

Microfluidic cell separations and immunoassays exploit a dynamic flow environment by electrical pumps to manipulate fluids containing biomolecules and microbeads. In particular, the magnetophoresis-based microfluidics requires a delicate flow control of pumps because the flow rate affects the result sensitively. Consequently, the dynamic flow environment requiring pumps prevents the magnetophoresis-based microfluidics from popularization and miniaturization. Herein, we present a magnetophoresis-based microfluidic platform under a static-fluid environment for the detection of microbeads labeled with magnetic nanoparticles (MNPs) by simple manual operation of fluids. To overcome the residual flow caused by the manual operation, we designed a microfluidic device having a pair of microchannels; one for detecting the target and the other for a reference. The deviations due to the residual flow were corrected by comparing the difference between the mean velocities of microbeads in each microchannel where microbeads labeled with five different concentrations of MNPs could be classified. On the basis of the convenience and portability of magnetophoresis under a static-fluidic environment, this new microfluidic platform enabled semiquantitative detection of labeled particles without any complex electrical devices and could thus be used as a portable detection platform.