High-gradient magnetophoretic bead trapping for enhanced electrochemical sensing and particle manipulation.

Magnetic particles are routinely used in many biochemical techniques. As such, the manipulation of these particles is of paramount importance for proper detection and assay preparation. This paper describes a magnetic manipulation and detection paradigm that allows sensing and handling highly sensitive magnetic bead-based assays. The simple manufacturing process presented in this manuscript employs a CNC machining technique and an iron microparticle-doped PDMS (Fe-PDMS) compound to create magnetic microstructures that enhance magnetic forces for magnetic bead confinement. Said confinement, generates increases in local concentrations at the detection site. Higher local concentrations increase the magnitude of the detection signal, leading to higher assay sensitivity and lower limit of detection (LOD). Furthermore, we demonstrate this characteristic signal enhancement in both fluorescence and electrochemical detection techniques. We expect this new technique to allow users to design fully integrated magnetic bead-based microfluidic devices with the goal of preventing sample losses and enhancing signal magnitudes in biological experiments and assays.