Selective capture of a specific cell type from mixed leucocytes in an electrode-integrated microfluidic device

We describe a microfluidic method to selectively capture a type of leucocytes (neutrophils or eosinophils) from a suspension of mixed leucocytes in a specific region of a microchannel whose upper wall is equipped with an array of microband electrodes. One of the microelectrodes is used for locally electrogenerating hypobromous acid (HBrO) that renders the opposite face of the channel protein-adsorptive. Since the patterned layer of poly(ethylene glycol)dimethacrylate (PEGDM), impervious to HBrO, is previously introduced at the channel bottom, the region of protein adsorption can be precisely defined even in the presence of fluid-flow. After capture antibody was immobilized on the treated region, an AC voltage (1 MHz, 20 V_pp) was applied to the microelectrode array for negative dielectrophoresis (DEP) to quickly concentrate cells from the flowing cell suspension. By immobilizing neutrophil- or eosinophil-specific antibodies onto the created region, we demonstrated that the corresponding leucocyte type can be captured from the concentrated leucocytes.