A novel passive microfluidic device for preprocessing whole blood for point of care diagnostics

A novel strategy to sort the cells of interest (White Blood Cells (leukocytes)) by selectively lysing the Red Blood Cells (erythrocytes) in a miniaturized microfluidic device is presented. Various methods to lyse cells on a chip exist i.e. electrical, mechanical, chemical and thermal but they need integration of electrodes, traps, reservoirs, heaters, etc which is often difficult at microscale [1 – 4]. On the other hand, FACSlyse protocol uses only osmotic pressure to lyse erythrocytes allowing further isolation of leukocytes. This motivated us to develop a novel herringbone based lyser which works on the principle of mixing whole blood with pure water in time controlled manner to lyse erythrocytes osmotically on a chip.