Concentration and extraction chip of fetal nucleated red blood Cells (NRBCs) by micro gap with diaphragm for fetal DNA diagnosis from maternal blood

To realized cell-based noninvasive diagnosis of fetal DNA from maternal blood, a extraction of nucleated red blood cells (NRBCs) was performed on the micro gap chip. This chip utilized the phenomena that NRBCs were harder to pass through the micro gap due to their size and hardness of nuclei than other blood cells. By the micro gap, NRBC is trapped selectively from the blood. By employing of the air-driven diaphragm membrane at the micro gap, the gap can be expanded after trapping of NRBCs, and the trapped NRBCs were successfully recovered to outside of the chip. By this procedure, we can extract the NRBCs from the blood. The recovered yield of NRBCs and removal rate of white blood cell and red blood cell were investigated as a function of micro gap size and flow rate. In the optimal condition, more than 90% of recovery yield and more that 90% of removal rate for RBCs and WBCs were achieved. The micro gap chip is considered to be effective to extract NRBCs from blood and expected to shorten the total diagnosis time.