A microfluidic chip for capturing, imaging and counting CD3^sup +^ T-lymphocytes and CD19^sup +^ B-lymphocytes from whole blood

We have designed and evaluated a simple and practical system for CD3+ (T-lymphocyte) and CD19+ (B-lymphocyte) cell counting on-chip using a PDMS microfluidic chip which captures these cells using a pillarbased filtration technique. Conventional pillar-based or membrane-based cell separation methods suffer from the problem of cell clogging, thereby reducing the separating and capturing efficiency of the device. To address these issues, we proposed a unique and simple design of a microfluidic chip with an escape route at the pillar-based cell filtration area in the chip which prevents cell clogging. Currently, the diagnosis, monitoring and treatment of immunodeficiency disorder require quantifying the leukocyte population, especially T-lymphocytes and Blymphocytes, in whole blood. We evaluated the performance of our microfluidic chip by obtaining the ratio of T-lymphocytes and Blymphocytes from whole blood and compared the results to those obtained using a flow cytometer. We confirmed that the cell capture area of the microfluidic chip remains clog-free. We achieved 99.8% efficiency in capturing leukocytes using the microfluidic chip, and the ratio of CD3+ and CD19+ had a coefficient of r = 0.9876 and a coefficient of variation (CV) of 2.77%, from 1 μL of whole blood sample.