Biological fluid separation in microfluidic channels using flow rate control

A microfluidic device for continuous, real time blood plasma separation is introduced. This device is composed of a blood inlet, a purified plasma outlet, and a concentrated blood cell outlet. It is designed to separate blood plasma from an initial blood sample of up to 45 % hematocrit (Hct). The microfluidic device is designed and analyzed using an analogous electrical circuit, analytical and numerical studies. The numerical study results show that 27 % and 25 % of plasma volume can be separated from a total inlet blood volume of 45 % and 39 % hematocrit, respectively. The functionality of this device was demonstrated using defibrinated sheep blood (Hct=36 %). During 2 hrs. of continuous blood infusion through the device, all the blood cells traveled through the device toward the concentrated blood outlet while only the plasma flowed towards the plasma outlet without any clogging or lysis of cells. The experimentally measured plasma skimming volume was about 33 % for a 36 % inlet hematocrit. Due to the device's simple structure and control mechanism, this microdevice is expected to be used for highly efficient continuous, real time cell-free blood plasma separation device.