Microfluidic blood-plasma separation chip using channel size filtration effect

Blood separation is an essential first step when performing blood tests for clinical diagnosis purposes. Such tests are increasingly performed using microfluidic systems due to their rapid response time, low cost and potential for automated operation. This study proposes a simple microfluidic chip comprising a straight microchannel and a grating-type plasma filtration microchannel for the automatic separation of plasma from whole human blood for further biochemical detection. In the proposed device, the whole blood sample is introduced into the microfluidic chip by means of capillary forces and the plasma is then extracted from the whole blood via a size exclusion effect induced in the plasma filtration channel. The experimental results show that the plasma is extracted with an average flow rate of 0.01 mu L/s. Moreover, the plasma collected in the outlet reservoirs has a residual cell concentration of less than 0.1%. The feasibility of the proposed device for clinical applications is demonstrated by means of creatinine detection tests with sample concentrations ranging from 0.11 to 1.78 mg/dL (10-160 mu M) and prothrombin time (PT) tests with blood samples drawn from 20 healthy individuals. The experimental results show that the device has a detection sensitivity and degree of linearity of 12.68 count/mu M and 95.38%, respectively. Moreover, the mean coagulation time in the PT tests is equal to approximately 13.3 s.