Biochip technology applied to an automated ABO compatibility test at the patient bedside

In the field of blood transfusion, there is a need to improve the bedside pre-transfusion ABO compatibility test. In France, this test is mandatory for each red cell concentrates transfusion. It is performed manually and serious transfusion accidents still occur, principally due to human errors. Therefore, an automated ABO compatibility test is required. Works concerning objective interpretation of ABO compatibility test have been reported but the proposed techniques cannot be easily translated to the patient's bedside. We propose a prototype device which demonstrates the easy use of biochip technology to perform this test: it contains a fluidic system, biochips (two to test the patient and two to test the red cell concentrates) and an optical absorbance detection module. When blood is applied to the biochips, red blood cells are trapped onto the surface if antigens and antibodies are complementary (positive chips). If they are not complementary, very little red blood cells are adsorbed (negative chips). Percentages of surface covered with red blood cells in negative biochips are 2% ± 2 (red cell concentrates) and 1% ± 1 (whole blood). This proves that the fluidic configuration leads to an optimum control of fluids flows with little retention of red blood cells in the circuitry. These percentages increase to 96% ± 3 and 82% ± 8 for red cell concentrates and whole blood respectively. This demonstrates a strong and specific immunocapture of red blood cells on positive chips. Furthermore, optical detection proves to be efficient at critical red blood cells concentrations (108 C/mL) and absorbance strongly correlates to the percentage of red blood cells captured by antibodies.