Microfluidic chips for forward blood typing performed with a multichannel waveguide-mode sensor

We designed a microfluidic chip for use with an evanescent field optical sensor to conduct simultaneous measurements for ABO and Rh(D) forward blood typing. The microfluidic chip was designed to include multiplexed mixers for blood-reagent mixing and chambers for optical measurements. To achieve simple and rapid mixing in the microfluidic channels, holes containing freeze-dried reagents were employed as mixers. In addition, capillary stop valve-based multiplexing of the measurement chambers was used to effectively fill the chambers with samples without empty spaces or leaks. The five-channel microfluidic chip was designed and tested, including the mixing holes and measurement chambers. A multi-channel waveguide-mode sensor was used for optical measurement. Forward blood typing tests using human whole blood samples and anti-A, anti-B, anti-D, and Rh control reagents were conducted on the microfluidic chip. Simultaneous measurements were successfully performed using 40 μL of diluted blood samples, and ABO and Rh(D) blood types could be determined within 5 min.