3D microfluidic analytical device on a single thread for smart point-of-care blood typing

This paper introduces the concept of three-dimensional microfluidic single thread-based analytical devices (3D-μSTADs) for accurate point-of-care blood typing. The 3D-μSTADs were fabricated using a double-sided imprinting process, where hydrophobic PDMS materials were pressed onto a hydrophilic cotton thread and heated for curing. By harnessing the intricate structures of the cotton fibers in vertical channels, 3D-μSTADs can effectively filter agglutinated red blood cells (RBCs) and allow free RBCs to continuously flow, resulting in a significant difference in wicking behavior between free and agglutinated RBCs. This difference eliminated the traditional requirement for a buffer solution and allowed direct observation of blood typing results based on whether blood flow reached the intended area. In our experiments, the proposed 3D-μSTADs successfully classified 105 ABO and RhD blood samples. To minimize environmental light interference and reduce potential personal bias, we designed a 3D printing blood-typing chip (3D-μThread-BT chip), which integrated the 3D-μSTADs with smartphone scanning for automated result readout. With color algorithmic modifications, the chip can ensure accurate, on-site blood typing across varying ambient light intensities by simply scanning the blood flow results. We believe that this work will inspire further research into 3D microfluidic single thread-based devices, unlocking their potential for a wide range of applications.