Cotton thread for size-based blood cells sorting

Abstract

We proposed cotton thread as a low cost platform for fabricating size-based cell sorting microfluidic chip. The cells and beads can be wicked through 3D structures of thread via capillary forces without any external forces. However, the major mechanism of capturing cell inside of thread was mechanical entrapment inside the gaps between the fibers. Cells sorting property based on their size was tuned by using multiple threads having different twist per inch (TPI). The fabricated device has 3 different zones from the inlet to the outlet where each zone has a different TPI which means different sizes of gaps. The results showed that small beads were trapped in thread which has more TPI and smaller gaps, while bigger beads were trapped in thread with less TPI and larger gaps. For proof of concept, blood as a complex mixture of cells with wide range of size was wicked into the fabricated device. The result showed efficient separation of red blood cells, white blood cells and plasma. The capability of cotton threads as a proper material for fabrication of size based cell sorting microfluidic devices was proved with higher simplicity and efficiency.