Immunomagnetic leukocyte differential in whole blood on an electronic microdevice

Leukocytes are the frontline defense mechanism of the immune system. Their composition dynamically changes as a response to a foreign body, infection, inflammation, or other malignant behavior occurring within the body. Monitoring the composition of leukocytes, namely leukocyte differential, is a crucial assay periodically performed to diagnose an infection or to assess a person's vulnerability for a health anomaly. Currently, leukocyte differential analysis is performed using hematology analyzers or flow cytometers, both of which are bulky instruments that require trained and certified personnel for operation. In this work, we demonstrate a new technique to obtain leukocyte differentials in a highly portable and integrated microfluidic chip by magnetically analyzing the CD33 expression of leukocytes. When benchmarked against conventional laboratory instruments, our technology demonstrated <5% difference on average for all subtypes. Our results show that hematology testing could be performed beyond the centralized laboratories at a low cost and ultimately provide point-of-care and at-home testing opportunities.