LAUSR

Blood is the most intensely studied human biofluid and is used as the main indicator (so-called "gold standard") of the health status of the individual. Blood is also a very complex fluid, containing a multiplicity of components, including cells and cell fragments (red and white blood cells, platelets), proteins, and many other organic molecules. Laboratory-based blood analysis is a standard procedure that provides a wealth of information about the concentration of key components and enables medical personnel to establish diagnoses and treatments. To date, options for point-of-care (POC) or point-of-use (POU) blood analysis are limited and very low-cost options even more so. One analytical platform that contains the promise to fill this need utilizes paper-based microfluidic devices. This is a research area that has exhibited significant growth in the past few years, primarily because of its simplicity, fundamental low cost, and versatility. This article reviews the basic properties of blood, how these properties are utilized in a variety of diagnostic devices and illustrates selected diagnostic assays performed using paper microfluidics. While much work is being carried on the use of plasma and serum for diagnostics, the article focuses on whole blood since it is the most likely format for POC/POU diagnostics, with the exception of those cases where a built-in plasma separation membrane is integrated into the platform. The article is written for a broad Analytical Chemistry audience, which would be interested in learning about blood and its components, blood-based diagnostics and assays for a variety of health issues using paper microfluidics.