Abstract
Patterns in dried droplets are commonly observed as rings left after spills of dirty water or coffee have evaporated. Patterns are also seen in dried blood droplets and the patterns have been shown to differ from patients afflicted with different medical conditions. This has been proposed as the basis for a new generation of low-cost blood diagnostics. Before these diagnostics can be widely used, the underlying mechanisms leading to pattern formation in these systems must be understood. We analyse the height profile and appearance of dispersions prepared with red blood cells (RBCs) from healthy donors. The red cell concentrations and diluent were varied and compared with simple polystyrene particle systems to identify the dominant mechanistic variables. Typically, a high concentration of non-volatile components suppresses ring formation. However, RBC suspensions display a greater volume of edge deposition when the red cell concentration is higher. This discrepancy is caused by the consolidation front halting during drying for most blood suspensions. This prevents the standard horizontal drying mechanism and leads to two clearly defined regions in final crack patterns and height profile.This article is part of a discussion meeting issue ‘A cracking approach to inventing new tough materials: fracture stranger than friction’.
Highlights
Blood droplet analysis has been used in forensics for many years [1]
It is only recently that its medical applications have received attention, where the patterns produced in dried blood are indicative of several important medical conditions [2,3]. These include carcinoma [4], anaemia, hyperlipemeia [5], thalasemia, jaundice [6] and many more [7]. These findings indicate the potential for a new generation of low-cost point of care diagnostics where all that is required is a droplet of patient blood and a standard surface
The appearance of the patterns formed by dried blood droplets with several different initial concentrations of red blood cells (RBCs) in plasma are shown in figure 1
Summary
Blood droplet analysis has been used in forensics for many years [1]. It is only recently that its medical applications have received attention, where the patterns produced in dried blood are indicative of several important medical conditions [2,3]. Crack initiation and propagation in drying dispersions is a complex yet reproducible process that is highly dependent on the properties of the particle system [14] This is why pattern formation can differentiate between small variations caused by illness. There are many mathematical models that are used to predict cracking patterns in a variety of drying systems [15,16,17,18,19], complications in blood systems make their application difficult One such complication is the redistribution of components that occurs in the early stages of drying, which is responsible for the ring-like profiles that develop in most circumstances [20]. Note that we have used two types of plasma in this study: the radiation used to treat substrates and the liquid component of blood
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
