Deposit of Red Blood Cells at low concentrations in evaporating droplets: central edge growth and potential applications

TL;DR

This study investigates the deposit patterns of low-concentration blood droplets upon evaporation, revealing a central deposit formation influenced by fibrinogen and RBC shape, with potential diagnostic applications.

Contribution

It is the first to analyze the evaporation of blood samples with less than 1% RBCs, identifying a central deposit growth mechanism linked to the KPZ process and suggesting new diagnostic markers.

Findings

Central deposits dominate in samples with less than 1% RBCs.

Deposit growth follows the KPZ process with quenched disorder.

Deposit size is sensitive to fibrinogen levels and RBC shape.

Abstract

Evaporation of blood droplets and diluted blood samples is a topic of intensive research, as it is seen as a possible low-cost tool for diagnosis. So far, samples with volume fraction down to a few percents of Red Blood Cells (RBCs) have been studied, and those were reportedly dominated by a ``coffee-ring'' deposit. In this study, samples with lower volume fractions have been used in order to study the growth of the evaporative deposit from sessile droplets more in details. We observed that blood samples and salt solutions with less than 1\% volume fraction of RBCs are dominated by a central deposit. We characterized the growth process of this central deposit by evaporating elongated drops, and determined that it is consistent with the Kardar-Parisi-Zhang process in the presence of quenched disorder. Our results showed a sensitivity of this deposit size to the fibrinogen concentration and shape of the RBCs, meaning that this parameter could be used to develop a new and cost-effective clinical marker for inflammation and RBC deformation.