Development of front-end pre-analytical modules for integrated blood plasma separation

Abstract

Blood plasma separation is a fundamental step in numerous biomedical assays involving low abundance plasma-borne biomarkers. The interest in microscale blood plasma separation solutions has emerged with the development of microfluidic technologies in the early 2000s and has continued in recent years as few solutions have so far achieved both high yield and high purity without sample dilution, in volumes compatible with current clinical assays. Hydrodynamic or acoustic blood plasma separation microdevices have attracted considerable attention from the microfluidic community in the continuous separation of blood samples with a volume of a few mL due to their high throughput and insensitivity to clogging. However, obtaining a high yield from whole blood is challenging because the volume of red blood cells or hematocrit typically rises above physiological levels after each separation region, following plasma extraction. Some key parameters that influence the microfluidic blood plasma separation efficiency and yield of such devices have been investigated in this project. In particular, this project sought to establish experimentally, for the first time, the maximum hematocrit level and flow rate achievable in a microchannel, without hemolysis. Furthermore, the influence of flow fluctuation in syringe pumps, which are commonly employed in microfluidic setups, on the separation performance of blood plasma separation devices was investigated. These studies not only reveal the reasons behind the slow progress in the development of high-throughput microfluidic blood plasma separation devices capable of handling whole blood samples but also provides a framework for the design optimisation of future microfluidic blood plasma separation devices. While for low to mid-volume clinical sample volume (<4 mL), microscale solutions are viable, for high clinical sample volume (>4 mL) blood plasma separation traditional centrifugation approach remains the gold standard but is currently cost-prohibitive. In the third part of this thesis, a low-cost and open-source centrifugation setup for clinical blood sample volume has been developed. This centrifugation system capable of processing clinical blood tubes could be valuable to mobile laboratories or low-resource settings where centrifugation is required immediately after blood withdrawal for further testing.