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.