DESIGN OF A MICROFLUIDIC CARTRIDGE FOR MALARIA DIAGNOSIS
Abstract
Malaria remains one of the deadliest diseases of the 21st Century, with 405,000 deaths annually. The visualization of stained blood smears with white light microscopy is still the gold standard for a proper diagnosis. Due to the difficulty of preparing consistent, high quality blood smears, effective malaria diagnosis remains challenging at the point of care (POC). Malaria diagnosis at the POC could be improved through the development of an automated smear preparation cartridge. In this work, materials for an automated smear preparation were developed and tested using bulk modifying polydimethylsiloxane (PDMS) with a poly(ethylene oxide) (PEO)-containing surface modifying additive (SMA). The modification was done at different concentrations, resulting in an increase in surface hydrophilicity as the concentrations of the SMA increased. The modified PDMS was optimized for the design of microfluidic cartridge for the generation of an automated, uniform, and repeatable blood smear by testing different SMA concentrations (3, 5, and 7 wt%) and blood volumes (0.3, 1, and 2 µl). Pillars were added at various locations throughout the channel, which served to prevent channel collapse and provide uniform cell distribution. With a target of cell uniformity (e.g. monolayer and cell density per area of 400-700 unique cells/ 0.024 mm2 field of view), the combination of 5 and 7 wt% SMA, 4.7 ± 0.1 µm height and 0.3 µl of blood was shown to provide a good quality smear within 15 min. Also, using flow control, a wet whole blood staining protocol was developed in the microchannel for automated staining at the POC. A 3X concentration Giemsa stain was created and diluted with DI water yielding 10% 33%, 50% concentrations and was tested to see which one worked best for staining malaria parasites. Although the results showed that for the 50% concentration the parasites were more distinguishable, this concentration also caused a crenation problem. Thus the 33% concentration showed the best contrast without crenation of RBCs. Further tests showed that the consistency for the 33% protocol was also good and that the parasites stained with 33% are equally or even more distinguishable than parasites from typical glass smear protocol.
Subject
malariamicrofluidic
smear
stain
POC
RDT
PCR
QBC
white light microscopy
malaria treatment
PEO
PDMS
Pillars
Giemsa
AO,
Citation
Dogbevi, Kokou Serge (2020). DESIGN OF A MICROFLUIDIC CARTRIDGE FOR MALARIA DIAGNOSIS. Doctoral dissertation, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /192880.