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CHARACTERIZATION OF MICROFLUIDIC COMPONENTS FOR
LOW-COST POINT-OF-CARE DEVICES S. Hugo
1* , K. Land
1 and H. Becker
2
1Council for Scientific and Industrial Research, SOUTH AFRICA and
2microfluidic ChipShop, GERMANY
ABSTRACT
This paper presents the characterization of microfluidic components for the realization of low-cost point-of-care
diagnostic devices, with focus on full blood count applications. We present a set-up to enable automated actuation of
device components utilizing parameters similar to those produced by manual actuation. Initial results show that simple
microfluidic components can be used to achieve repeatable and accurate results for sample and reagent introduction and
propulsion, as well as mixing and dispersion of sample and reagent, without the need for complex microfluidic
operations.
KEYWORDS: Simple microfluidic components, Blister pack, Point-of-care, Full blood count
INTRODUCTION
Increasing emphasis is being placed on low-cost point-of-care diagnostic systems, particularly in under-resourced
settings [1] to enable instant diagnosis and to improve healthcare. Although numerous and varied advances in the field of
microfluidics have enabled point-of-care systems to be realized [2], there is often a trade-off between cost and operational
integrity of the device. This work addresses these limitations by exploring the minimum requirements for microfluidic
component complexity to achieve results equivalent to those of accepted standard techniques for blood cell counting
applications and illustrates the repeatability and robustness of device components for 1) sample introduction into the
device through a plugging mechanism, 2) reagent introduction and propulsion via a blister pack, and 3) mixing and
dispersion of sample and reagent. The successful implementation of these components rely on the forces and speeds
applied to the components for actuation, and were investigated in this work towards the development of a final device.
FUNCTIONAL PRINCIPLE
The simple microfluidic components were integrated into a device that was manufactured using injection molding.
Figure 1 shows the microfluidic device components to prepare a sample of blood for visual analysis using a dilution
factor of 1:20.
Figure 1: (a) Microfluidic device showing sample inlet port (A), blister pack (B), mixing chamber (C), air actuation
port (D), and visualization chamber (E). (b) Schematic designs of the expected fluid flow resulting from actuation for
inlet port plugging (A), blister pack compression (B) with subsequent mixing (C), and air actuation for dispensing of
sample (D) into visualization chamber (E).
EXPERIMENTAL
An experimental set-up was implemented to allow for detailed characterization of each of the microfluidic device
components. Figure 2 shows the set-up with the parameters that can be set and measured. An external syringe pump is
used for air actuation. High speed cameras provide side and bottom views of the microfluidic device, enabling volumes,
flow rates, as well as positions and times of contact of the actuators with the device components to be determined.
For initial testing, the sample was a 10 µl blood simulant containing yeast cells (5 x1012
cells per liter), to represent an
average red blood cell concentration found in human blood. The blister pack mounted on the microfluidic device con-
tained 190 µl colored water to simulate the blood preparation reagent to be mixed with the blood simulant.