| dc.description.abstract | Point-of-care Diagnostics (POCD) is one of the rapidly growing areas of health-care sector
that avails to the needs of the patient at the point-of-care. An ideal POCD device is required
to be compact, portable, offer quick results, require no or minimal sample preparation, and
inexpensive with a low cost per test. Micro fluidics has a potential to cater to these needs,
thereby leading to a growing research interest to develop micro
uidic POCD (POCD) devices. POCD devices can be broadly categorized into cellular diagnostics and non-cellular
diagnostics. Micro
fluidic
flow cytometers (imaging and laser based) are the emerging diagnostics
tools for biological cell identi cation, categorization, and counting. Despite the advances
in this area these
flow cytometers have not yet been turned into POCD devices. This thesis
focuses on finding solutions for the major problems associated with these micro
fluidic
flow
cytometers towards becoming POCD devices. However, the developed techniques are quite
general and can be equally well applied for non-cellular diagnostics as well.
More specfi cally this thesis presents techniques for focusing of cells in
flow, in-
flow decantation,
and pumping along with the experimental demonstration of these techniques in the context
of deformability estimation of cells in
ow, blood cell counting, and quantitative microscopic
urinalysis. Focusing of the cells while in
flow is at the heart of the operation of
flow cytometers.
The developed technique reduces the complexity of fabrication and offers its applicability for a
wide range of
flow rates, thereby decreasing the cost per device and simultaneously offering the
flexibility of its use in both imaging and laser-based
flow cytometers. The in-
flow decantation
technique adds an extra dimension to the possibility of realizing sheath-free
ow focusing, by
separating the particle-free
fluid from the sample itself. The simplicity of the design and the
applicability of the technique for wide varieties of
ow rates, particle concentrations, and sizes
while having the ability to offer 100 % purity at high yields, offers its potential applications into
the realization of POCD that can operate on plasma separated from whole blood for several
biochemical assays, rare cell enrichment in cancer diagnostics, immunodiagnostics etc.
Pumping is an unavoidable task to cause
ow of either sample or sheath
fluids into the micro fluidic device. The developed pump uses the mechanical energy from the fingers and stores
inside an elastic block to cause pumping action when released subsequently. The pumping
mechanism is very general and is independent of the type of elastomeric block involved. However,
the
low rate quantity and stability depend upon the nature of stress-strain curve and the
stiffness of the elastomeric block used inside the pump. This pump is inexpensive (< 4 USD),
compact, portable, and reusable (> 500 times) making it as an ideal choice for the POCDs.
Using the developed
ow focusing device, deformability and the associated elastic moduli
of RBCs (that are obtained from healthy and diabetic subjects) and cancer cells (with and
without Emodine Anticancer drug treatment) were obtained and the results were found to be in
agreement with literature. To further demonstrate the applicability of the
ow focusing device
for blood cell imaging and counting, blood cells (Red Blood Cells - RBCs and White Blood
Cells - WBCs) in
ow were imaged and the counts were compared with standard hematological
analyzer counts. Similar experiments were performed on urine samples to demonstrate the
technique's applicability for quantitative microscopic urinalysis. Wide variety of cells that
can be found in Urine such as RBCs, WBCs, Epithelial cells, and Casts were imaged, and a
quantitative analysis was performed to infer the diagnosis and the observations were compared
with clinical results. All these results indicate the robustness of the developed techniques and
their excellent applicability for a wide range of POCDs. | en_US |
