THESIS
2018
xxvii, 168 pages : illustrations (chiefly color) ; 30 cm
Abstract
Current microfluidics-based point-of-care diagnostic platforms require complex and
costly fabrication protocols, and bulky auxiliary fluidic instrumentation, limiting their impact
in resource-poor environments. 3D-printing has recently emerged as an enabling technology in
the manufacturing of microfluidic chips with integrated features iteratively and inexpensively.
Herein, I present a versatile, zero-equipment technique which utilizes built-in, torque-driven
piston pump-like components for enabling advanced microfluidic operations in 3D-printed
devices. By screwing along either thread direction, positive and negative volumetric
displacement pressures can be generated, triggering microactuation of fluidics along
microchannels, tubings, and capillaries. This mechanism can be expl...[
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Current microfluidics-based point-of-care diagnostic platforms require complex and
costly fabrication protocols, and bulky auxiliary fluidic instrumentation, limiting their impact
in resource-poor environments. 3D-printing has recently emerged as an enabling technology in
the manufacturing of microfluidic chips with integrated features iteratively and inexpensively.
Herein, I present a versatile, zero-equipment technique which utilizes built-in, torque-driven
piston pump-like components for enabling advanced microfluidic operations in 3D-printed
devices. By screwing along either thread direction, positive and negative volumetric
displacement pressures can be generated, triggering microactuation of fluidics along
microchannels, tubings, and capillaries. This mechanism can be exploited to operate complex
bioassays via multiple modalities, including chaotic mixing, reagent storage, and sequential
delivery, without any reliance on ancillary pumps, valves, or pressure sources.
In developing our torque-driven 3D-printed microfluidic chips, I first explored the
design and fabrication of threaded movable components, as well as characterization of the
finger-powered pumping method. Also, I investigated several methods for improving inertness
of the 3D-printed surface against biochemical fouling. A torque-driven, dual 3D-grooved
serpentine micromixer chip for rapid blood testing was presented as proof-of-concept
demonstration of device utility. Moving forward, I showed that our torque-based pumps can
also be utilized in a plug-and-play format in combination with conventional PDMS chips.
Furthermore, the pump can be modularly coupled with plug-loaded tubing cartridges to enable
sequential dispensing and oscillation of liquid plugs. By combining the torque pump
component with capture molecule-functionalized surfaces and reagent-loaded cartridges,
complex multi-step, multi-reagent heterogeneous bioassays can be easily performed within
stand-alone, disposable devices. I validated the performance of our platform by conducting a
slot blot immunofluorescence assay (IFA) for quantifying human IgG levels using
nitrocellulose-embedded 3D-printed chips. Additionally, I further developed a hybrid 3D-printed
plastic–glass capillary immunodiagnostic device. To demonstrate real-world
applicability, using our device I performed capillary-based enzyme-linked immunosorbent
assays (ELISA) and indirect IFA for diagnosing chronic Chagas disease in clinical samples.
To summarize, in this thesis I have presented an arsenal of 3D-printed microfluidics-based
point-of-care diagnostic devices powered by user-friendly torque-driven micropumps.
These micropumps were monolithically incorporated as finger-powered microfluidic control
elements within various point-of-care platforms. Advantages of our design include: low-cost,
portability, disposability, usability, and control of on-chip fluid actuation; thus, negating the
need for large external pumps or pressure sources. Therefore, torque-driven microfluidics
represent a critical development in zero-equipment disease diagnostics by enabling the finger-powered
operation of bioassays on miniaturized, integrated 3D-printed devices.
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