Exploiting PCB manufacturing techniques for point-of-care microfluidic assays

Abstract

Microfluidics have been an enabling technology for Point-of-Care (PoC) diagnostic platforms allowing them for handling minute sample volumes, lowering assays cost, and overall providing quick access to diagnosis. However, developing PoC platforms that are optimised for meeting the “ASSURED” criteria (affordable, sensitive, specific, user friendly, robust and rapid, equipment-free and deliverable to end-users), remains a challenge. To that end, printed circuit board (PCB) manufacturing processes provide an alternative competitive approach to quantitative PoC analytical platforms, allowing for electronic components, sensors and microfluidics to be integrated on a monolithic manner. This work was carried in collaboration with Newbury Electronics Ltd for developing standardised microfluidic components for sample and reagents manipulation, all via commercially available PCB processes. More specifically, throughout this PhD programme a design methodology and fabrication process was established for mass producing PCB-based fluidic components. Initially, the industrial fabrication processes were optimised while geometrical tolerances were studied and design rules identified. In parallel, a synchronised simulation method between COMSOL Multiphysics® and SOLIDWORKS® of low computational cost combining laminar flow, heat transfer and diffusion models was developed. Appropriate design rules and methodologies were introduced that allowed demonstrating a pressure and flow rate balanced serial dilution unit cell that can generate modular step-wise dilution networks. Additionally, a PCB based thermally regulated diluter was computationally studied. Finally, the introduced Lab-on-PCB technology was further equipped with passive microfluidic capabilities for the first time. An oxygen plasma-based method was introduced for rendering PCB surfaces hydrophilic and was applied on industrially manufactured microfluidic PCBs. Subsequently, capillary pumps comprising micropillar arrays combined with microfluidic channels on PCB were developed. Constant and design-controlled filling flow rates were achieved manipulating both, aqueous solutions and whole blood samples. This work overall enhanced the benefits of PCB-based PoC diagnostics by enabling commercially available microfluidic modules for sample preparation and manipulation.

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Identifiers

ORCID for Themis Prodromakis: orcid.org/0000-0002-6267-6909

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