Development of a self-regulating paper-based microfluidic platform for instrument-free molecular diagnostics

Huang, Jiaxing (2026) Development of a self-regulating paper-based microfluidic platform for instrument-free molecular diagnostics. PhD thesis, University of Glasgow.

Abstract

This thesis addresses the engineering gap between laboratory-based nucleic-acid amplification tests and low-cost lateral-flow diagnostics by developing an instrument-free paper-based platform for amplified respiratory-virus detection. The work investigated three linked technological questions: whether a printed positive temperature coefficient ink heater could passively maintain the target thermal window without active feedback electronics; whether a dot-array nucleic-acid lateral-flow architecture could reduce the spatial and reagent-depletion limitations of conventional multi-line strips; and whether a thermally actuated wax gate could create a passive time delay to synchronise amplification with downstream detection.

A stencil-printed paper heater combining silver interdigitated electrodes with carbon-based positive temperature coefficient ink was developed and tuned for low-voltage operation. The heater exploited the intrinsic resistance increase of the composite to provide passive thermal regulation within the compatible range. A five-target dot-array lateral-flow strip was then developed for SARS-CoV-2, Influenza A/B and RSV A/B amplicons. Compared with the conventional line format, the dot-array layout reduced downstream signal depletion and enabled compact multiplex readout. On-paper amplification studies identified cellulose filter paper as a more suitable amplification and amplicon-release matrix than glass fibre. Finally, a thermally coupled wax-gate device was developed in which gate width programmed the actuation delay, allowing amplification products to be released only after the incubation period.

The integrated single-target prototype detected Influenza B synthetic DNA at an observed limit of detection of 200 copies total input. The work is presented as proof-of-principle engineering using synthetic DNA templates only; no recovery, extraction or purification of nucleic acids from clinical samples was performed. The thesis contributes design rules for printed self-regulating heating, dot-array nucleic-acid lateral-flow multiplexing, and passive thermal-fluidic synchronisation for future sample-to-answer paper diagnostics.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Subjects: Q Science > QR Microbiology; T Technology > T Technology (General)
• Colleges/Schools: College of Science and Engineering > School of Engineering
• Supervisor's Name: Reboud, Professor Julien and Cooper, Dr. Jonathan
• Date of Award: 2026
• Depositing User: Theses Team
• Unique ID: glathesis:2026-86109
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 14 Jul 2026 13:40
• Last Modified: 14 Jul 2026 13:40
• Thesis DOI: 10.5525/gla.thesis.86109
• URI: https://theses.gla.ac.uk/id/eprint/86109