Printed Digital Microfluidics for Diagnosis of Disease

Le résumé fourni par la source

Digital Microfluidics (DMF) is a liquid handling technology comprising the manipulation of discrete droplets using electrostatic forces. Droplets are sandwiched in between a counter-electrode top plate and a bottom plate bearing an array of insulated driving electrodes. In this configuration, individual droplets, each serving as micro-reactors, can be dispensed, mixed, merged, and separated making DMF a powerful sample handling and chemical processing technique. Complex multi-step operations can be performed in an automated fashion, and since droplets are individually addressable on a generic device geometry, experiments can be reconfigured on-the-fly. These properties make DMF an increasingly popular tool for lab-on-a-chip applications. While DMF has proven to be a useful technology, one of its leading challenges is fabrication—devices are typically manufactured on glass substrates with slow and expensive photolithography, wet-etching, vapour deposition, and spin-coating techniques that often require cleanroom facilities. There have been previous efforts forming DMF devices using cleanroom-free methods over the years, but the performance of the devices was limited, and the techniques were not scalable for mass manufacturing. This thesis introduces the development and use of tools for low-cost disease diagnosis at the point-of-care using a combination of microfluidic and printing technologies compatible with mass manufacturing methods. Chapter 2 demonstrates a novel method for forming DMF devices using a consumer-grade inkjet printer and a roll-coating technique compatible with mass manufacturing. The new devices were compared with those made using traditional cleanroom techniques, and their usefulness assessed by performing an infectious disease immunoassay. Chapter 3 describes the application of DMF devices in a point-of-care setting for the first time, with low-cost devices used to detect infectious diseases in a pair of field trials in Africa. Chapter 4 describes a DMF sampling interface allowing, for the first time, whole blood samples to be directly introduced to DMF devices for in-line and downstream analysis without pre-processing. Chapter 5 describes an integrated DMF and microchip electrophoresis device that uses low-cost materials and clean-room free fabrication techniques to allow for combined sample preparation and electrophoretic analysis. The developments in this thesis represent important steps towards facilitating DMF becoming a useful point-of-care diagnostic tool.

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