Towards the Development of a Well-less Tape-based Platform for High-Throughput Experimentation

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Abstract

High-throughput experimentation (HTE) is a concept used throughout industry and academia due to its potential at reducing resource consumption and experiment times. However, current technologies require the use of bulky, sophisticated robotics for manipulation, or carrier fluids that may interfere with experiments. This thesis presents work done towards the development of a simple and novel alternative that will uses arrays of sessile droplets on mobile thin polymer tape in open systems as a means of performing HTE. The tape-based platform prototype constructed uses a geared stepper motor-driven reel-to-reel tape translation system, which sessile droplets can be dispensed onto, incubated and analysed. Sessile droplet arrays are produced using micro-solenoid-based dispensers attached to a simple, programmable, cantilever style robot, fabricated in-house. To incubate sessile droplet arrays, the tape travels within a shallow groove across a long flat hot water radiator, and through a prototype humidifier system; with mechanical guides on either end of the radiator to ensure that the entirety of the tape makes contact with the surface. The prototype has sufficient space after the humidifier system to allow construction of a detection system. Burst gravimetry and various image analysis techniques showed that the selected dispensing devices were capable of reliably dispensing nL volumes of aqueous droplets onto tape with industrially acceptable levels of precision. Using individually addressable dispensers, sample and reagent solutions were successfully mixed within 0.2 s, using an “orthogonal successive micro-mixing” method. Various methods were tried to non-invasively suppress evaporative loss. Using fluorescence based image analysis, the prototype humidifier was shown to be a more effective, while the use of sacrificial droplets proved the less effective. Though none of the techniques trialled are currently capable of completely suppressing evaporative loss for indefinite amounts of time. A calibration for fluorescein was successfully demonstrated using a PMT-based LIF system, but analysis of data showed heteroscedasticity, and weighted linear regression produced a poor sensitivity (LOD (3σ) = 9.41 μM) in comparison with conventional HTE platforms. From the findings of the experiments conducted, progress has been made towards the development of the tape-based platform for HTE. Though a number of design flaws were identified in the prototype, but with further work it is believed that this concept has the potential to become a viable alternative to conventional HTE platforms in both industry and academia.

Keyword(s)

Droplet microfluidics; High-throughput experimentation; Microplates; Sessile droplets

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