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A high-throughput microfluidic technology for combinatorial drug screening
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Date
2025-12
Abstract
Rapidly advancing 3D organoid culture methods enable physicians and their patients to exploit individualised combinatorial medicine. However, established methods of robotic liquid handling for 2D combinatorial assays, on standard microplates, are inefficient, costly, and slow. For the industry to transition from 2D to 3D cell culture technologies, diagnostic platforms that can identify synergistic combinations are required. This would enable quick, effective treatment tailored to a patient's individual genetic, environmental, and lifestyle factors, which is an unmet need that this thesis, in part, aims to address. This thesis uses microfluidic engineering to develop technologies that can be leveraged for a scalable drug screening platform capable of mixing inputs in selectable combinations. Prototypes employ a novel method of aqueous-in-oil droplet generation, called Gap Switch Technology (GST), in which wells containing fluid exploit interfacial and capillary force interactions to control the flow. Only when a 10 mm long segment of tubing, called a shuttle, bridges with the well, is a sufficient pressure differential induced to transfer aqueous samples across a gap to the oil-primed shuttle. Once a predetermined volume has transferred, the shuttle mechanically translates and shears the fluid from the well, while wrapping it in the carrier oil phase. This creates a microenvironment in a droplet that is transferred to a reusable polytetrafluoroethylene (PTFE) channel for incubation and analysis.
Atmospheric, Partial and Total Immersion technologies, that immerse the shuttle in oil to varying depths, were successfully demonstrated on single radius prototypes by the generation of droplet sequences, each approximately 200 nL. Each technology iteration reduced volume tolerance, with Total Immersion achieving the industry goal of ± 5%.
Mechanical assembly variation reduction, coupled with negating the reliance on gravity-driven flow, by enabling pumping, in partially and totally immersed shuttle prototypes, resulted in droplet volume variation improvements which were measurable using optical methods.
A scalable rotor platform, which simultaneously generated droplets at four locations, from a selectable set of inputs, was realised by leveraging the development of single radii prototypes. This demonstrated the transfer of Partial and Total Immersion technologies to a scalable system.
Demonstration of system scalability was successfully achieved using an 8-well, 4-radii, rotational prototype to generate 28 pairwise droplet combinations, repeated five times, from static and movable rings carrying wells, as proof of concept for a platform that partly addresses unmet industry needs.
The findings in this thesis demonstrate core functions that are scalable for a 48 well x 4 ring concept system to control and generate >50 million droplet combinations. The Enigma IV platform developed in this thesis demonstrates how commercially relevant quantities of droplet combinations might be practically reached.
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University of Limerick
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Galvin_2025_High.pdf
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Sustainable Development Goals
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Attribution-NonCommercial-ShareAlike 4.0 International