3D-Printed Microfluidic Interconnects for High-Throughput Bio-MEMS Applications

Abstract

Reliable fluidic interconnections remain a critical challenge in microfluidic systems, particularly for high-throughput applications requiring large amounts of inputs and outputs. Traditional interconnection methods often suffer from leakage, poor scalability, and complex assembly processes, limiting the development of high-throughput microfluidic platforms. These challenges become particularly acute in biological applications, where reliable fluid handling and contamination prevention are essential. The need for robust, scalable interconnect solutions has driven the development of new fabrication approaches and integration strategies.

This thesis presents a novel ultraviolet (UV)-assisted coaxial printing methodology as a solution to the microfluidic interconnect challenge. The approach combines precise control of material flow with in-situ UV curing to create reliable, scalable fluid connections. Through systematic investigation of printing parameters, including material flow rates, UV exposure conditions, pre-delay time and printing speed, an optimal processing window was established.

Computational fluid dynamics modeling provided crucial insights into the printing process, enabling the explanation of printing mechanism and geometry evolution. The resulting methodology demonstrates excellent reproducibility and reliability in creating sealed fluid connections.

The integration of these printed interconnects into functional microfluidic systems was achieved through the implementation of standardized assembly protocols. The research developed reliable interconnect arrays compatible with polydimethylsiloxane (PDMS) membrane-based devices and incorporated mechanical valving systems for controlled fluid manipulation. Characterization validated the system's performance through flow visualization, demonstrating successful scaling from single-well to multiplexed-microwell configurations. The integrated platform maintains consistent sealing across multiple connection points, enabling complex fluid handling operations in high-density arrays.

The practical application of this technology was demonstrated through the detection of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). A multiplexed microfluidic platform was developed, incorporating microcontact printing for controlled protein immobilization protocols. The integrated system successfully combined printed interconnects, protein patterning, and flow control to enable protein-protein interaction studies. The platform demonstrated reliable binding between SARS-CoV-2 Receptor-Binding Domain (RBD) and Angiotensin-Converting Enzyme 2 (ACE2), validating its potential for biological detection applications.

This research establishes a robust solution for reliable fluid connections in complex biological applications, addressing fundamental challenges in microfluidic technology. The developed approach demonstrates excellent potential for scaling to higher levels of multiplexing while maintaining consistent performance. These advancements enable new possibilities in biological research and diagnostic applications, particularly in scenarios requiring high-throughput analysis of multiple samples or conditions.

Date of Award	2025
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology
Supervisor	Yusong GUO (Supervisor) & Shi-wei LEE (Supervisor)