3D printing of asymmetric re-entrant structures for microfluidics

• Main Author: Lim, Yu Fong
• Other Authors: Zhou Kun
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2024
• Subjects: Engineering; Physics
• Online Access: https://hdl.handle.net/10356/177870
• Institution: Nanyang Technological University

Traditional microfluidic fabrication methods are often limited by complexity and cost. In contrast, 3D printing offers rapid prototyping and intricate geometries, especially beneficial for asymmetric re-entrant structures. Techniques like stereolithography (SLA), digital light processing (DLP), and selective laser sintering (SLS) enable high-resolution printing of complex features crucial for efficient fluid control. Applications span from lab-on-a-chip diagnostics to organ-on-a-chip platforms and microscale reactors. Customized microfluidic devices with tailored functionalities are empowering advancements in biomedical engineering, offering solutions for complex fluidic challenges at the microscale. Despite significant advancements, the majority of natural and artificial structures struggle to enhance the Laplace pressure difference or capillary force, resulting in a low unidirectional capillary height (< 30 mm). In this study, asymmetric re-entrant structures featuring long horizontal overhangs and interconnected forward/lateral microchannels were fabricated using three-dimensional (3D) printing. This led to substantially increased unidirectional capillary heights of 102.3 mm and 44.6 mm for water and ethanol, respectively, nearing the theoretical limits. Building upon both asymmetric and symmetric re-entrant structures, we introduce the concept of liquid transistors to programmatically adjust capillary rise. These liquid transistors hold promise for developing functional microfluidic devices capable of high-efficiency liquid-patterning, desalination, and biochemical microreactions in 3D space.