Semester of Graduation
Spring 2026
Degree
Master of Science (MS)
Department
Biological and Agricultural Engineering
Document Type
Thesis
Abstract
Organ-on-a-chip (OoC) systems are biomimetic microfluidic platforms designed to replicate physiological microenvironments for in vitro investigation of human tissue function and drug response. While these systems possess great potential for drug discovery, they can be cumbersome to operate due to the bulky external pumping and valving required for precise fluid control. Recent advancements in solid-state microvalves provide an opportunity to simplify these architectures by integrating passive flow regulation directly within the microchip platform.
The present work began by identifying an optimal valve structure through computational fluid dynamic simulation of traditional and modern Tesla-like microvalve designs. Design constraints, including device scaling and geometry, were derived based on the specific requirements of rapid prototyping via resin 3D-printing and the low-Reynolds-number flow ranges characteristic of microfluidics. Initial investigations revealed that standard fabrication methods were insufficient for maintaining the high-fidelity features required for effective rectification. To address this, various preprocessing steps were evaluated to modify existing fabrication processes. Ultimately, a novel and unique fabrication technique was developed with the introduction of specialized geometry processing and the addition of an intermediate casting step (R-C-M), which significantly enhanced feature resolution and repeatability. To verify the fidelity of these devices, 3D optical profilometry was utilized. However, the transparent nature of the microfluidic structures posed a challenge for optical characterization. This was overcome by the development of a specialized titanium dioxide (TiO2) surface treatment, which enabled accurate 3D profilometry of transparent resins, elastomers, and other polymers used in this work.
Finally, the fabricated devices were evaluated in two distinct experimental phases. First, the experimental performance was compared against simulated results by leveraging existing OoC pneumatic flow control components for precise measurement of diode performance. Second, a specific OoC scenario was replicated and retrofitted to test the microvalve against a broad range of possible OoC pressure drop conditions. This allowed for the reporting of performance data under realistic conditions, providing a framework for the optimal implementation of passive valves in integrated systems. These findings demonstrate that modern solid-state valves, supported by robust fabrication and characterization techniques, offer a viable pathway towards reducing the complexity of next-generation OoC platform.
Date
4-15-2026
Recommended Citation
Semmes, Ignatius, "Design and Testing of 3-D Printed Solid-State Microvalves for the Suppression of Backflow in Organ-on-Chip Systems" (2026). LSU Master's Theses. 6383.
https://repository.lsu.edu/gradschool_theses/6383
Committee Chair
Monroe, Todd
LSU Acknowledgement
1
LSU Accessibility Acknowledgment
1