ABS 001: Characterizing Flow Dynamics Using Particle Imaging Velocimetry within Organ-on-a-Chip

M. Collins ¹ , ME. Viso ² , J. Datta ³ ⁵ , A. Agarwal ² ⁴ ⁵

¹ Department of Neuroscience, Brown University
² Department of Biomedical Engineering, University of Miami
³ Dewitt Daughtry Department of Surgery, University of Miami Miller School of Medicine
⁴ Desai Sethi Urology Institute
⁵ University of Miami Miller School of Medicine

Van Wickle (2025) Volume 1, ABS 001

Introduction: Organ-on-a-chip (OoC) mimics the dynamic biochemical and physiological environment of human organs. While mice models are commonly used as they provide a holistic view of diseases, they cannot demonstrate the mechanistic steps that govern specific cell interactions. Similarly, static cultures lack the perfusion needed to prevent necrosis in 3-dimensional models. OoC models address these issues, allowing real-time demonstration of cellular mechanics and offering precise control over the cell microenvironment and tissue-specific functions. To ensure full perfusion and maintain cellular viability in microfluidic platforms, a stable flow is required. Laminar flow mitigates shear stress, reduces metabolic volatility, and minimizes data inconsistencies, whereas a turbulent flow's high shear stress can damage cells and disrupt nutrient delivery.

Methods: This study aims to determine if our OoC model supports laminar flow, characterized by a predictable, consistent velocity, which is essential for preserving cell activity and health. We flowed fluorescent particles through the channels and recorded their trajectory, using micro-particle imaging velocimetry (μPIV) software to measure flow velocities and shear stress. By capturing time-lapse images of tracer particles and analyzing their displacement, we assessed the flow's pattern and the potential shear stress on cells. While in small volume microfluidic devices, the diameter is so minuscule that laminar flow can be assumed, our OoCs are created to sustain organoid/spheroid cultures. These tend to be larger and therefore require a larger clearance. This necessitates experiential measurements to confirm a laminar pattern.

Discussion: While 3-dimensional cell cultures are more advanced and offer a closer approximation to the in vivo environment, their complexity can lead to less consistent data compared to simpler 2D models. This is a result of the difficulty of maintaining laminar flow in large scale models. By characterizing flow dynamics, μPIV confirmed the presence of a consistent velocity and shear pattern throughout the channel. This analysis will help determine the suitability of the OoC model in ensuring that cells remain healthy and stabilized, resulting in reliable results.