Physical model of serum supplemented medium flow in organ-on-a-chip systems

TL;DR

This study develops a detailed physical model for serum-supplemented media flow in organ-on-a-chip systems, revealing non-Newtonian behavior and providing improved shear stress estimations for device design.

Contribution

It introduces a comprehensive rheological characterization of serum media and integrates it with flow measurements and simulations to enhance shear stress modeling in OOC devices.

Findings

Serum media exhibits non-Newtonian rheology.

Shear stress is significantly higher than previous estimates.

Provides formulas for accurate shear stress approximation.

Abstract

Creating a physiologically relevant shear stress in organ-on-a-chip (OOC) devices requires careful tailoring of microfluidic flow parameters. It is currently fairly common to use a simple approximation assuming a constant viscosity, even for serum-based media. Here, we show that a popular nutrient solution (Dulbecco's Modified Eagle Medium supplemented with Fetal Bovine Serum) requires a more complex treatment (i.e., is a non-Newtonian fluid), with observed shear stress values significantly greater than reported in literature. We measure the rheology of the solutions and combine it with a 3-dimensional flow field measurement to derive shear stress at the channel surface. We verify the experiments with numerical simulations, finding good agreement and deriving flow properties. Finally, we provide relevant expressions for shear stress approximation, suitable for development of OOC devices with various geometries.