Modeling Viscoelastic Flow Through Two-Layer Crossing-Channel Micromixers for Biomimetic Tissue Fabrication

Bioprinting has the potential to advance medicine by integrating living cells into complex living structures tailored to human needs. However, a key challenge remains in producing tissues with spatially varying material properties for improved biomimicry. Microfluidic mixers offer a promising solution by facilitating the combination of biomaterials with different properties in a controlled manner. Expanding on previous research that investigated the device's mixing efficiency with Newtonian fluids, this study simulates viscoelastic fluid flow through the micromixers to achieve a more accurate model of the viscoelastic bioink behavior in situ. Using a Discovery HR-3 rheometer, we measure the response of the biomaterial under an oscillatory load and determine the most suitable viscoelastic model and its parameters. Implementing the model's governing equations in ANSYS Fluent through User Defined Functions, we conduct simulations within the mixer to test various design geometries and boundary conditions, aiming to optimize mixing performance. The results from this study enable greater control over the resulting hydrogel properties, facilitating the creation of synthetic tissues with enhanced biomimicry and benefiting regenerative medicine and tissue engineering.