Scaffold Porosity Simulator: Pore Size & Cell Infiltration Modeling

simulator intermediate ~10 min
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Infiltration depth = 1.2 mm — adequate for thin tissue constructs, permeability supports nutrient transport

With 200 μm pores, 80% porosity, 70% interconnectivity, and 15 μm cells, cells infiltrate ~1.2 mm deep with Kozeny-Carman permeability of 8.5×10⁻¹⁰ m².

Formula

k = ε³d² / (150(1−ε)²) — Kozeny-Carman permeability
S/V = 4ε / (d(1−ε)) — specific surface area for spherical pores
D_inf ∝ d × ε × IC / Dc — infiltration depth scaling

Architecture of Life Support

A tissue engineering scaffold is not merely a passive support — its three-dimensional pore architecture actively directs cell behavior. Pore size controls which cells can enter, porosity determines how much living tissue can grow within, and interconnectivity governs whether nutrients and oxygen can reach cells deep inside the construct. Getting this architecture right is the first critical step in engineering functional tissues.

Pore Size and Cell Migration

Cells migrate through scaffold pores by extending processes (filopodia and lamellipodia) that probe the local geometry. If pores are too small, cells cannot physically squeeze through; if too large, cells cannot bridge across and establish contact with pore walls. The optimal pore diameter typically ranges from 5 to 20 times the cell diameter, depending on cell type and whether migration or attachment is prioritized.

Permeability and Transport

The Kozeny-Carman equation relates scaffold permeability to porosity and pore size, providing a key design parameter for nutrient and oxygen transport. High permeability ensures convective nutrient delivery in perfusion bioreactors, while low permeability causes diffusion-limited regions where cells become hypoxic and die. This simulation computes permeability from your scaffold parameters and visualizes the resulting flow potential.

Design Trade-offs

Every scaffold design faces a fundamental tension: more porosity means more space for cells but less mechanical strength; larger pores improve infiltration but reduce surface area for attachment; higher interconnectivity aids transport but may compromise structural integrity. This simulator helps you navigate these trade-offs by visualizing the coupled effects of pore geometry on cell infiltration, nutrient transport, and available surface area simultaneously.

FAQ

What pore size is optimal for tissue engineering scaffolds?

Optimal pore size depends on the tissue type: 100-300 μm for bone, 200-400 μm for cartilage, and 20-100 μm for skin. Pores must be large enough for cell migration and nutrient diffusion but small enough to provide surface area for cell attachment.

What is scaffold porosity and why does it matter?

Porosity is the fraction of void space in a scaffold. High porosity (70-90%) provides room for cells, ECM deposition, and nutrient transport. However, increasing porosity reduces mechanical strength, so a balance must be struck for each application.

What is pore interconnectivity?

Interconnectivity measures how well pores are connected to each other. High interconnectivity ensures continuous pathways for cell migration, nutrient transport, and waste removal. Closed or dead-end pores trap cells and create necrotic regions.

How is scaffold permeability measured?

Permeability is measured by flowing fluid through the scaffold and applying Darcy's law: k = QμL/(AΔP), where Q is flow rate, μ is viscosity, L is length, A is area, and ΔP is pressure drop. The Kozeny-Carman equation provides a theoretical estimate from porosity and pore size.

Sources

Embed

<iframe src="https://homo-deus.com/lab/tissue-engineering/scaffold-porosity/embed" width="100%" height="400" frameborder="0"></iframe>
View source on GitHub