Compression Test

In the field of biomaterials, hydrogels represent a unique challenge. Their high water content and porous structure mimic the extracellular matrix (ECM), making them ideal for tissue engineering and drug delivery. However, characterizing their mechanical properties requires more than standard industrial testing. A hydrogel is not merely a solid; it is a biphasic continuum of solid polymer and interstitial fluid.

At Matexcel, we recognize that the success of a medical device—whether a cartilage scaffold or a hemostatic dressing—depends on its mechanical competence. We provide expert-level Compression Testing Services designed specifically for soft, hydrated materials. By combining high-resolution instrumentation with advanced theoretical modeling, we help clients navigate the complex physics of hyperelasticity and poroelasticity to validate their products for clinical use.

Service Overview

Standard material testing labs often utilize load frames designed for metals or rigid plastics, which lack the sensitivity to measure the delicate forces associated with soft tissues. Matexcel fills this gap with specialized infrastructure.

• Low-Force Resolution: We utilize micro-testers with load cells ranging from 1 N to 500 N. This allows us to accurately capture the "toe region" of the stress-strain curve—the initial low-stiffness phase critical for cell-material interactions—without the noise artifacts common in high-capacity machines.  
• Physiological Environments: We reject "dry" testing. All hydrogel assessments are conducted in temperature-controlled fluid baths (37°C PBS or culture media) to maintain hydration. This prevents the formation of a dehydrated surface "skin" that can artificially inflate modulus values by orders of magnitude.

Technical Principles

Our analysis goes beyond reporting a simple Young's Modulus. We characterize the intrinsic behaviors that define hydrogel mechanics:

• Hyperelasticity: Hydrogels exhibit non-linear elasticity. We employ Neo-Hookean and Mooney-Rivlin constitutive models to describe the rubber-like elasticity of the polymer network, providing data that is independent of sample geometry.
• Viscoelasticity: Hydrogels are time-dependent. Under constant load, they deform continuously (Creep); under fixed deformation, stress decays over time (Stress Relaxation). These properties are vital for implants that must conform to tissue without causing pressure necrosis.
• Poroelasticity: In hydrated networks, load is shared between the solid matrix and the fluid. We analyze the Hydraulic Permeability, which governs how fluid flows through the gel, a critical factor for nutrient transport and shock absorption.

Technical Classification and Methodologies

Matexcel offers a comprehensive suite of compression protocols tailored to specific material needs.

Unconfined Compression

The standard method for determining stiffness and strength. A cylindrical sample is compressed between two lubricated platens, allowing radial expansion.

• Key Outputs: Young's Modulus, Compressive Strength, Failure Strain.
• Application: General screening of scaffold formulations and crosslinking density verification.   

Confined Compression

The sample is constrained within a rigid chamber and compressed by a porous piston. Fluid is forced to flow axially through the gel, mimicking the boundary conditions of articular cartilage and intervertebral discs.

• Key Outputs: Aggregate Modulus, Hydraulic Permeability.
• Application: Essential for load-bearing tissue replacements where fluid pressurization supports the load.

Indentation Testing

For samples that cannot be formed into perfect cylinders—such as thin coatings on implants, contact lenses, or explanted tissues—we use spherical or flat-punch indentation

• Key Outputs: Localized Elastic Modulus, spatial heterogeneity maps.
• Application: Non-destructive testing of final products and mapping stiffness gradients across a surface.  

Company Service Advantages

We position ourselves not just as a testing lab, but as a research partner.

• Consultative Approach: Every project begins with a technical consultation to select the exact strain rates, temperatures, and boundary conditions relevant to your target tissue.
• Custom Fixture Design: Hydrogels rarely come in standard shapes. Our in-house machine shop fabricates custom grips and baths for testing microspheres, tubes, and complex 3D-printed geometries.  
• Data Interpretation: We do not just deliver raw CSV files. Our PhD-level scientists analyze the data to calculate complex parameters like mesh size and permeability, providing a comprehensive report suitable for R&D decision-making and regulatory filing.

Contact us

Mechanical characterization is the bridge between a chemical formulation and a medical product. A hydrogel may have perfect biology, but if it fails mechanically, it fails clinically. Matexcel's Compression Testing Service offers the precision, physiological relevance, and theoretical depth required to cross that bridge. From defining the initial stiffness of a neural scaffold to proving the fatigue life of a knee implant, we provide the data you need to innovate with confidence.

How to Place an Order