UHMWPE Indenter Probe for Ultra-Soft Material Characterization

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Solution Overview

Problem

Current techniques for measuring mechanical properties of ultra-soft materials are inaccurate due to their anisotropic and heterogeneous nature, leading to incorrect characterization, as they pierce through samples and fail to capture adhesion forces, which are critical for characterization.

Innovation Solution

A millimeter-scale ultra-high molecular weight indenter probe with a Young's Modulus of about 830 MPa, made of polymers like polyethylene, is used to accurately capture adhesion forces during indentation, combined with a light sensor for surface detection and force transduction, enabling characterization on a centimeter-scale.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional metal indenters are used for mechanical characterization, then the equipment is simple and easy to operate, but the indenter pierces through ultra-soft material samples and fails to capture adhesion forces, leading to inaccurate measurements

Engineering Contradiction:

Improveaccuracy of mechanical property measurementVSAvoidcomplexity of testing equipment

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent changes the material parameter of the indenter from conventional metal to ultra-high molecular weight polyethylene (UHMWPE) with a specific Young's Modulus of approximately 830 MPa. This parameter change allows the indenter to match the mechanical properties of ultra-soft materials, preventing piercing while maintaining measurement accuracy and capturing adhesion forces.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces an intermediary substance (UHMWPE material) between the indenter and the ultra-soft sample. This intermediary material acts as a mediator that transfers forces accurately without causing damage to the sample, enabling precise measurement of mechanical properties including adhesion forces.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If specialized techniques such as nano-indentation or AFM are used, then measurement precision is improved, but the techniques provide only narrow and localized nanoscale characterization and cannot perform measurements in ultra-soft heterogeneous systems

Engineering Contradiction:

Improveaccuracy of mechanical property measurementVSAvoidability to characterize heterogeneous ultra-soft materials

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent transitions from nanoscale localized characterization to macroscale characterization by using a millimeter-scale indenter (e.g., 10 mm diameter). This dimensional change allows the system to characterize ultra-soft heterogeneous materials across larger length scales, capturing bulk mechanical properties while maintaining measurement precision through the specialized UHMWPE indenter material.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Force

If metal indenters with high loads are used, then the indentation force is sufficient for measurement, but the indenter pierces through ultra-soft samples leading to grossly inaccurate estimation of mechanical properties

Engineering Contradiction:

Improveindentation forceVSAvoidaccuracy of mechanical property estimation

Core Design Contradiction:

ForceVSMeasurement precision

Solution Approach 1:

The patent changes the mechanical parameter (Young's Modulus) of the indenter material to approximately 830 MPa, which is suitable for ultra-soft materials. This parameter change allows the indenter to apply sufficient indentation force without piercing through the sample, thereby maintaining measurement accuracy.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach allows for accurate mechanical characterization of ultra-soft materials by capturing adhesion forces and providing a larger deformation volume, overcoming limitations of existing techniques and achieving results comparable to gold standards in ultra-soft material characterization.

Implementation Method 1

observation of the indenter probe approaching the ultra-soft samples via a sensor (e.g., a light sensor such as a camera)

Methodology Applied

Scientific EffectLight detection: Photoelectric Effect

Implementation Method 2

at least one force transducer in operable communication with the indenter probe and configured to sense force as the indenter probe approaches and comes into physical contact with the ultra-soft material

Methodology Applied

Scientific EffectForce sensing:

Implementation Method 3

The indenter probe can have a Young's Modulus of, for example, about 830 megaPascals (MPa) (e.g., 830 MPa+/−5%)

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS11275007B1Systems and methods for testing mechanical properties of ultra-soft materials

Publication Date: 2022.03.15 FLORIDA INTERNATIONAL UNIVERSITY

AI summary

Systems and methods for accurate characterization of the mechanical properties of ultra-soft materials in the meso/macro-length scale are provided. Through the use of a millimeter-scale, ultra-high molecular weight indenter probe, accurate mechanical characterization of ultra-soft materials on the centimeter-scale can be achieved. The indenter probe can capture the adhesion forces present during the approach and detachment segments of the indentation process.