Passive Probe Beam Strain Gauge Measurement

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Solution Overview

Problem

Existing materials testing probes face challenges such as high cost, limited force application, lateral motion causing measurement errors, and unsuitability for miniaturization due to complex actuator arrangements, leading to inaccurate displacement and force measurements.

Innovation Solution

A passive materials testing probe with a rectangular beam, less than 5 mm long, equipped with strain gauges to measure deformation parallel to the axis, allowing precise force measurements by minimizing parasitic elastic deformation and lateral forces, and fabricated economically in batches.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a complex actuator arrangement is used to apply forces at micro and nano scales, then force application capability is improved, but device complexity and cost increase significantly

Engineering Contradiction:

Improveforce application capabilityVSAvoidactuator arrangement complexity

Core Design Contradiction:

ForceVSDevice complexity

Solution Approach 1:

The patent extracts the actuator from the probe itself, using an external actuator to apply forces while the probe remains a simple passive beam structure. This eliminates the need for complex integrated actuators while maintaining force application capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using an active beam with integrated actuators, the patent inverts the approach by using a passive beam measured by strain gauges, with actuation performed externally. This simplifies the probe design while maintaining testing capabilities

Inventive Principle:

Principle #13The other way round (Inversion)

2Force

If a cantilever beam is used to apply forces, then force application is enabled, but lateral motion occurs causing measurement errors

Engineering Contradiction:

Improveforce applicationVSAvoiddisplacement and force measurement accuracy

Core Design Contradiction:

ForceVSMeasurement precision

Solution Approach 1:

The patent uses a rectangular cross-section beam with asymmetric strain gauge placement to measure only axial deformation. The strain gauges are positioned to detect strain parallel to the primary axis while being insensitive to lateral bending motions

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent converts the unavoidable lateral motions into a non-problematic condition by designing the measurement system to be insensitive to them. The strain gauge configuration measures only axial strain, effectively filtering out lateral motion artifacts

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Length of moving object

If the beam length is reduced for miniaturization, then probe size is reduced, but manufacturing precision requirements increase

Engineering Contradiction:

Improvebeam lengthVSAvoidbeam fabrication precision

Core Design Contradiction:

Length of moving objectVSManufacturing precision

Solution Approach 1:

The patent changes the beam dimensions to a length less than 5mm (preferably less than 2mm or 1mm) and uses a rectangular cross-section, which are parameters that can be precisely controlled in batch manufacturing processes while enabling miniaturization

Inventive Principle:

Principle #35Parameter changes

4Measurement precision

If strain gauges are placed on the beam to measure deformation, then force measurement capability is improved, but parasitic elastic deformation affects accuracy

Engineering Contradiction:

Improveforce measurement accuracyVSAvoidparasitic elastic deformation

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent places strain gauges at specific locations on the beam where they measure only axial deformation. The gauges are positioned to be insensitive to lateral bending, creating local measurement zones that are selective for the desired measurement parameter

Inventive Principle:

Principle #3Local quality

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

Improves measurement accuracy and precision by increasing effective stiffness, reducing parasitic deformation, and enabling cost-effective, precise force measurements at micro and nano scales.

Implementation Method 1

Said beam comprises at least one measurement strain gauge configured to measure deformation of said beam in a direction parallel to said primary axis

Methodology Applied

Scientific EffectStrain gauge measurement: Piezoresistive Effect

Data Source

PatentEP4488653B1Materials testing probe

Publication Date: 2025.08.13 ALEMNIS AG

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AI summary

Materials testing probe (1) for a materials testing device (100), comprising: - a support (3) adapted to be coupled to said materials testing device (100); - a passive beam (5) having a length less than 5mm and extending from said support (3) along a primary axis (A), said beam (5) having a distal extremity (5c) adapted to cooperate with a sample (105) under test at least in a direction parallel to said primary axis (A). Said beam (5) comprises at least one measurement strain gauge (7) configured to measure deformation of said beam (5) at least in a direction parallel to said primary axis (A).