Flexible Sensor Strip Resolving Bending and Stretching Measurement Contradictions
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Solution Overview
Problem
Existing flexible sensor strips for measuring geometric shapes and movements are tedious to produce and prone to errors, particularly when detecting tensile or compressive stresses that can be misinterpreted as bending measurements.
Innovation Solution
A flexible sensor strip with a polyethylene terephthalate (PET) substrate and resistor pairs arranged in a voltage divider configuration, allowing for accurate measurement of geometric shapes and movements by compensating for mechanical deformations through resistance changes, and featuring a compact design for easy production and low-cost manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strain gauges are used to record stretching deformations, then measurement sensitivity is improved, but tensile or compressive stresses cause false measurements that reduce reliability
Solution Approach 1:
The sensor strip is divided into multiple independent resistor pairs (first and second resistor pairs) arranged in different orientations. Each resistor pair measures deformation in its specific direction, allowing the system to segment the measurement of different deformation components (bending vs. stretching) and combine them for accurate results.
Solution Approach 2:
Different resistor pairs are positioned and oriented differently on the substrate - some parallel to the longitudinal axis and others perpendicular. This local variation in resistor orientation allows each element to specifically detect certain deformation types while being insensitive to others, improving overall measurement reliability.
2Adaptability or versatility
If a flexible substrate is used to allow bending and twisting, then adaptability is improved, but manufacturing precision deteriorates due to deviations in resistor positioning
Solution Approach 1:
The patent employs asymmetric arrangements of resistor pairs with different orientations (parallel and perpendicular to the longitudinal axis) rather than symmetric placements. This asymmetric design makes the sensor inherently more robust to manufacturing variations by distributing measurement functions across differently oriented elements.
Solution Approach 2:
The invention changes the orientation parameter of resistor pairs relative to the substrate's longitudinal axis. By arranging resistors at different angles (0 degrees and 90 degrees), the system creates measurement redundancy that compensates for positioning deviations, maintaining manufacturing tolerance while preserving flexibility.
3Measurement precision
If multiple resistor pairs are added to improve measurement accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
Each resistor pair serves multiple functions: it detects bending in its orientation direction, provides reference for differential measurement, and contributes to temperature compensation. This multi-functionality allows accurate three-dimensional movement detection using a relatively simple structure without requiring separate sensor elements for each function.
Solution Approach 2:
The patent combines multiple measurement functions (bending detection in different directions, stretching detection, temperature compensation) into a single integrated sensor strip structure with resistor pairs that simultaneously perform multiple roles. This merging reduces overall device complexity compared to using separate dedicated sensors for each function.
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
The sensor strip provides accurate and reliable measurements of geometric shapes and movements, including bending, twisting, and stretching, with improved tolerance for manufacturing deviations and reduced mechanical load on the contact region, enhancing its durability and measurement precision.
Implementation Method 1
When such a sensor strip experiences suitable mechanical deformations, such as bendings, twistings (torsions), stretchings, compressions, or the like, individual ones of these electrical elements can be stretched and others compressed. Changes in the resistance or capacitance values ensuing from this can be detected by means of an evaluation unit.
Data Source
AI summary
The present invention relates to a flexible sensor strip for measuring geometric shapes, in particular bending radii or the like, and to an associated device which can process and evaluate sensor signals of the sensor strip. The sensor strip comprises a substrate, on which a plurality of resistor pairs is arranged. Each of these resistor pairs has a resistor on the substrate front side and a further resistor on the substrate rear side. Both of these resistors are connected in series and between the poles of a supply voltage so that they form a voltage divider. The special feature of the present invention is that an electrical via and/or a pair of electrically interconnected contact elements is provided for the series circuit, that is, for the connection between the two resistors. When the substrate or the sensitive region of the sensor strip is moved into itself, in particular in the event of bending and/or twisting (torsion), the mid voltages in the affected voltage dividers change. This is sensed and evaluated by the measuring device according to the invention.