Stretchable Sensor Reference Wire Resistance Correction
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Solution Overview
Problem
Existing flexible circuit boards used in motion sensors for detecting human or robot motion suffer from inaccurate resistance variation detection due to stretching, as the resistance of the wiring section varies significantly with stretching action, leading to unreliable motion detection.
Innovation Solution
A sensor design incorporating a stretchable substrate with a reference wire and multiple sensing wires, where the sensing wires exhibit larger resistance value variations than the reference wire, allowing for accurate detection of substrate extension and contraction by correcting resistance values based on the reference wire's readings, and detecting wire deterioration to ensure reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a flexible circuit board with stretchable wiring is used for motion detection, then the sensor can detect motion through resistance variation, but the resistance value varies significantly with stretching action leading to low detection accuracy
Solution Approach 1:
The sensor is divided into two functional segments: reference wires that remain substantially unchanged during stretching, and sensing wires that exhibit significant resistance variation. This segmentation allows the reference wires to provide a stable baseline while the sensing wires capture motion-induced changes, resolving the contradiction between stability and detection capability.
Solution Approach 2:
The patent utilizes parameter changes in wire resistance due to stretching. By designing sensing wires with specific geometric configurations (meandering patterns, loops) that amplify resistance changes during stretching, the system converts mechanical deformation into measurable electrical parameter changes, enabling accurate motion detection despite the inherent instability of stretchable conductors.
2Measurement precision
If multiple wires with different resistance variations are used, then accurate detection of substrate extension is possible, but the device complexity increases
Solution Approach 1:
Both reference wires and sensing wires serve the same basic function of electrical conduction, but differ in their geometric configurations. The reference wires provide a universal stable reference, while sensing wires provide motion-sensitive measurements. This multi-functionality approach allows a single wire structure to serve multiple purposes (reference and sensing) through configuration variations rather than fundamentally different components.
Solution Approach 2:
The sensing wires are essentially copies of the reference wire structure but with modified geometric configurations (meandering patterns, loops, serpentine shapes). These copied structures maintain electrical connectivity while introducing controlled resistance variations that amplify motion detection capability without requiring entirely different wire types or materials.
3Measurement precision
If the first wire is designed to extend and contract with shape deformation while the second wire extends with elastic deformation, then resistance variation due to substrate extension can be detected, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs flexible substrate materials that naturally provide the required deformation characteristics. The reference and sensing wires are patterned onto this flexible substrate, which acts as a compliant mounting surface. This approach eliminates the need for precise mechanical control of wire deformation during manufacturing, as the flexible substrate inherently accommodates the desired shape changes while maintaining wire integrity.
Solution Approach 2:
The sensing wires are designed with curved, meandering, or looped geometries rather than straight lines. These curved configurations amplify the resistance change response to substrate stretching while being naturally tolerant of manufacturing variations. The curved paths allow the wires to deform more uniformly and predictably during stretching, reducing the precision requirements for wire placement and deformation control.
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 achieves high accuracy in detecting resistance value variations due to substrate extension and contraction, while also prompting for maintenance to prevent degradation in detection accuracy, thereby enhancing reliability and convenience.
Implementation Method 1
the second wire extends and contracts together with the stretchable substrate with elastic deformation
Implementation Method 2
the first wire extends and contracts together with the stretchable substrate with shape deformation
Data Source
AI summary
A sensor includes a stretchable substrate having a stretching property, and a plurality of wires provided to the stretchable substrate, and the plurality of wires includes a first wire, and a second wire larger in resistance value variation due to extension of the stretchable substrate than the first wire. Further, the sensor includes a detection section adapted to correct a resistance value of the second wire in accordance with a resistance value of the first wire, and detect the extension of the stretchable substrate based on the resistance value of the second wire which has been corrected. Further, the detection section detects deterioration of the plurality of wires in accordance with the resistance value of the first wire.