Capacitive Sensing Fiber Yarn for Flexible Low-Cost Textiles
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Solution Overview
Problem
Current piezoelectric threads are costly, difficult to produce in long lengths, and lack flexibility, making them unsuitable for use as warp yarn in woven fabrics or warp knitting due to their rigidity and high production costs.
Innovation Solution
A sensing fiber member is created by wrapping low electrical conductivity fibers around a linear conductor, allowing for the detection of changes in resistance and electrostatic capacitance, which enables the production of flexible and cost-effective yarns suitable for woven or knitted fabrics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If piezoelectric material is used for contact sensing yarn, then sensing function is achieved, but production cost increases significantly and productivity decreases
Solution Approach 1:
The patent replaces expensive piezoelectric materials with inexpensive conductive fibers and insulating coverings that can be mass-produced through standard textile processes. The conductive fibers serve as disposable sensing elements that achieve the same function at a fraction of the cost, with production costs reduced from 1000-5000 yen per meter to significantly lower amounts through conventional plating and covering techniques.
Solution Approach 2:
The patent changes the sensing mechanism from piezoelectric effect to electrostatic capacitance change detection. By measuring changes in electrostatic capacitance between adjacent conductive fibers when contacted or approached by an object, the system achieves sensing functionality without requiring expensive piezoelectric materials, thereby improving productivity and reducing costs while maintaining reliable sensing performance.
2Reliability
If piezoelectric material is used for contact sensing yarn, then sensing function is achieved, but the yarn length is limited and cannot be produced in long lengths
Solution Approach 1:
The patent divides the sensing yarn into segments of conductive fibers separated by insulating coverings. This segmentation allows the yarn to be produced in long continuous lengths using standard textile processes, overcoming the limitation of producing only short segments with piezoelectric materials. The segmented structure maintains sensing functionality while enabling production of yarns 10,000 meters or longer.
3Reliability
If piezoelectric material is used for contact sensing yarn, then sensing function is achieved, but the yarn rigidity increases and flexibility decreases
Solution Approach 1:
The patent uses flexible insulating coverings and soft conductive fiber materials that maintain yarn flexibility while providing sensing functionality. The covering materials and fiber selections ensure the yarn remains pliable and suitable for textile applications, contrasting with the rigidity introduced by piezoelectric materials. This allows the yarn to be used in woven and knitted fabrics without compromising flexibility or comfort.
4Reliability
If conventional insulators are used between electrode pairs, then insulation is provided, but electrode distance variation is limited and sensitivity decreases
Solution Approach 1:
The patent employs flexible insulating coverings that allow dynamic variation in electrode distances between adjacent conductive fibers. This dynamic structure enables the sensor to detect subtle changes in capacitance as objects approach or contact the yarn, significantly improving sensitivity compared to rigid insulator structures with fixed electrode spacing. The flexible design allows optimal sensing performance while maintaining reliable insulation.
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 solution allows for the production of sensing fibers that can be processed to long lengths, providing excellent mass productivity and a pliable feel, while significantly reducing costs compared to traditional piezoelectric threads, enabling their use in various applications such as smart textiles and contact sensing fabrics.
Implementation Method 1
change in electrostatic capacitance between the linear conductors of the two mutually adjacently disposed covered yarns is read off
Implementation Method 2
change in resistance and/or change in electrostatic capacitance between the linear conductors of the two mutually adjacently disposed covered yarns is read off
Data Source
AI summary
Provided is a sensing fiber member which can be processed in long lengths, which excels in mass production, which is supple and has an excellent texture, and which is much less costly than a contact sensing fiber member (a piezoelectric yarn) for which a conventional piezoelectric material is used. This sensing fiber member has at least two covering yarns for which covering is achieved by wrapping an insulating fiber serving as a covering material in one direction around a linear conductor constituting a core material, two of the covering yarns being arranged close to each other. The sensing fiber member is characterized by reading changes in resistance and/or changes in capacitance between the linear conductors of the two covering yarns arranged close to each other.