Conductive Textile Contact Resistance Control

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Solution Overview

Problem

Existing textile-based sensors face challenges in optimizing contact resistance, which limits their ability to effectively measure physiological data and other variables, as they often require multiple layers and cannot be worn closely against the skin due to design complexities and increased manufacturing costs.

Innovation Solution

A textile with fully integrated knitted sensors using a combination of jersey, miss, and tuck stitches to control contact resistance, allowing for adjustable electrical conductivity suitable for sensing activities like tensile force, compressive force, movement, and physiological activity, utilizing a single conductive yarn type and optimizing yarn contact areas for specific applications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional electrical circuits are constructed in textiles using conductive fibers knit or woven into fabric, then electrical conductivity is achieved, but the textile cannot be worn against the skin and is limited to small surface area

Engineering Contradiction:
Improveelectrical conductivityVSAvoidwearability and surface area coverage
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent merges the sensor function with the textile structure itself by integrating knitted sensors directly into the fabric using conductive yarns. The sensing areas are formed by specific stitch patterns (miss stitches and tuck stitches) that create controlled contact resistance, eliminating the need for separate sensor components and enabling full-surface wearability while maintaining electrical conductivity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent changes the physical parameters of the textile structure by using specific knitting stitch patterns (miss stitches and tuck stitches) that control the contact resistance between conductive yarns. By adjusting the stitch composition (e.g., 20-80% miss and tuck stitches), the electrical conductivity can be tuned to optimize both wearability and sensing performance across different surface areas.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If sensors are added to fabric in garments, then sensing capability is achieved, but design processes become complicated and manufacturing costs are increased

Engineering Contradiction:
Improvesensing capabilityVSAvoiddesign complexity and manufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent combines the sensor function with the garment fabric itself by knitting sensors directly into the textile structure using conductive yarns. The sensing areas are created through specific stitch patterns (miss and tuck stitches) that are integrated during the knitting process, eliminating separate sensor assembly steps and reducing manufacturing complexity and cost.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The textile structure serves dual functions: it provides the garment fabric and simultaneously acts as the sensor. The knitted pattern itself creates the sensing capability through controlled contact resistance between conductive yarns, making the textile self-sufficient and eliminating the need for additional sensor components or complex assembly processes.

Inventive Principle:
Principle #25Self-service

3Ease of manufacture

If a single conductive yarn type is used in knitted fabric for pressure and strain sensing, then manufacturing is simplified, but contact resistance control and sensitivity are insufficient

Engineering Contradiction:
Improveyarn type simplicityVSAvoidcontact resistance control and sensing sensitivity
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies local quality by using the same conductive yarn type throughout but creating different functional zones through specific stitch patterns. Miss stitches and tuck stitches are used in sensing areas to create controlled contact resistance and enhanced sensitivity, while other areas use standard knitting patterns. This allows precise control of electrical properties in specific locations without changing yarn types.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the structural parameters of the knitting pattern (stitch type, stitch composition, stitch density) rather than changing yarn types to control contact resistance and sensitivity. By adjusting the proportion of miss and tuck stitches (e.g., 20-80% range), the electrical conductivity and sensing sensitivity can be precisely controlled while maintaining manufacturing simplicity with a single yarn type.

Inventive Principle:
Principle #35Parameter changes

4Reliability

If stitch patterns with miss stitches and tuck stitches are used to control contact resistance, then electrical conductivity is optimized, but manufacturing complexity increases

Engineering Contradiction:
Improvecontact resistance controlVSAvoidstitch pattern complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The knitting machine and stitch pattern serve dual functions: they create the structural fabric and simultaneously optimize the electrical conductivity through controlled contact resistance. The miss and tuck stitches automatically create the desired electrical properties during the knitting process, making the complex stitch pattern self-justifying and eliminating the need for separate electrical optimization steps.

Inventive Principle:
Principle #25Self-service

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 textile structure provides a flexible, comfortable, and cost-effective solution for sensing various parameters without additional mechanical or electrical components, enhancing measurement accuracy and durability by controlling contact resistance and conductivity through predictable stitch patterns and yarn variables.

Implementation Method 1

a deformation-sensitive knitted or woven fabric structure of intertwined yarns having an electrical resistance that varies with degree of deformation

Methodology Applied
Scientific EffectElectrical Resistance: Electrical Resistance

Implementation Method 2

the thread contacts are made with piezo-resistive junctions such that contact resistance changes with applied pressure

Methodology Applied
Scientific EffectPiezo-resistive effect: Piezoresistive Effect

Implementation Method 3

Another fabric includes a pressure-activated electrical sensor integrated into a knitted fabric such that fiber contact resistance can be related to compression force

Methodology Applied
Scientific EffectPressure-activated electrical sensor: Piezoresistive Effect

Data Source

PatentEP2954108B1Electrically conductive textiles
Publication Date: 2022.04.06 FOOTFALLS & HEARTBEATS (UK) LTD
  • EP2954108B1 patent drawingFigure 1~2
  • EP2954108B1 patent drawingFigure 3A~3B
  • EP2954108B1 patent drawingFigure 4~5A

AI summary

A method for optimizing contact resistance in electrically conductive yarns and textiles, and textiles having such optimized contact resistance, can include selecting a sensing activity for the textile; selecting a combination of variables from among yarn variables, stitch variables, and textile variables; and knitting an electrically conductive yarn in the textile in accordance with the selected combination of variables, wherein the knitted combination of variables provides an optimal contact resistance in the textile correlated with a desired electrical conductivity for the sensing activity. The knitted combination of variables can provide a predictable yarn contact area for the electrically conductive yarn correlated with the optimal contact resistance.