Fabric Force Sensor Layout for Wearable Accuracy and Flexibility

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Solution Overview

Problem

Fabric-based items with sensing circuitry often lack usability, aesthetic appeal, and accuracy in measurement due to their design and material limitations, as existing technologies do not effectively integrate force sensing capabilities into flexible and wearable forms.

Innovation Solution

A fabric-based item with force sensing circuitry featuring electrodes on a compressible elastomeric polymer substrate, intertwined conductive strands, and wireless communication capabilities, where stiffeners decouple adjacent sensor elements and mesh structures resist cracking, facilitating deformation and accurate force measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If fabric-based items include sensing circuitry, then measurement capability is provided, but the item becomes awkward to use and lacks attractive appearance

Engineering Contradiction:
Improveforce measurement accuracyVSAvoidusability
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The patent applies flexible printed circuits with mesh-shaped openings that allow the fabric to bend and conform to body contours while maintaining electrical connectivity. The serpentine flexible printed circuit segments extend between openings, providing flexibility and comfort for wearable operation.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The flexible printed circuit board incorporates a mesh shape formed from an array of openings, creating a porous structure that allows fabric breathability and flexibility while maintaining structural integrity and electrical signal transmission for force sensing.

Inventive Principle:
Principle #31Porous materials

2Measurement precision

If fabric-based items include sensing circuitry, then measurement capability is provided, but the item lacks attractive appearance

Engineering Contradiction:
Improveforce measurement accuracyVSAvoidaesthetic appearance
Core Design Contradiction:
Measurement precisionVSShape

Solution Approach 1:

The flexible printed circuit with mesh openings creates a visually appealing pattern that integrates seamlessly with fabric textures. The serpentine segments between openings provide both functional flexibility and aesthetic design elements suitable for wearable applications.

Inventive Principle:
Principle #30Flexible shells and thin films

3Measurement precision

If force sensor elements are formed on compressible substrate, then force measurement capability is provided, but adjacent sensor elements become coupled and measurement accuracy decreases

Engineering Contradiction:
Improveforce sensor measurement accuracyVSAvoidsensor element independence
Core Design Contradiction:
Measurement precisionVSStability of the object's composition

Solution Approach 1:

Stiffeners are positioned to overlap the electrodes and segment the compressible substrate into isolated regions. This segmentation decouples adjacent force sensor elements from each other, preventing mechanical coupling and ensuring independent measurement of each sensor element for improved accuracy.

Inventive Principle:
Principle #1Segmentation

4Loss of information

If fabric-based item uses wireless circuitry, then data transmission capability is provided, but power consumption increases

Engineering Contradiction:
Improvedata transmission capabilityVSAvoidpower consumption
Core Design Contradiction:
Loss of informationVSUse of energy by moving object

Solution Approach 1:

Wireless transmission of force sensor data occurs periodically or on-demand rather than continuously, reducing power consumption while maintaining data transmission capability for controlling external equipment.

Inventive Principle:
Principle #19Periodic action

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 provides a wearable and aesthetically pleasing fabric-based item that accurately measures force, conveying signals wirelessly for control and data processing, enhancing usability and measurement precision while maintaining flexibility and durability.

Implementation Method 1

each element comprising first and second electrodes, the substrate being interposed between the first and second electrodes. The capacitive force sensor circuitry measures an applied force by measuring a capacitance between the first and second electrodes.

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 2

a compressible dielectric substrate which is an elastomeric polymer substrate... The compressible substrate has opposing upper and lower surfaces. Electrodes for the force sensor elements are formed on the upper and lower surfaces.

Methodology Applied
Scientific EffectDielectric: Dielectric

Implementation Method 3

a compressible dielectric substrate which is an elastomeric polymer substrate... facilitate deformation of the compressible substrate

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3488208B1Fabric-based devices with force sensing
Publication Date: 2023.11.29 APPLE INC
  • EP3488208B1 patent drawingFigure 1
  • EP3488208B1 patent drawingFigure 2
  • EP3488208B1 patent drawingFigure 3

AI summary

A fabric-based item such as a fabric glove may include force sensing circuitry. The force sensing circuitry may include force sensor elements formed from electrodes on a compressible substrate such as an elastomeric polymer substrate. The fabric may include intertwined strands of material including conductive strands. Signals from the force sensing circuitry may be conveyed to control circuitry in the item using the conductive strands. Wireless circuitry in the fabric -based item may be used to convey force sensor information to external equipment. The compressible substrate may have opposing upper and lower surfaces. Electrodes for the force sensor elements may be formed on the upper and lower surfaces. Stiff eners may overlap the electrodes to help decouple adjacent force sensor elements from each other. Integrated circuits can be attached to respective force sensing elements using adhesive.