Flexible Touch Sensor Structure for Curved Surfaces and Pressure Sensing

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Solution Overview

Problem

Capacitive touch sensors struggle to detect touch pressure and are limited in application to curved surfaces due to the use of cover glass, which restricts their flexibility and adaptability to various electronic device shapes.

Innovation Solution

A flexible touch sensor with a multilayer structure comprising a first and second nanoweb layer, a base layer, and circuit pattern layers, connected via an anisotropic conductive film, ensuring flexibility without cracks when wound around a 4 mm cylindrical mandrel, utilizing nanofibers and conductive powders for pressure detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a capacitive type touch sensor uses cover glass, then it can recognize touch position on a plane, but it cannot detect touch pressure and is limited in applying to curved surfaces

Engineering Contradiction:

Improvetouch position recognitionVSAvoidapplication to curved surfaces

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent replaces the rigid cover glass with a flexible nanoweb layer made of nanofibers. This nanoweb layer can conform to curved surfaces while maintaining touch sensitivity, enabling the sensor to be applied to various shapes including curved surfaces without sacrificing touch position recognition capability

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent uses a composite structure combining nanofibers, conductive powders, and polymer matrices to create a multifunctional touch sensor layer that provides both mechanical flexibility for curved surfaces and electrical conductivity for touch detection, simultaneously addressing both requirements

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If a flexible sensor is made without cover glass, then it can be applied to various types of curved surfaces, but it loses the ability to detect touch pressure

Engineering Contradiction:

Improveapplication to curved surfacesVSAvoidtouch pressure detection

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The nanoweb layer with its porous nanofiber structure compresses under touch pressure, changing the distance between conductive layers and thereby detecting pressure magnitude. The porous structure allows for elastic deformation and recovery, enabling both flexibility for curved surfaces and pressure sensitivity

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The patent utilizes changes in capacitance values caused by variations in the distance between conductive layers when the nanoweb compresses under pressure. By monitoring these capacitance parameter changes, the system can detect touch pressure magnitude while maintaining flexibility

Inventive Principle:

Principle #35Parameter changes

3Reliability

If a flexible circuit board is connected to a sensor body, then it enables electrical connection, but it may cause cracks when bent around small radii

Engineering Contradiction:

Improveelectrical connectionVSAvoidresistance to cracking when bent

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent introduces an anisotropic conductive film as an intermediary between the flexible circuit board and the sensor body. This film provides electrical connection while accommodating bending stresses, preventing cracks from forming in the circuit board when bent around small radii

Inventive Principle:

Principle #24Intermediary (Mediator)

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 facilitates elastic recovery and can be transformed into various shapes, providing enhanced flexibility and pressure sensitivity through a stacked structure with nanoweb layers and anisotropic conductive films, avoiding material limitations of traditional sensors.

Implementation Method 1

the connection part includes an anisotropic conductive film

Methodology Applied

Scientific EffectAnisotropic conduction: Anisotropy

Implementation Method 2

a capacitive type, an optical type, and the like, and displays a touch position by calculating coordinates based on a change in the capacitance value of each electrode line caused by the touch of a conductor through the electrode

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 3

The base layer may include at least one selected from polyimide(PI), polyethylene terephthalate(PET), polyethylene naphthalate(PEN), and polyurethane(PU)

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS12547284B2Flexible touch sensor

Publication Date: 2026.02.10 AMOGREENTECH CO LTD

AI summary

The present invention can provide a flexible touch sensor including: a body in which a first circuit pattern layer, a first nanoweb layer, a base layer, a second nanoweb layer, and a second circuit pattern layer are disposed to be sequentially stacked; a flexible circuit board connected to any one of the first and second circuit pattern layers of the body; and a connection part connecting the body and the flexible circuit board, wherein the connection part includes an anisotropic conductive film, and wherein when wound around a cylindrical mandrel with a diameter of 4 mm, a crack having a length of 3 mm or more does not occur, whereby the flexible touch sensor has excellent flexibility and can be transformed into various shapes.