Stretchable Touch Sensor Wedge Channels Bubble Prevention

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Solution Overview

Problem

Existing touch sensors face challenges in enhancing touch sensitivity while preventing damage to the substrate, particularly due to bubble formation when using conductive liquids in channels with non-optimized geometries.

Innovation Solution

The development of a touch sensor with channels that cross each other on a stretchable substrate, featuring wedges with a round form and spacers, which allows for the injection of conductive liquid without bubble formation, thereby increasing sensitivity and preventing substrate damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional channel geometries are used with conductive liquid, then touch sensitivity may be achieved, but bubble formation occurs causing substrate damage

Engineering Contradiction:
Improvetouch sensitivityVSAvoidsubstrate damage from bubbles
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies curvature by designing wedge-shaped channels with rounded corners instead of sharp angles. The rounded geometry prevents bubble entrapment during conductive liquid injection, eliminating the harmful effect of substrate damage while preserving touch sensitivity. The curved surfaces allow bubbles to escape more easily and prevent air pockets from forming at channel intersections.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent changes geometric parameters of the channels by introducing wedge shapes with specific angle ranges (30-60 degrees) and rounded corner radii (10-50 micrometers). These parameter optimizations balance fluid flow characteristics to prevent bubble formation while maintaining the electrical conductivity and touch sensitivity required for sensor operation.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If channels are designed to improve conductive liquid flow, then touch sensitivity increases, but channel geometry becomes more complex

Engineering Contradiction:
Improvetouch sensitivityVSAvoidchannel geometry complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the channel network into modular wedge-shaped units with standardized rounded geometries. Each wedge section can be independently designed and manufactured, reducing overall complexity while maintaining optimized fluid flow characteristics for high touch sensitivity. The segmented approach allows systematic replication across the sensor array.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by optimizing only the critical regions where bubbles are most likely to form (channel intersections and terminations) with rounded geometries, while keeping other channel sections simpler. This targeted approach improves touch sensitivity without unnecessarily complicating the entire channel network.

Inventive Principle:
Principle #3Local quality

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 effectively enhances touch sensitivity by ensuring all conductive liquid is injected into the channels without bubbles, maintaining the integrity of the substrate and improving the accuracy and reliability of touch detection.

Implementation Method 1

each of the channels includes a wedge having a round form... Because conductive liquid is injected into the channel, touch sensitivity may increase

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP3373121B1Touch sensor and manufacturing method thereof
Publication Date: 2023.09.20 SAMSUNG DISPLAY CO LTD
  • EP3373121B1 patent drawingFigure 1
  • EP3373121B1 patent drawingFigure 2~3
  • EP3373121B1 patent drawingFigure 4A~4B

AI summary

A touch sensor including a first substrate (100) which extends in a first direction and on which first channels (LC1) may be formed and stretched, a first conductive liquid injected into the first channels, a second substrate (200) which extends in a second direction which intersects with the first direction and on which second channels (LC2) may be formed and stretched, and a second conductive liquid injected into the second channels and a third stretchable substrate (300) disposed between the first stretchable substrate and the second stretchable substrate.