Semi-transition structure for stretchable electronics strain distribution

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Solution Overview

Problem

The transition between stretchable and rigid or flexible electronic structures in combined devices is a weak point prone to breaking due to differential strain under mechanical stress, leading to reduced device lifetime.

Innovation Solution

Incorporating a semi-transition structure with a Young's modulus intermediate between the stretchable and rigid/flexible structures to distribute mechanical stress more evenly, reducing the strain gap and creating a semi-stretch transition zone that absorbs stress over a larger area.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a stretchable structure is directly connected to a rigid or flexible structure, then the device can achieve both stretchability and functionality, but the transition region creates a weak point where the circuit tends to break easily due to strain concentration

Engineering Contradiction:
ImprovestretchabilityVSAvoidconnection strength
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

A semi-transition structure with intermediate Young's modulus is introduced between the stretchable and rigid/flexible structures. This intermediary structure has mechanical properties that are neither fully stretchable nor fully rigid, allowing it to bridge the strain mismatch and distribute stress more evenly across the transition region, thereby preventing strain concentration and improving connection reliability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The Young's modulus parameter is gradually changed through the semi-transition structure, transitioning from the low modulus of the stretchable structure to the high modulus of the rigid/flexible structure. This gradual parameter change prevents abrupt mechanical property transitions, reduces stress concentration, and improves the overall reliability of the connection.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If the young modulus of the transition structure is mismatched with the stretchable and rigid/flexible structures, then the structure can maintain distinct functional zones, but plastic deformation concentrates at the transition creating a weak point

Engineering Contradiction:
Improvefunctional differentiationVSAvoidresistance to plastic deformation
Core Design Contradiction:
Adaptability or versatilityVSStrength

Solution Approach 1:

The semi-transition structure provides local quality variation by having different Young's modulus values at different locations along the transition zone. The structure gradually transitions from stretchable to rigid properties, creating local regions with intermediate mechanical characteristics that distribute plastic deformation and prevent concentration at a single weak point.

Inventive Principle:
Principle #3Local quality

3Reliability

If a semi-transition structure with intermediate young modulus is introduced, then stress distribution is improved and lifetime is increased, but the device complexity increases

Engineering Contradiction:
Improvedevice lifetimeVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The transition zone is segmented into multiple regions with progressively different mechanical properties. Rather than a single abrupt transition, the structure is divided into segments that gradually change from stretchable to rigid characteristics, distributing the transition over a longer length and reducing overall complexity while improving stress distribution.

Inventive Principle:
Principle #1Segmentation

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 semi-transition structure effectively reduces plastic deformation and stress concentration, increasing the overall device lifetime by distributing mechanical stress more evenly across the transition region.

Implementation Method 1

the semi-transition structure having a third young modulus with a value in a range between the first and the second young modulus

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

the semi-transition structure allows improving the repartition of mechanical stress in the stretchable substrate during any strain (elongation or torsion) of stretchable electronics

Methodology Applied
Scientific EffectStress distribution:

Implementation Method 3

a concentration of plastic deformation at the transition between both structures is introduced

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Implementation Method 4

The semi-stretch zone is designed to have less deformation under a stress than the stretchable structure, as a result of which it is able to reduce the strain gap

Methodology Applied
Scientific EffectStrain absorption:

Data Source

PatentEP2392196B1Stretchable electronic device
Publication Date: 2018.08.22 INTERUNIVERSITAIR MICRO ELECTRONICS CENT (IMEC VZW)
  • EP2392196B1 patent drawingFigure 1~2(d)
  • EP2392196B1 patent drawingFigure 3~4
  • EP2392196B1 patent drawingFigure 5a~5h

AI summary

An electronic device comprising at least one combination of a stretchable electronic structure having a first young modulus and a rigid or flexible electronic structure having a second young modulus higher than the first young modulus, the stretchable electronic structure and the rigid or flexible electronic structure being electrically connected to each other by a semi-transition structure having a third young modulus with a value in a range between the first and the second young modulus.