Stretchable Device Cover Layer for Biocompatibility

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Solution Overview

Problem

Conventional stretchable devices with stretchable wiring on a substrate lack biocompatibility, leading to potential inflammation when worn on the human body due to the exposure of organic components, which can cause cytotoxicity and rash.

Innovation Solution

A stretchable device design featuring a stretchable substrate with stretchable wiring covered by a first cover layer, where the total organic carbon concentration in an extraction liquid after immersion in ultrapure water is 15 mg/L or less, ensuring biocompatibility by limiting the exposure of organic substances and suppressing cytotoxicity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If stretchable wiring with resin is used on a stretchable substrate, then device functionality is achieved, but biocompatibility deteriorates due to exposure of organic components

Engineering Contradiction:

Improvedevice functionalityVSAvoidbiocompatibility

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A cover layer is introduced as an intermediary between the stretchable wiring and the human body. This cover layer physically separates the organic components of the wiring from direct contact with skin, thereby maintaining device functionality while improving biocompatibility and preventing inflammatory reactions.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The cover layer is implemented as a flexible thin film that conforms to the stretchable nature of the underlying wiring and substrate. This flexible shell structure protects the organic components while allowing the device to maintain its stretchability and wearability on the human body.

Inventive Principle:

Principle #30Flexible shells and thin films

2Adaptability or versatility

If organic components are exposed in stretchable wiring, then device flexibility is maintained, but cytotoxicity increases causing inflammation

Engineering Contradiction:

Improvedevice flexibilityVSAvoidcytotoxicity

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The cover layer serves as a protective intermediary that prevents direct contact between organic components and biological tissue. This mediation eliminates cytotoxic effects while preserving the flexibility and adaptability of the stretchable wiring structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of manufacture

If conventional stretchable device structure is used, then manufacturing simplicity is achieved, but biocompatibility is insufficient leading to rash and inflammation

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidbiocompatibility

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The device structure is segmented into distinct functional layers: the stretchable substrate, the stretchable wiring layer, and the protective cover layer. This segmentation allows each layer to be optimized independently for its specific function while maintaining overall manufacturing simplicity through sequential fabrication processes.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cover layer is implemented as a flexible thin film that can be applied over the existing stretchable wiring structure. This approach maintains manufacturing simplicity by adding a protective layer without fundamentally changing the conventional fabrication process.

Inventive Principle:

Principle #30Flexible shells and thin films

Data Source

PatentUS20240397632A1Stretchable device

Publication Date: 2024.11.28 MURATA MFG CO LTD

AI summary

A stretchable device including: a stretchable substrate having a first principal surface and a second principal surface; a stretchable wiring on the first principal surface and containing a resin; and a first cover layer covering at least a part of the stretchable wiring, in which a total organic carbon concentration in an extraction liquid when the stretchable device is immersed in ultrapure water for 24 hours is 15 mg/L or less.