Microneedle Sheet Bending Resistance and Safety

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Solution Overview

Problem

Existing microneedle apparatuses face safety concerns during handling due to exposed microelements that can touch or get caught on objects before application, and there is a need for enhanced bending resistance to prevent fractures or ruptures during bending.

Innovation Solution

A microneedle sheet with microneedles formed from a water-soluble polysaccharide and water, where the water content is between 1% and 19% by mass, providing excellent bending resistance and ensuring the microneedles do not protrude until applied to the skin, thus preventing accidental contact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If microneedles are exposed on the roller surface, then microneedle penetration function is improved, but safety during handling deteriorates due to risk of touching or catching on objects

Engineering Contradiction:
Improvemicroneedle penetration functionVSAvoidsafety during handling
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

Instead of having microneedles exposed on the roller surface (conventional design), the invention inverts the configuration by embedding microneedles within a flexible sheet structure where they remain concealed until application. The microneedles are positioned such that they only protrude when the sheet is bent during skin application, thereby eliminating handling safety risks while preserving penetration function.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The microneedles are nested within the flexible sheet structure, concealed inside the sheet body during storage and handling. When the sheet is bent for application, the nested microneedles are revealed and positioned against the skin, enabling penetration without exposing the needles during normal handling operations.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Object-affected harmful factors

If microneedles are raised from the principal surface by bending the sheet, then safety during handling is improved, but bending resistance deteriorates causing fracture or rupture

Engineering Contradiction:
Improvesafety during handlingVSAvoidbending resistance
Core Design Contradiction:
Object-affected harmful factorsVSStrength

Solution Approach 1:

The invention employs a flexible sheet made of elastomeric material that can undergo bending without fracture. This flexible film structure allows the sheet to be bent into various configurations for microneedle deployment while maintaining structural integrity and preventing rupture, thus enabling safety improvement without sacrificing bending resistance.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The invention utilizes changes in physical parameters of the flexible sheet, particularly its elastic properties and bending radius, to enable microneedle exposure. By controlling the bending parameters within specific ranges, the sheet can reveal microneedles for skin application while avoiding excessive stress that would cause fracture or rupture.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If microneedles are formed along the principal surface, then manufacturing simplicity is improved, but microneedle exposure and penetration capability deteriorates

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidmicroneedle penetration capability
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The invention transitions from a static microneedle configuration (where needles are fixed in position) to a dynamic configuration where microneedles can change their exposure state. The microneedles are arranged along the principal surface but are designed to become exposed through the dynamic action of bending the flexible sheet, thus maintaining manufacturing simplicity while achieving penetration capability.

Inventive Principle:
Principle #15Dynamics

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

Ensures safe handling and effective bending resistance, allowing the microneedle sheet to be safely stored and applied without risk of fracture or rupture, while providing efficient administration of active components.

Implementation Method 1

such a microneedle sheet is required to have bending resistance so that fracture, cracks, rupture or the like will not occur in the sheet even when the sheet is bent

Methodology Applied
Scientific EffectBending resistance:

Implementation Method 2

the microneedles are raised from the principal surface by bending the sheet, and the raised microneedles pierce skin

Methodology Applied
Scientific EffectBending:

Data Source

PatentEP3508247B1Microneedle sheet
Publication Date: 2024.08.14 HISAMITSU PHARM CO INC
  • EP3508247B1 patent drawingFigure 1

AI summary

A microneedle sheet is disclosed that comprises a plurality of microneedles formed on a sheet generally along a principal surface of the sheet, wherein the microneedles contain a water-soluble polysaccharide and water, the water content is 1 mass% or more and less than 19 mass% based on the total mass of the microneedles, and the microneedles are raised from the principal surface by bending the sheet.