Integral Liquid Applicator with Variable Wall Thickness

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Solution Overview

Problem

Existing liquid applicators for surgical prep are messy, offer little control over solution application, and are often complex or cumbersome to use, with prior designs either requiring multipart constructions or using rigid materials for efficiency but resulting in awkward designs.

Innovation Solution

A one-part liquid applicator with a lever integrally formed with the hollow body, featuring a hinge, grip, and foot, where the wall thickness is reduced in the crush region to minimize the force required to fracture a frangible ampoule, and a pad with alternating peaks and troughs to control fluid distribution and prevent pooling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If rigid materials are used for the hollow body to maintain mechanical integrity, then strength is improved, but ease of operation deteriorates due to increased force requirements for crushing the ampoule

Engineering Contradiction:
Improvemechanical integrityVSAvoidforce required to fracture ampoule
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The hollow body is constructed with non-uniform wall thickness, featuring a thicker handle region for structural integrity and a thinner crush region for easier ampoule fracture. This local variation in material distribution allows the same rigid material to provide both strength and ease of operation without compromising overall mechanical integrity.

Inventive Principle:
Principle #3Local quality

2Ease of operation

If the wall thickness is reduced in the crush region to minimize force requirements, then ease of operation is improved, but strength deteriorates in that region

Engineering Contradiction:
Improveforce required to fracture ampouleVSAvoidwall strength in crush region
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The wall thickness is strategically varied along the hollow body, with the crush region having reduced thickness to lower the force required for ampoule fracture. The thicker handle region compensates for this local reduction, maintaining overall structural integrity while enabling easier operation.

Inventive Principle:
Principle #3Local quality

3Device complexity

If a one-part integral construction is used for the lever and hollow body, then device complexity is reduced, but manufacturing precision requirements increase

Engineering Contradiction:
Improvenumber of partsVSAvoidintegral formation accuracy
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The lever and hollow body are formed as a single integral piece through injection molding, eliminating the need for separate components and assembly operations. This merging of parts reduces device complexity and eliminates potential failure points from connections, while the molding process inherently accommodates the required precision for the lever's hinge and foot features.

Inventive Principle:
Principle #5Merging (Combining)

4Force

If the lever is designed with tapered trusses to concentrate force, then force efficiency is improved, but device complexity increases

Engineering Contradiction:
Improveforce concentration at crush pointVSAvoidlever structure complexity
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The lever's trusses are designed with tapered cross-sections that vary the width along their length, concentrating force at the foot where the ampoule crush occurs. This parameter variation in the lever geometry optimizes force efficiency while the overall lever structure remains a simple integral component, balancing force concentration with manufacturing simplicity.

Inventive Principle:
Principle #35Parameter changes

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 design allows for efficient and controlled application of antiseptic solutions with reduced force requirements and improved usability, maintaining mechanical integrity while preventing unintended dripping and shard penetration.

Implementation Method 1

an elongated ampule formed of a frangible material and containing the liquid to be applied

Methodology Applied
Scientific EffectFracture: Fracture Mechanics

Implementation Method 2

a porous element secured to said body and closing off said open end thereof, such that liquid flows through said element when said ampule is fractured

Methodology Applied
Scientific EffectPorosity: Porosity

Data Source

PatentEP2841144B1Liquid applicator
Publication Date: 2017.12.20 3M INNOVATIVE PROPERTIES CO
  • EP2841144B1 patent drawingFigure 1~2
  • EP2841144B1 patent drawingFigure 3~4a
  • EP2841144B1 patent drawingFigure 4b~5

AI summary

Liquid applicators for applying a liquid to a surface. The applicators include a lever having a hinge, grip and foot integrally formed with a hollow body suitable for receiving a liquid-filled ampoule. The foot is positioned adjacent the ampoule and crushes the ampoule when the lever is depressed.