Cladded Waveguide for Surgical Illumination

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Solution Overview

Problem

Conventional surgical illumination systems face challenges with heat buildup, weight, and inefficient light transmission due to the use of incandescent and semiconductor lighting, leading to excessive heating and poor illumination quality, especially when using waveguides made from materials like PMMA and polycarbonates, which suffer from frustrated total internal reflection (TIR) losses.

Innovation Solution

A surgical illumination system utilizing a non-fiber optical waveguide with an optical cladding layer of at least 350 nanometers thickness, made from materials like fluoroacrylate or polytetrafluoroethylene, to prevent evanescent waves from coupling to the environment, ensuring efficient light transmission and minimizing heat buildup.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional waveguide materials (PMMA, polycarbonates) are used, then the waveguide can be manufactured with existing materials, but light transmission efficiency deteriorates due to frustrated total internal reflection losses

Engineering Contradiction:
Improvelight transmission efficiencyVSAvoidmaterial selection flexibility
Core Design Contradiction:
Loss of energyVSEase of manufacture

Solution Approach 1:

The patent applies composite materials by combining a waveguide core made from conventional materials (PMMA or polycarbonate) with an optical cladding layer made from fluoropolymer materials (fluoroacrylate or polytetrafluoroethylene). This composite structure allows the core to maintain manufacturing compatibility while the cladding layer provides superior optical properties that prevent frustrated TIR losses, thereby resolving the contradiction between ease of manufacture and light transmission efficiency.

Inventive Principle:
Principle #40Composite materials

2Illumination intensity

If overhead illumination with high intensity incandescent or semiconductor lighting is used, then the surgical field can be illuminated, but heat buildup occurs causing unwanted coagulation of blood and heating of patient's body

Engineering Contradiction:
Improvesurgical field illuminationVSAvoidheat buildup
Core Design Contradiction:
Illumination intensityVSTemperature

Solution Approach 1:

The patent replaces the conventional overhead illumination system (incandescent or semiconductor lighting) with a waveguide-based illumination system that delivers light directly to the surgical field. This substitution eliminates the heat-generating light sources from the overhead position, thereby resolving the contradiction between achieving sufficient illumination intensity and preventing harmful heat buildup in the surgical field and patient body.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Illumination intensity

If overhead illumination systems are used, then the surgical field can be illuminated, but shadows are created in the illuminated body cavity or surgical field

Engineering Contradiction:
Improvesurgical field illuminationVSAvoidshadow creation
Core Design Contradiction:
Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the overhead illumination system with a waveguide-based system that positions the light source within or near the surgical field. This substitution allows light to be delivered from multiple angles and directly to the target area, eliminating shadow creation while maintaining illumination intensity, thereby resolving the contradiction between these two parameters.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Device complexity

If conventional waveguide materials are used, then the waveguide can be integrated with surgical instruments, but light leakage occurs due to evanescent wave coupling to the environment

Engineering Contradiction:
Improvewaveguide integrationVSAvoidlight leakage
Core Design Contradiction:
Device complexityVSLoss of energy

Solution Approach 1:

The patent applies composite materials by adding an optical cladding layer of fluoropolymer material around the conventional waveguide core. This cladding layer creates a lower refractive index boundary that prevents evanescent wave coupling to the surrounding environment, thereby eliminating light leakage while maintaining the integration capability of the waveguide with surgical instruments.

Inventive Principle:
Principle #40Composite materials

5Loss of energy

If thick optical cladding layer is added to prevent light leakage, then light transmission efficiency improves, but device complexity and manufacturing difficulty increase

Engineering Contradiction:
Improvelight transmission efficiencyVSAvoidwaveguide structure
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The patent specifies a precise parameter for the cladding layer thickness (at least 350 nanometers) to achieve the optimal balance between preventing light leakage and maintaining manufacturing feasibility. This parameter optimization resolves the contradiction by providing a specific thickness that is sufficient to prevent evanescent wave coupling while remaining practical for manufacturing processes.

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 system provides improved light conduction and reduced heat-related issues, maintaining illumination quality and comfort during lengthy procedures by preventing light leakage and heat accumulation, thus enhancing surgical field illumination.

Implementation Method 1

The optical cladding has a thickness of at least 350 nm to thereby prevent evanescent waves of conducted light from coupling to the environment surrounding the waveguide

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP3685734B1Medical device featuring cladded waveguide
Publication Date: 2022.03.09 INVUITY INC
  • EP3685734B1 patent drawingFigure 1A~1C
  • EP3685734B1 patent drawingFigure 1D~1E
  • EP3685734B1 patent drawingFigure 2~3

AI summary

Various surgical devices having integrated means of illuminating a surgical field are provided. Retractors, cannulas, suction devices and the like are disclosed having integrated optical waveguides coupleable to external lighting sources. The waveguides feature cladding layers configured to enhance transmission efficiency.