Pneumatic Granular Body Immobilizer

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Solution Overview

Problem

Existing immobilization devices for body parts during medical imaging, such as CT and MRI, face challenges including complex handling, insufficient immobilization quality, high costs, and the need for custom fabrication, which can result in motion artifacts and discomfort for patients.

Innovation Solution

A reusable immobilization device comprising a bag filled with granular material, such as polystyrene pearls, housed within an outer shell with a hollow space for pressured air, which applies force to the body part for stable positioning, combined with a cast made of composite or thermoplastic material for secure fit and adjustable pressure control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If vacuum pressure is used to immobilize a body part, then immobilization quality is improved, but device complexity and handling difficulty increase

Engineering Contradiction:
Improveimmobilization qualityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies pneumatic pressure through a hollow space between the outer shell and bag, allowing the bag to expand and compress the granular material against the body part. This pneumatic mechanism replaces complex vacuum systems while achieving reliable immobilization through controlled pressure application.

Inventive Principle:
Principle #29Pneumatics and hydraulics

Solution Approach 2:

The patent changes the pressure parameter from vacuum (negative pressure) to positive pressure, simplifying the device architecture. By applying positive pressure through the hollow space, the system achieves effective immobilization without requiring complex vacuum generation and maintenance systems.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If thermoplastic material is heated to become mouldable, then adaptability to body parts is improved, but device complexity and handling difficulty increase

Engineering Contradiction:
Improveadaptability to body partsVSAvoiddevice complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent uses a flexible bag made of elastic material that can be expanded and compressed. The bag's flexibility allows it to adapt to various body part shapes and sizes without requiring heating or molding processes, simplifying the device while maintaining high adaptability.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent employs a dynamic system where the bag can be expanded and compressed as needed. This dynamic adaptability allows the same device to fit different body parts by adjusting the volume and pressure, eliminating the need for thermal molding processes.

Inventive Principle:
Principle #15Dynamics

3Reliability

If custom fabrication is performed for each patient, then immobilization quality is improved, but manufacturing time and cost increase

Engineering Contradiction:
Improveimmobilization qualityVSAvoidmanufacturing time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent designs a universal device that can be used on different body parts and for different patients. The adjustable bag and granular material system provides customized immobilization for each patient without requiring custom fabrication, reducing preparation time while maintaining high immobilization quality.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent uses pre-filled bags with granular material that are ready for immediate use. The device requires only adjustment and pressure application rather than custom fabrication for each patient, significantly reducing preparation time while maintaining effective immobilization.

Inventive Principle:
Principle #10Preliminary action

4Reliability

If granular material is compressed against the body part, then immobilization quality is improved, but patient comfort deteriorates

Engineering Contradiction:
Improveimmobilization qualityVSAvoidpatient comfort
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies controlled pneumatic pressure to compress the granular material, allowing adjustment of the compression level. This controlled parameter adjustment ensures sufficient immobilization force while maintaining patient comfort by avoiding excessive pressure.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The elastic bag acts as a flexible intermediary between the compressed granular material and the patient's body. This flexible shell distributes the pressure evenly and adapts to body contours, maintaining immobilization effectiveness while improving patient comfort compared to direct rigid contact.

Inventive Principle:
Principle #30Flexible shells and thin films

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 device ensures minimal patient movement (less than 50 µm), improves image quality by reducing motion artifacts, is comfortable, easy to handle, and cost-effective, while being suitable for various body parts and imaging modalities without causing pain or pain.

Implementation Method 1

Between the outer shell (10) and the bag (12) there is a hollow space (14) for receiving pressured air in order to produce a force F on the bag (12)

Methodology Applied
Scientific EffectPressured air: Pressure Increase

Implementation Method 2

The reference sign 12 in figure 1 denotes also the layers of the bag (12). The bag (12) is mounted into an outer shell (10). This force F acts on the granular material (15) which itself acts on the part of the body for an immobilizing or fixing

Methodology Applied
Scientific EffectCompression: Compression

Data Source

PatentEP2104477B1Immobilizing device for a part of a body
Publication Date: 2012.02.29 ETH ZURICH
  • EP2104477B1 patent drawingFigure 1
  • EP2104477B1 patent drawingFigure 2~3

AI summary

An immobilizing device (1) for immobilizing a part of a body (2) comprises a) a bag (12) filled with a granular material (15), where the bag (12) is put over the part of a body (2); b) an outer shell (10) in which the bag is mounted; c) between the outer shell (10) and the bag (12) a hollow space (14) is formed for receiving pressured air in order to produce a force (F) on the bag (12) for immobilizing the part of a body. This device (1) has the combined advantages over known devices such as almost no absorption of x-rays; perfect fit for every kind of a part of a body; comfortable for a patient; reusable; cheap; neutral smell; very light; easy application.