Flexible Sheet Sensor for Accurate Edema Measurement

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Solution Overview

Problem

Existing edema measurement apparatuses struggle to accurately measure pitting edema, as the band may bite into the limb, causing indentation and inaccurate readings.

Innovation Solution

A measurement apparatus featuring a sensor that freely expands and contracts, capable of detecting changes in electrical characteristics, is used to measure edema while minimizing indentation, employing a sheet-shaped sensor with elastomer material and conductive layers, and a support member that surrounds the limb to suppress indentation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If an elongated band is wound around the limb to measure circumferential length, then the measurement can be performed, but the band may bite into the limb causing indentation and inaccurate measurement

Engineering Contradiction:
Improveedema measurement accuracyVSAvoidindentation on limb
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent employs a sheet-shaped sensor made of elastomer material that can flexibly conform to the limb surface without rigid structures. This flexible film approach allows the sensor to adapt to the limb's contours while maintaining contact, preventing the band from biting into the limb and causing indentation, thus resolving the contradiction between measurement precision and avoiding harmful mechanical contact.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent replaces traditional mechanical band-based measurement systems with an electrical sensing system. The sheet-shaped sensor detects edema through electrical characteristic changes (such as capacitance or resistance) rather than relying on mechanical circumferential measurement, eliminating the mechanical pressure that causes indentation while maintaining measurement capability.

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

2Stability of the object's composition

If a rigid band is used to ensure stable contact with the limb, then contact stability is improved, but indentation and discomfort increase

Engineering Contradiction:
Improvecontact stabilityVSAvoidindentation on limb
Core Design Contradiction:
Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The patent uses a flexible sheet-shaped sensor made of elastomer material that maintains stable contact with the limb through its elasticity and conformability. The flexible film adapts to the limb's shape and maintains consistent electrical contact without the rigidity that causes indentation, achieving both contact stability and comfort simultaneously.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent changes the mechanical parameters of the contact interface by using soft elastomer material instead of rigid bands. The material's flexibility and ability to deform elastically allow it to maintain stable contact pressure while avoiding excessive local stress that would cause indentation, thus resolving the contradiction between stability and comfort.

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 apparatus accurately measures edema by detecting capacitance changes, reducing indentation and improving measurement precision.

Implementation Method 1

a sensor (110) that freely expands and contracts in one direction (expansion-contraction direction X1) that intersects a thickness direction (Y1) and is capable of detecting change in an electrical characteristic in association with expansion or contraction

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 2

a sensor (110) that freely expands and contracts in one direction (expansion-contraction direction X1) that intersects a thickness direction (Y1)

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3777678B1Measurement device
Publication Date: 2022.10.26 TERUMO KK
  • EP3777678B1 patent drawingFigure 1
  • EP3777678B1 patent drawingFigure 2~3
  • EP3777678B1 patent drawingFigure 4A~4B

AI summary

[Problem] To provide a measurement apparatus that can measure the amount of edema of a limb more accurately. [Solution] A measurement apparatus 100 according to the present invention is a measurement apparatus capable of measuring the amount of edema of an ankle B1. The measurement apparatus includes a sensor 110 that has a sheet shape and freely expands and contracts in one direction X1 that intersects a thickness direction Y and is capable of detecting change in an electrical characteristic in association with expansion or contraction, and a support member 120 that is attached to both end portions 110a and 110b in the expansion-contraction direction in the sensor and surrounds the ankle together with the sensor in a mounted state in which the measurement apparatus is mounted on the ankle.