Capacitive Sensor for Inflatable Mattress Pressure Regulation

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Solution Overview

Problem

Existing pressure sensors for regulating inflation in inflatable-cell support devices, such as therapeutic mattresses, are costly, bulky, and heavy, limiting their utility, especially in hospital settings where they are needed to prevent bedsores in immobile patients.

Innovation Solution

A capacitive pressure sensor with a flat condenser comprising a compressible dielectric insulating material between conductive layers, designed to be thin, flexible, and inexpensive, providing high sensitivity and rapid signal stabilization, allowing for precise regulation of air pressure in mattresses without the drawbacks of previous technologies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional pressure sensors are used for regulating inflation in inflatable-cell support devices, then measurement precision and reliability are improved, but device complexity, manufacturing cost, and weight increase

Engineering Contradiction:

Improvepressure measurement precisionVSAvoidsensor structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical pressure sensing systems with a capacitive sensing mechanism. The sensor uses a flexible substrate with conductive traces forming a capacitor that changes capacitance in response to pressure-induced deformation of the overlying membrane, eliminating the need for complex mechanical elements while maintaining measurement precision

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs a flexible substrate and thin film structure to create a pressure sensor that is both thin and lightweight. The flexible substrate supports a membrane that deforms under pressure, and this deformation is detected by capacitive elements formed on the substrate, achieving accurate pressure measurement without bulky components

Inventive Principle:

Principle #30Flexible shells and thin films

2Measurement precision

If traditional pressure sensors are used for regulating inflation in inflatable-cell support devices, then measurement precision is improved, but manufacturing cost increases

Engineering Contradiction:

Improvepressure measurement precisionVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent changes the measurement parameter from mechanical displacement or force to electrical capacitance. This allows the use of standard flexible printing techniques to create conductive patterns on the substrate, significantly reducing manufacturing cost while maintaining measurement precision through capacitive detection of membrane deformation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite structures combining flexible substrate materials with conductive inks or coatings. This combination enables the sensor to be manufactured using flexible printing techniques rather than expensive rigid sensor fabrication processes, reducing manufacturing cost while maintaining measurement capabilities

Inventive Principle:

Principle #40Composite materials

3Reliability

If traditional pressure sensors are used for regulating inflation in inflatable-cell support devices, then reliability is improved, but weight increases

Engineering Contradiction:

Improvesensor reliabilityVSAvoidsensor weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent uses thin film structures for the sensor components, including a flexible substrate and thin membrane layers. This reduces the sensor weight significantly compared to traditional rigid pressure sensors while maintaining reliability through the capacitive detection mechanism that is inherently stable and repeatable

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 capacitive sensor effectively distinguishes weight variations down to 1 kg, maintains linearity up to 120 kg, and stabilizes quickly, enabling efficient regulation of air pressure in mattresses while being lightweight and cost-effective, suitable for widespread medical use.

Implementation Method 1

The sensor comprises at least one capacitive cell comprising a flat condenser comprising a layer of compressible dielectric insulating material interposed between two layers of conductive material

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

a flat condenser comprising a layer of compressible dielectric insulating material interposed between two layers of conductive material

Methodology Applied

Scientific EffectDielectric compression: Compression

Data Source

PatentUS8598893B2Pressure sensor comprising a capacitive cell and support device comprising said sensor

Publication Date: 2013.12.03 HILL ROM INDS

AI summary

A sensor for detecting and measuring a load pressure applied to a support device comprises at least one capacitive cell including a flat condenser comprising at least one layer of a compressible insulating dielectric material interposed between two layers of conductive material. A support device capable of supporting the body of a person comprises at least one top layer composed of a plurality of air-filled inflatable cells communicating with inflation elements, characterized in that it comprises a sensor, of which said condenser is disposed under said top layer and connected to an electronic control and regulation device capable of controlling inflation or deflation elements.