Elastomeric Particle Conducting Surface Pressure Sensor Creep
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Solution Overview
Problem
Existing pressure sensors for measuring pressure on body parts suffer from mechanical property mismatches, high sensitivity, infinite quiescent impedance, nonlinearity, poor repeatability, creep, hysteresis, and sensitivity to curvature, temperature, pressure, and humidity, leading to inaccurate measurements.
Innovation Solution
Development of elastomeric particles with a non-conducting elastomeric body and an electrically conducting surface, arranged in a composite material to reduce creep, hysteresis, and electrical aging, and the use of a sensor system comprising these particles and a matrix material to manage strain-related damage and improve mechanical response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive particles are dispersed in an elastomeric matrix, then electrical conductivity is achieved, but strain-related damage and creep increase significantly
Solution Approach 1:
The patent uses a composite material system consisting of conductive particles dispersed in an elastomeric matrix. This composite structure allows the material to exhibit both electrical conductivity (from the conductive particles) and elastic recovery (from the elastomeric matrix), resolving the contradiction between achieving conductivity and maintaining stability under strain.
Solution Approach 2:
The patent modifies the physical and chemical parameters of the composite by varying the type and concentration of conductive particles (carbon black, graphite, metal particles), the elastomeric matrix composition (silicone rubber, polyurethane), and the curing conditions. These parameter changes optimize both the electrical conductivity and the mechanical stability, reducing creep and strain-related damage while maintaining reliable conductivity.
2Measurement precision
If high loading levels are applied to induce finite quiescent impedance, then pressure sensing capability is improved, but viscoelastic properties degrade dramatically
Solution Approach 1:
The patent optimizes the composition parameters including the ratio of conductive particles to elastomeric matrix, the particle size distribution, and the crosslinking density of the elastomer. These parameter adjustments allow the material to achieve finite quiescent impedance for pressure sensing while maintaining stable viscoelastic properties that prevent degradation under loading.
Solution Approach 2:
The elastomeric composite structure provides a balance between conductivity and mechanical properties. The elastomeric matrix maintains viscoelasticity and structural integrity, while the conductive particles provide the necessary electrical pathways for pressure sensing, allowing the material to function at optimal loading levels without degradation.
3Reliability
If conductive coating is provided on elastomeric cells, then electrical conductivity is enhanced, but mechanical properties and repeatability deteriorate
Solution Approach 1:
Instead of coating the elastomeric structure with conductive material, the patent extracts the conductive function to separate discrete particles dispersed within the elastomeric matrix. This separation allows the elastomeric structure to maintain its mechanical integrity and repeatability while the dispersed conductive particles provide the necessary electrical conductivity without compromising mechanical properties.
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 solution provides accurate, precise, and cost-effective pressure measurements on body parts by reducing creep, hysteresis, and electrical aging, while improving mechanical response and sensitivity, and is suitable for contact pressure applications.
Implementation Method 1
an elastomeric particle, comprising a non-conducting elastomeric body having an electrically conducting surface. The conducting surface is organized such that the overall mechanical properties of the particle are governed by the elastomeric body of the particle, while the electrical properties are governed by the conducting surface layer
Data Source
AI summary
An elastomeric particle (1, 1, 1″) comprises a non-conducting elastomeric body (2) having an electrically conducting surface (4a, 4b, 6). Pressure sensor elements (20, 20′, 20″; 30, 30′, 30″, 30′″) comprising such elastomeric particles are disclosed, as well as sensor clusters (50″, 50′″, 50IV, 50V, 50VI, 50VII, 70) comprising such sensor elements. There is also disclosed a pressure sensor element (40, 40′, 40″, 40′″, 40IV, 40V, 40VI, 40VII), comprising a resistive element (44, 44′, 44″) providing a conduction path, a first electrode (42a, 42a-1, 42a-2, 42a-3, 42a-4, 42a-5, 42a-6), connected to the resistive element, a second electrode (42b, 42b′), which in a quiescent state is spaced from said first electrode, wherein the second electrode, when the pressure sensor element is subjected to a pressure, is arranged to contact said first electrode or said resistive element. Systems comprising such sensor elements and sensor clusters are disclosed, as well as methods of their fabrication.