Magnetite Conductive Composition for Low-Noise Pressure Sensing
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Solution Overview
Problem
Existing electrically conductive compositions exhibit large resistance ranges and high noise levels due to field-enhanced quantum tunnelling, which are not adequately addressed by current technologies, and there is a need for a pressure-sensitive composition with a wide working range and low noise.
Innovation Solution
A composition comprising a particularly pure form of magnetite (Fe3O4) with minimal SiO2 content, mixed with particles of different shapes and sizes, and a silicone polymer binder, which allows for controlled resistance changes and reduced noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If void bearing particles are used to achieve field-enhanced quantum tunnelling, then the resistance range is increased, but the noise level increases
Solution Approach 1:
The patent removes voids from the filler particles, extracting the source of field-enhanced quantum tunnelling that causes noise. This is achieved by using solid filler particles without internal cavities, thereby eliminating the harmful noise effect while maintaining electrical conductivity through alternative mechanisms.
Solution Approach 2:
The patent converts the harmful field-enhanced quantum tunnelling effect into a beneficial controlled quantum tunnelling effect. By removing voids and using particles with controlled surface characteristics, the patent achieves quantum tunnelling without the excessive field enhancement that causes noise, effectively turning a harmful phenomenon into a controlled useful one.
2Reliability
If acicular particles are used to reduce start resistance, then the start resistance is reduced, but noise remains due to field-enhanced quantum tunnelling
Solution Approach 1:
The patent uses composite filler particles comprising a magnetic oxide core (providing conductivity and low start resistance) coated with a non-magnetic oxide layer (suppressing field enhancement and noise). This composite structure combines the benefits of both materials to achieve low resistance without excessive noise.
Solution Approach 2:
The patent changes the surface properties of the filler particles by coating them with non-magnetic oxide layers. This parameter change modifies the electrical and magnetic characteristics at the particle surface, reducing field enhancement effects while maintaining the conductive pathway provided by the magnetic oxide core.
3Reliability
If pure magnetite is used to achieve pressure sensitivity, then the pressure sensitivity is enhanced, but the material cost increases
Solution Approach 1:
The patent creates a composite structure with a magnetic oxide core providing pressure sensitivity and a non-magnetic oxide coating providing cost effectiveness and noise reduction. This composite approach maintains the essential magnetic properties needed for pressure sensing while using more abundant, less expensive oxide materials.
Solution Approach 2:
The patent applies different material properties to different parts of the filler particle: the core retains magnetic oxide properties for pressure sensitivity, while the surface coating uses non-magnetic oxide for cost effectiveness and noise reduction. This local differentiation of material quality optimizes both performance and cost.
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 composition achieves a wide resistance range with low noise, sensitivity to pressure changes, and robustness against shear forces, using less costly materials and ensuring safety for human contact.
Implementation Method 1
Quantum tunnelling describes a conduction mechanism which occurs when the inter particle distance decreases such that the insulating barriers between adjacent conductive particles are so thin that quantum tunnelling occurs through the thin insulating barriers.
Implementation Method 2
The presence of spikes and voids in the filler particles amplifies the electric fields within the composites. Large resistance ranges are a consequence of quantum tunnelling. Field-enhanced quantum tunnelling occurs with filler particles that contain voids.
Implementation Method 3
The present invention relates to an electrically conductive composition and in particular to such a composition comprising magnetite in a particulate form.
Data Source
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AI summary
A pressure sensitive electrically conductive composition comprises a contained quantity of magnetite particles, wherein the quantity of magnetite particles includes a distribution of particle sizes between sub-micron and tens of microns, and wherein the magnetite particles have a plurality of planar faces, adjacent planar faces connected at a vertex, the particles each having a plurality of vertices wherein the magnetite particles are irregular in shape and have a low aspect ratio.