Organic Liquid Sensor With Variable Resistance Material

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Solution Overview

Problem

Existing sensors for detecting organic liquids, such as hydrocarbon fuels, face challenges in accurately and reliably detecting leaks from storage tanks, as they may not effectively indicate the presence of organic liquids at varying heights or in mixed environments with water, leading to potential contamination and environmental hazards.

Innovation Solution

A sensor system comprising an elongate non-conductive substrate with variable resistance material and conductive filler, where the presence of an organic liquid causes the material to swell, altering the electrical resistance between electrodes, allowing for detection of organic liquids at any point along the sensor surface, even in indeterminate positions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a sensor uses a single sensor surface design, then the structure is simple, but it cannot reliably detect organic liquids at varying heights or in mixed environments with water

Engineering Contradiction:
Improvedetection reliabilityVSAvoidsensor structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The sensor is divided into two separate sensor surfaces: a first sensor surface exposed to detect organic liquids and a second sensor surface not exposed to detect water or other substances. This segmentation allows each surface to specialize in detecting specific substances, improving overall detection reliability in mixed environments while maintaining a relatively simple overall structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the sensor have different properties: the first sensor surface has properties optimized for organic liquid detection (e.g., hydrophobic coating), while the second sensor surface has properties optimized for water detection (e.g., hydrophilic coating). This local differentiation enables reliable detection in varying environments without requiring complex additional components.

Inventive Principle:
Principle #3Local quality

2Measurement precision

If the sensor material swells upon contact with organic liquid, then detection sensitivity is improved, but the material expansion may cause structural deformation

Engineering Contradiction:
Improvedetection sensitivityVSAvoidstructural stability
Core Design Contradiction:
Measurement precisionVSStability of the object's composition

Solution Approach 1:

The sensor utilizes a flexible diaphragm structure that can accommodate the swelling of the sensor material when it contacts organic liquid. The diaphragm's flexibility allows it to deform elastically in response to material expansion, maintaining structural integrity while enabling the swelling-based detection mechanism to function effectively.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The sensor exploits the change in physical parameters (swelling) of the sensor material upon organic liquid contact as the detection mechanism. By designing the sensor to measure resistance changes caused by this swelling while accommodating the physical expansion through flexible structures, the system achieves high detection sensitivity without compromising structural stability.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If the sensor uses conductive filler in swellable matrix, then the resistance change signal is enhanced, but the manufacturing precision becomes more difficult to control

Engineering Contradiction:
Improveresistance signal precisionVSAvoidmaterial composition control
Core Design Contradiction:
Measurement precisionVSManufacturing precision

Solution Approach 1:

The sensor employs a composite material consisting of a swellable polymer matrix embedded with conductive filler particles. This composite structure enhances the resistance change signal when the matrix swells upon organic liquid contact, improving detection precision. The manufacturing challenges are addressed through established composite material processing techniques that can control filler distribution and concentration.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The sensor design leverages the parameter change (resistance) that occurs when the swellable matrix absorbs organic liquid and expands. The conductive filler within the matrix creates a percolation network whose electrical properties change predictably with matrix swelling, providing a strong detection signal. Manufacturing precision is maintained by controlling the initial filler loading and distribution in the composite material formulation.

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 sensor system provides reliable and accurate detection of organic liquids by measuring resistance changes, enabling effective monitoring of organic liquid presence in diverse environments, including those with varying liquid levels and mixed substances, thereby preventing contamination.

Implementation Method 1

the variable resistance material of the sensor surfaces contacted by the organic liquid may have a relatively high resistance... When an organic liquid is present at a liquid level height sufficient to contact at least a portion of the sensor surfaces, the portion of the variable resistance material of the sensor surfaces contacted by the organic liquid may have a relatively high resistance

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Implementation Method 2

The sensor surfaces may be formed from a variable resistance material, the concentration of which may be provided to produce a first resistance when the matrix material is in an un-swelled condition... The conductive pathway through the sensor surfaces and the bridging electrode may have a first resistance when the sensor surfaces are in contact with an organic liquid

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP1955377B1Sensor for detecting organic liquids
Publication Date: 2017.08.16 PENTAIR THERMAL MANAGEMENT LLC
  • EP1955377B1 patent drawingFigure 1~3
  • EP1955377B1 patent drawingFigure 4
  • EP1955377B1 patent drawingFigure 5~6

AI summary

A sensor for detecting the presence of an organic liquid. The sensor includes an a elongate substrate having a first and second opposed surface, and a first sensor surface disposed on at least a portion of the first surface of the substrate and a second sensor surface disposed on at least a portion of the second surface of the substrate. The sensor also includes a bridging electrode electrically coupling the first and second sensor surfaces, a first electrode disposed on the first surface of the substrate and electrically coupled to the first sensor surface, and a second electrode disposed the second surface of the substrate and electrically coupled to the second sensor surface.