Stretchable Electrode Liquid Level Sensor for Non-Flat Surfaces

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Solution Overview

Problem

Conventional non-contact capacitive liquid level sensors are limited to flat surfaces due to their rigid construction, making them ineffective for use on non-flat surfaces such as round containers, and they require direct contact with the liquid, which can lead to corrosion and damage from vapors or foam.

Innovation Solution

A stretchable electrode layer with a Young's modulus of less than 100 megapascals, allowing the sensor to conform to non-flat surfaces and operate non-contactly, using electroactive polymers and a layered design that includes a first and second stretchable receiver electrode and a transmitter electrode, enabling wireless data transmission for remote monitoring.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional non-contact capacitive liquid level sensors are used, then they can operate without direct contact with liquid, but they are limited to flat surfaces due to rigid construction

Engineering Contradiction:
Improvesurface adaptabilityVSAvoidsurface shape limitation
Core Design Contradiction:
Adaptability or versatilityVSShape

Solution Approach 1:

The sensor employs a flexible printed circuit board (FPC) as the substrate for mounting electrodes, replacing rigid circuit boards. This flexible substrate can be bent and conform to non-flat surfaces such as cylindrical containers, enabling the sensor to adapt to various surface geometries while maintaining its non-contact capacitive sensing functionality

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The sensor design incorporates a flexible, bendable structure that can dynamically adapt to different surface shapes during installation. The FPC substrate allows the sensor to be physically deformed into different configurations to match the target surface geometry, transforming a static rigid structure into a dynamically adaptable one

Inventive Principle:
Principle #15Dynamics

2Reliability

If contact sensors are used, then liquid level can be measured, but the sensor comes into contact with liquid causing corrosion and damage

Engineering Contradiction:
Improvesensor durabilityVSAvoidcorrosion and damage from liquid contact
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The sensor uses capacitive coupling through the container wall as an intermediary medium to sense liquid level without direct contact. The electric field penetrates the container wall to detect changes in dielectric constant caused by liquid presence, allowing measurement while maintaining physical isolation from corrosive liquid environments

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention replaces mechanical contact-based sensing with non-contact capacitive sensing. Instead of physical electrodes touching the liquid, the system uses electric field interaction through the container wall to detect liquid level, eliminating mechanical wear and chemical corrosion issues

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

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 can effectively measure liquid levels on non-flat surfaces without direct contact, preventing corrosion and damage, and allows for remote monitoring, reducing manual checks and enabling automated refilling processes.

Implementation Method 1

measuring a capacitance between a transmitter electrode and a receiver electrode

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 2

A stretchable transmitter electrode can be configured to generate an electric field, and a stretchable receiver electrode can be configured to detect the electric field

Methodology Applied
Scientific EffectElectric Field: Electric Field

Data Source

PatentEP3887775B1Non-contact, remotely-monitored, level sensor system
Publication Date: 2023.10.25 PARKER HANNIFIN CORP
  • EP3887775B1 patent drawingFigure 1
  • EP3887775B1 patent drawingFigure 2
  • EP3887775B1 patent drawingFigure 3

AI summary

An example liquid level sensor is described. The liquid level sensor includes a first layer, a stretchable electrode layer provided on the first layer, and a second layer provided on the stretchable electrode layer. The stretchable electrode layer includes a first stretchable receiver electrode and a stretchable transmitter electrode. The liquid level sensor can include an electrical connector for coupling the liquid level sensor to a computing device. The computing device can be configured to determine a liquid level within the container and wirelessly transmit data indicative of the liquid level.