Capacitive Fluid Level Sensor Electrode Integration

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Solution Overview

Problem

Existing fluid level detection systems for containers are costly, inaccurate, and unreliable, especially for removable and portable containers, due to issues with electrode contact and air gaps, which hinder high-resolution measurements.

Innovation Solution

Integrating electrodes into the container design using membrane switch technologies with conductive coatings and adhesive backings, and optionally incorporating RFID tags for precise capacitance measurements and data tracking, allowing for secure and consistent contact without moving parts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If external plates or electrodes are used for capacitance level sensing, then fluid level detection capability is provided, but measurement accuracy and reliability deteriorate due to air gaps between the container and electrode

Engineering Contradiction:
Improvefluid level measurement accuracyVSAvoidmeasurement reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The electrode is merged with the container structure by integrating it into the container wall or lid. This eliminates the air gap between the electrode and the container, ensuring consistent electrical contact and reliable capacitance measurements. The electrode becomes an integral part of the container rather than an external component.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

A conductive adhesive or conductive coating is used as an intermediary between the electrode material and the container surface. This intermediary ensures secure electrical contact and maintains consistent coupling between the electrode and the container wall, eliminating air gaps and improving measurement reliability.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If traditional fluid level detection methods are used, then detection capability is provided, but cost increases and measurement accuracy becomes questionable

Engineering Contradiction:
Improvefluid level detection accuracyVSAvoidmanufacturing cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The electrode is implemented as a thin, inexpensive conductive coating or printed circuit trace on the container surface rather than using expensive bulk metal electrodes. This approach significantly reduces material costs while maintaining adequate functionality for the application.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent replaces complex mechanical level sensing mechanisms with a simple capacitance-based electrical sensing system. This substitution reduces manufacturing complexity and cost while improving measurement accuracy and reliability.

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

3Measurement precision

If removable containers are placed on instruments for fluid amount determination, then measurement capability is provided, but time is added to time-sensitive procedures

Engineering Contradiction:
Improvefluid amount measurement capabilityVSAvoidprocedure throughput
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The container itself performs the sensing function through its integrated electrode, eliminating the need for external measurement instruments. The container autonomously provides capacitance data that can be read by the instrument, removing the step of placing the container on a separate measurement device and improving workflow efficiency.

Inventive Principle:
Principle #25Self-service

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

This approach provides accurate, reliable, and cost-effective fluid level detection with high precision, enabling real-time monitoring and data recording, including changes in fluid levels and container history.

Implementation Method 1

capacitance level sense of fluids has a strong technical foundation, since fluids (particularly water) have a much higher dielectric constant as compared to air or vacuum, and yield a strong signal

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 2

fluids (particularly water) have a much higher dielectric constant as compared to air or vacuum

Methodology Applied
Scientific EffectDielectric constant: Dielectric Permittivity

Data Source

PatentEP3092465B1Fluid containers with integrated level sensing
Publication Date: 2021.02.24 SIEMENS HEALTHCARE DIAGNOSTICS INC
  • EP3092465B1 patent drawingFigure 1A
  • EP3092465B1 patent drawingFigure 1B
  • EP3092465B1 patent drawingFigure 2

AI summary

Electrodes are integrated into a container design for fluid level detection in the container. The electrodes have a conductive surface, and an adhesive backing may be attached opposite the conductive surface to secure the electrodes to the container. Electrical contact to each conducting surface is made to a detection circuit to obtain a fluid level. A radio-frequency identification (RFID) tag may be incorporated onto the container along with the level detection circuit to record the container history, such as last used time event, net evaporation during storage, re-suspension performance after storage, number of agitation cycles, instrument serial number, date opened/accessed, and other desirable information.