Asymmetric Electrode Plasma Generation for Liquid Analysis

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Solution Overview

Problem

Existing analytical systems for elemental composition analysis of liquids, such as inductively coupled plasma optical emission spectroscopy, face issues with clogging due to dirt and solid particles, complex bubble dynamics, and poor signal-to-noise ratios, leading to inadequate sensitivity and precision, especially in industrial and online applications.

Innovation Solution

An apparatus with a chamber filled with electrically conductive liquid and electrodes where the conductive contact area of the first electrode is smaller than the second, allowing controlled ionization and plasma generation without a separate gas input, maintaining a constant ionized bubble position for precise optical radiation analysis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a narrow portion tube is used to generate plasma, then plasma generation is achieved, but dirt and solid particles accumulate blocking liquid flow

Engineering Contradiction:
Improveplasma generationVSAvoidclogging by dirt and solid particles
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention removes the narrow portion tube structure from the system and replaces it with electrodes of different surface areas in direct contact with the liquid. This extraction eliminates the clogging problem while maintaining plasma generation capability through direct liquid contact between electrodes.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention introduces an asymmetric electrode configuration where the larger electrode serves as an intermediary that distributes liquid flow evenly, preventing particle accumulation while the smaller electrode generates the plasma discharge in the liquid medium.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If bubble dynamics are used for plasma generation, then plasma is produced, but bubble position and dimensions vary causing measurement errors

Engineering Contradiction:
Improveplasma productionVSAvoidmeasurement accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The invention replaces the mechanical bubble formation process with direct electrical discharge between asymmetric electrodes in liquid contact. This substitution eliminates bubble dynamics variability and provides a stable, controllable plasma source for precise optical emission spectroscopy measurements.

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

3Reliability

If thermal spark type discharge plasma is used, then plasma generation occurs, but excessive background noise results

Engineering Contradiction:
Improveplasma generationVSAvoidbackground noise
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The invention changes the discharge parameters by using asymmetric electrode areas in direct liquid contact, which modifies the plasma generation mechanism to produce less background noise while maintaining effective plasma for spectroscopic analysis.

Inventive Principle:
Principle #35Parameter changes

4Reliability

If precise chamber shaping is implemented, then plasma generation is improved, but manufacturing cost increases

Engineering Contradiction:
Improveplasma generationVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The invention removes the complex chamber shaping requirements and replaces them with a simple asymmetric electrode configuration. This extraction simplifies the manufacturing process while maintaining plasma generation effectiveness, reducing the need for expensive precision tooling.

Inventive Principle:
Principle #2Taking out (Extraction)

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 solution eliminates the need for specific chamber shapes, ensures consistent measurement positions, and improves sensitivity and precision by controlling ionization and plasma generation, reducing errors and background noise, thus meeting industrial requirements.

Implementation Method 1

The voltage causes an electric current through the liquid and forms a gaseous bubble of the vaporized liquid in the narrow portion. The high voltage between the electrodes then causes electric discharge through the bubble which generates plasma in the bubble. In the plasma the molecules are decomposed into atoms which excite to higher energy states.

Methodology Applied
Scientific EffectIonization: Ionisation

Implementation Method 2

When the atoms return to lower energy states they emit optical radiation which is specific to the elements and which can be analysed by a spectrometer, for example.

Methodology Applied
Scientific EffectOptical emission: Luminescence

Data Source

PatentEP3391031B1Apparatus and method for optically detecting the emissions of a plasma produced in a conductive liquid by means of two electrodes having areas of different size in contact with the liquid
Publication Date: 2021.11.10 UNIV OF OULU
  • EP3391031B1 patent drawingFigure 1~2
  • EP3391031B1 patent drawingFigure 3~4
  • EP3391031B1 patent drawingFigure 5~7

AI summary

An apparatus comprises: a chamber (100) configured to be filled with electrically conductive liquid (102); a first electrode (104) and a second electrode (106) located within the chamber (100); an optical radiation receiver (126); and an electrically conductive contact area (108) of the first electrode (104) and an electrically conductive contact area (110) of the second electrode (106) are configured to be in contact with the liquid (102) of the chamber (100) wherein the electrically conductive contact area (108) of the first electrode (104) is configured to be smaller than the electrically conductive contact area (110) of the second electrode (106). The first electrode (104) and the second electrode (106) are configured to receive electric energy and output the electric energy to the liquid (102) in order to cause substance of the liquid (102) to emit optical radiation at the electrically conductive contact area (108) of the first electrode (104) on the basis of densification of the electric energy due to the smaller electrically conductive contact area (108) of the first electrode (104). The optical radiation receiver (126) is configured to receive the optical radiation for analysis of the liquid (102).