Plasma Generation via Conductive Liquid in Microfluidic Channels

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Solution Overview

Problem

Conventional methods for generating plasma in microfluidic systems face challenges such as contamination from electrodes, high gas and power consumption, and difficulty in miniaturization, which hinder high-sensitivity elemental analysis in applications like μTAS and lab-on-a-chip.

Innovation Solution

A method and apparatus that utilize a narrow portion in an insulation material flow channel with a significantly smaller cross-sectional area than the main channel, where a conductive liquid is filled and an electric field is applied to generate plasma, reducing contamination and enabling miniaturization while maintaining performance comparable to ICP optical emission spectrometers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If electrodes are inserted into solution to generate plasma, then plasma can be generated without nebulizer, but impurities from electrodes contaminate the plasma

Engineering Contradiction:

Improveelimination of nebulizerVSAvoidelectrode impurity contamination

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

The invention extracts the harmful solid electrode from the plasma generation system and replaces it with a conductive liquid that serves as the plasma medium itself. The conductive liquid is introduced into the flow channel and subjected to electric field to generate plasma, eliminating the source of impurity contamination while maintaining plasma generation capability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention introduces a conductive liquid as an intermediary substance that mediates between the electric field and plasma generation. This conductive liquid acts as a bridge, allowing electric field application without requiring solid electrodes that would contaminate the plasma. The conductive liquid can be easily replaced or flushed to maintain purity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If conventional plasma generation methods are used in microfluidic systems, then plasma can be generated, but gas consumption and power consumption are high

Engineering Contradiction:

Improveplasma generation capabilityVSAvoidgas and power consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The invention changes the physical parameters of the plasma generation system by using a conductive liquid medium instead of gas, and by applying electric field directly to the liquid in a micro-scale flow channel. This parameter change enables plasma generation at lower power consumption and without requiring large volumes of gas flow, thus reducing both gas and power consumption while maintaining reliable plasma generation.

Inventive Principle:

Principle #35Parameter changes

3Stability of the object's composition

If conventional plasma generation methods are used, then plasma can be generated stably, but the apparatus cannot be miniaturized

Engineering Contradiction:

Improveplasma stabilityVSAvoidapparatus size

Core Design Contradiction:

Stability of the object's compositionVSVolume of moving object

Solution Approach 1:

The invention transitions from three-dimensional plasma generation in gas to two-dimensional plasma generation in a planar microfluidic flow channel. By confining the conductive liquid and electric field application to a micro-scale planar geometry, the system achieves miniaturization while maintaining plasma stability through controlled fluid flow and electric field distribution in the reduced dimensional space.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 allows for the generation of plasma with minimal impurity contamination, achieving miniaturization, reducing gas and power consumption, and enabling high-sensitivity elemental analysis, making it suitable for portable and cost-effective on-site analysis of polluted samples.

Implementation Method 1

applying an electric field to the narrow portion to conduct the electric field through the narrow portion, thereby generating plasma at the narrow portion

Methodology Applied

Scientific EffectPlasma generation: Plasma

Implementation Method 2

applying an electric field to the narrow portion to conduct the electric field through the narrow portion

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS7875825B2Plasma generating equipment

Publication Date: 2011.01.25 MICRO EMISSION

AI summary

A method for generating plasma and a method for elemental analysis, each comprising the steps of providing a narrow portion in a flow channel made of an insulation material, the narrow portion having a cross-sectional area markedly smaller than a cross-sectional area of the flow channel; filling the flow channel and the narrow portion with a conductive liquid, and thereafter applying an electric field to the narrow portion, to conduct the electric field through the narrow portion, thereby generating plasma at the narrow portion. An apparatus for generating plasma, the apparatus for generating plasma comprising a narrow portion in a flow channel made of an insulation material, the narrow portion having a cross-sectional area markedly smaller than a cross-sectional area of the flow channel; and a means of applying an electric field to the narrow portion to conduct the electric field through the narrow portion; and an apparatus for emission spectroscopic analysis comprising the apparatus for generating plasma as defined above.