LS-APGD Microplasma for Compact Elemental Analysis
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Solution Overview
Problem
Conventional inductively coupled plasma (ICP) sources are large, gas-intensive, and not well-suited for analyzing small sample sizes, particularly in laser ablation applications, where compact, low-power, and cost-effective excitation/ionization sources are needed for elemental analysis.
Innovation Solution
A liquid sampling, atmospheric pressure, glow discharge (LS-APGD) device is developed, featuring a hollow capillary and counter electrode configuration that creates a microplasma for vaporizing, exciting, and ionizing analytes, which can be used in conjunction with a laser ablation device to analyze aerosols containing particulate analytes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inductively coupled plasma (ICP) source is used for excitation/ionization, then reliable elemental analysis is achieved, but device size and gas consumption increase significantly
Solution Approach 1:
The patent extracts the essential excitation/ionization function from the large ICP source and implements it in a compact glow discharge source. The glow discharge source maintains the core analytical capability while reducing device volume by using a different physical principle (glow discharge instead of inductive coupling) that achieves similar results in a smaller footprint.
Solution Approach 2:
The patent changes the operating parameters from ICP conditions (high power, atmospheric pressure, large volume) to glow discharge conditions (lower power, controlled pressure, compact volume). This parameter transformation allows achieving reliable elemental analysis with a significantly reduced source size and lower gas consumption.
2Reliability
If inductively coupled plasma (ICP) source is used for excitation/ionization, then reliable elemental analysis is achieved, but gas consumption increases significantly
Solution Approach 1:
The patent extracts the essential excitation/ionization function from the gas-intensive ICP source and implements it in a glow discharge source that consumes significantly less gas. The glow discharge mechanism achieves plasma formation and analyte excitation with much lower gas flow rates compared to ICP.
Solution Approach 2:
The patent changes the gas consumption parameter from high (ICP) to low (glow discharge) while maintaining analytical reliability. The glow discharge source operates efficiently at lower gas flows, reducing the loss of substance parameter while preserving the core analytical capability.
3Power
If conventional ICP source is used, then excitation/ionization of analytes is achieved, but power consumption is high
Solution Approach 1:
The patent extracts the essential excitation/ionization capability from the high-power ICP source and implements it in a low-power glow discharge source. The glow discharge mechanism achieves the same analytical function with significantly reduced power requirements.
Solution Approach 2:
The patent changes the power consumption parameter from high (ICP) to low (glow discharge) while maintaining excitation/ionization capability. The glow discharge source operates at lower power levels, reducing energy usage while preserving the ability to excite and ionize analytes for detection.
4Ease of operation
If laser ablation produces aerosol with particulate analytes, then direct solid sampling is achieved, but efficient excitation/ionization in compact source is challenging
Solution Approach 1:
The patent uses the glow discharge plasma as an intermediary medium that efficiently couples with laser-ablated aerosols. The glow discharge plasma provides a transition zone where particulate analytes in the aerosol are effectively excited and ionized, bridging the gap between direct solid sampling and reliable detection.
Solution Approach 2:
The patent optimizes the glow discharge parameters (pressure, power, gas flow) to maximize efficiency in exciting and ionizing laser-ablated aerosols. By adjusting these parameters, the system achieves reliable excitation/ionization of particulate analytes while maintaining the compact source design and direct sampling capability.
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 LS-APGD device provides a compact, low-power, and cost-effective means for analyzing small sample sizes, achieving efficient excitation/ionization of nano-sized particles and enabling direct introduction of analytes into a microplasma for precise elemental analysis with reduced gas and liquid consumption.
Implementation Method 1
a glow discharge space, the glow discharge space comprising a space in which a flow discharged from the first hollow capillary intersects a flow discharged from the second hollow capillary
Implementation Method 2
The microplasma of these methods operates at power densities of about 10 W/mm3, much higher than the typically-cited value of about 0.1 W/mm3 for ICP
Implementation Method 3
For analytical purposes, laser ablation has been commonly based on two primary measurement modalities: laser-induced breakdown spectroscopy (LIBS) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS)
Data Source
AI summary
A liquid sampling, atmospheric pressure, glow discharge (LS-APGD) device as well as systems that incorporate the device and methods for using the device and systems are described. The LS-APGD includes a hollow capillary for delivering an electrolyte solution to a glow discharge space. The device also includes a counter electrode in the form of a second hollow capillary that can deliver the analyte into the glow discharge space. A voltage across the electrolyte solution and the counter electrode creates the microplasma within the glow discharge space that interacts with the analyte to move it to a higher energy state (vaporization, excitation, and/or ionization of the analyte).