Branched LIBS Spectrometry for Reproducible Trace Element Analysis
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Solution Overview
Problem
Current methods for elemental composition analysis, such as LIBS, face challenges with variability in plasma plume generation and are not suitable for reliable analysis of liquid samples due to issues like droplet formation and light interference, while traditional techniques like ICP-OES require complex setups and generate hazardous waste, limiting their applicability for rapid field measurements.
Innovation Solution
A compact, portable LIBS apparatus that uses a pulsed laser to generate a plasma plume in both solid and liquid samples, with an optical system for precise light collection and detection, and a system computer for automated sample positioning and data analysis, enabling accurate and reproducible measurement of major and trace elements without sample preparation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ICP-OES is used for multi-element analysis, then detection sensitivity and element coverage are improved, but device complexity, operational cost, and environmental harm increase due to complex sample preparation, sophisticated equipment, hazardous chemical waste, and high power requirements
Solution Approach 1:
The patent extracts the essential function of element detection from the complex ICP-OES system by using laser-induced breakdown spectroscopy (LIBS) which requires minimal sample preparation and no hazardous chemicals. The laser ablation process directly vaporizes and excites sample material, eliminating the need for acid digestion, quartz glassware, and complex sample introduction systems while maintaining multi-element detection capability
Solution Approach 2:
The patent changes the fundamental operating parameters from thermal plasma (ICP-OES) to laser-induced plasma (LIBS). This parameter change reduces power consumption from ~3kW to significantly lower levels, eliminates hazardous chemical waste by replacing acid digestion with laser ablation, and simplifies the overall system architecture while preserving detection sensitivity for multiple elements
2Ease of operation
If traditional LIBS is used for solid sample analysis, then portability and ease of operation are improved, but measurement precision deteriorates due to excessive variability in plasma plume generation
Solution Approach 1:
The patent implements feedback control by using a position sensor to detect changes in sample site height caused by laser ablation. The system computer receives this feedback signal and automatically adjusts the stage position to maintain the sample site at the optimal focal distance, ensuring consistent plasma plume generation and high measurement reproducibility across multiple analyses
Solution Approach 2:
The patent performs preliminary positioning and focusing adjustments before each laser ablation measurement. The triangulation sensor pre-locates the sample surface position, and the system computer pre-adjusts the stage or laser focus to ensure the plasma plume forms at the optimal position for spectral collection, thereby eliminating variability before the measurement begins
3Adaptability or versatility
If LIBS is applied to liquid sample analysis, then versatility is improved, but measurement precision deteriorates due to droplet formation and light interference from liquid surfaces
Solution Approach 1:
The patent uses periodic pulsed laser ablation on liquid samples, where each laser pulse creates a fresh plasma plume from the liquid surface. The pulsed nature of the laser allows the plasma to form and cool between pulses, minimizing droplet interference and allowing consistent spectral measurements to be obtained from liquid samples through repeated periodic analysis
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 apparatus provides rapid, accurate, and sensitive elemental analysis of both solid and liquid samples with high reproducibility, reducing operational costs and environmental impact by eliminating the need for hazardous chemicals and complex equipment, and allowing for real-time monitoring in various industries.
Implementation Method 1
A pulsed laser is focused on a sample site to generate a plasma plume during a laser ablation process
Implementation Method 2
The plasma plume can be detected with an optical spectrometer having an intensified charge coupled device
Data Source
AI summary
Apparatus for laser induced ablation spectroscopy (LIBS) is disclosed. An apparatus can have a computer, a pulsed laser and a lightguide fiber bundle that is subdivided into branches. One branch can convey a first portion of the light to a first optical spectrometer and a different branch can convey a second portion of the light to another optical spectrometer. The first spectrometer can be relatively wideband to analyze a relative wide spectral segment and the other spectrometer can be high dispersion to measure minor concentrations. The apparatus can further comprise an unbranched lightguide fiber bundle to provide more light to a low sensitivity spectrometer. The apparatus can include an inductively coupled plasma mass spectrometer ICP-MS and a computer instructions operable to provide normalized LIBS/ICP-MS composition analyses.