Electrochemical Sensor for Trace Organic Contaminant Detection
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Solution Overview
Problem
Current methods for detecting organic contaminants in low oxygen concentration environments, such as those in the semiconductor manufacturing industry, are costly and inefficient, particularly in the parts per trillion (ppt) range, and struggle to differentiate between harmless and harmful hydrocarbons, leading to inaccurate monitoring and equipment failures.
Innovation Solution
A solid-state oxygen anion conductor-based electrochemical sensor with a measurement electrode for catalyzing organic contaminant adsorption and a reference electrode for oxygen dissociation, allowing for temperature-controlled adsorption and titration to quantify organic contaminants by measuring the potential difference across the cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mass spectrometry or gas chromatography is used to detect ppt levels of TOC, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the core detection function from complex mass spectrometry systems by using a simple electrochemical sensor that directly measures organic contaminants through oxidation current, eliminating the need for vacuum systems, gas chromatography columns, and complex data processing while maintaining ppt-level detection precision
Solution Approach 2:
The patent employs inexpensive electrochemical sensors that can be easily replaced rather than using expensive, complex instruments requiring maintenance and specialized operation, significantly reducing both equipment cost and operational complexity while achieving the required measurement precision
2Measurement precision
If mass spectrometry or gas chromatography is used for TOC monitoring, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The electrochemical sensor performs self-diagnosis and automatic calibration by monitoring its own performance parameters, eliminating the need for specialized operators to perform complex maintenance, calibration, and data interpretation procedures required by mass spectrometry and gas chromatography systems
3Ease of operation
If SnO2-based sensors are used in vacuum environments, then ease of operation is improved, but reliability deteriorates
Solution Approach 1:
The patent changes the operating parameters by using an electrochemical sensor that operates at elevated temperatures (200-400°C) in vacuum environments, which prevents the reduction of the oxide layer that plagues SnO2 sensors at lower temperatures, thereby maintaining both operational simplicity and long-term stability
4Productivity
If conventional sensors are used to monitor organic contaminants, then productivity is improved by continuous monitoring, but measurement precision deteriorates due to inability to differentiate hydrocarbon types
Solution Approach 1:
The patent applies local quality by using multiple electrochemical sensors with different selectivity characteristics (different electrode materials, catalysts, or operating conditions) to detect specific hydrocarbon types separately, allowing continuous monitoring while maintaining the ability to differentiate between harmful and harmless hydrocarbons
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 provides a low-cost, semi-quantitative method for monitoring trace organic contaminants in the ppt range, avoiding interference from non-reactive hydrocarbons and offering accurate, point-of-use analysis, thus reducing equipment failures and operational costs.
Implementation Method 1
the measurement electrode comprising material for catalysing the dissociative adsorption of the organic contaminant molecule
Implementation Method 2
the measurement electrode comprising material for catalysing the dissociative adsorption of the organic contaminant molecule
Implementation Method 3
an electrochemical cell comprising a solid state oxygen anion conductor in which oxygen anion conduction occurs at or above a critical temperature Tc
Implementation Method 4
a reference electrode formed on a second surface of the conductor for exposure to a reference environment, the reference electrode comprising material for catalysing the dissociation of oxygen to oxygen anions
Implementation Method 5
a reference electrode formed on a second surface of the conductor for exposure to a reference environment, the reference electrode comprising material for catalysing the dissociation of oxygen to oxygen anions
Implementation Method 6
an electrochemical cell comprising a solid state oxygen anion conductor in which oxygen anion conduction occurs
Data Source
AI summary
An organic contaminant molecule sensor is described for use in a low oxygen concentration monitored environment. The sensor comprises an electrochemical cell, which is formed from a measurement electrode coated with (or formed from) a catalyst having the ability to catalyse the dissociative adsorption of the organic contaminant molecule, the electrode being positioned for exposure to the monitored environment, a reference electrode coated with (or comprised from) a catalyst selected for its ability to catalyse the dissociation of oxygen to oxygen anions, the reference electrode being positioned within a reference environment, and a solid state oxygen anion conductor disposed between and bridging the measurement and reference electrodes, wherein oxygen anion conduction occurs at or above a critical temperature, Tc. Sealing means are provided for separating the reference environment from the monitored environment. Means are also provided for controlling and monitoring the temperature of the cell, and for controlling the electrical current (Ip) flowing between the reference and measurement electrodes. At temperatures (Tads) below Tc, organic contaminant molecules are adsorbed onto and dissociated at the surface of the measurement electrode leading to the build up of carbonaceous deposits at the surface thereof. At temperatures (Ttit) above Tc, an electrical current (Ip) is passed between the reference and measurement electrode thereby to control the number of oxygen anions passing from the reference electrode to the measurement electrode to oxidise the carbonaceous deposits formed at the surface thereof and the formation of carbon dioxide.