Dissolved Oxygen Sensor with Sapphire Window
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Solution Overview
Problem
Existing oxygen sensors, particularly electrochemical sensors, are unsuitable for ultra-high purity environments due to material incompatibility, contamination risks, and disruption of fluid flow, making it difficult to measure sub-part per billion concentrations of dissolved oxygen required in semiconductor and food processing industries.
Innovation Solution
A compact, optically transparent dissolved oxygen sensor with a luminophor attached to a window in the fluid flow path, an optical probe with an excitation and reference light source, and a photodiode, aligned to maintain sensitivity and reduce footprint, using high-strength materials like sapphire or diamond for the window and an annular retainer for sealing, allowing for easy maintenance and minimizing fluid contact with electronic components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrochemical sensors with metal probes are used to measure dissolved oxygen, then oxygen concentration can be measured, but the sensor contaminates the ultra-high purity fluid and disrupts laminar flow
Solution Approach 1:
The patent replaces the electrochemical/mechanical sensor system with an optical sensing system. The optical sensor uses light interaction with a luminophor coating to measure dissolved oxygen concentrations, eliminating the need for metal probes that cause contamination and flow disruption. This substitution enables measurement in ultra-high purity environments while maintaining laminar flow conditions.
Solution Approach 2:
The patent employs a thin luminophor coating applied to an optical window or probe surface. This thin film contains the oxygen-sensitive material without requiring bulk metal construction, allowing the sensor to measure oxygen at sub-part per billion levels while minimizing physical intrusion into the fluid stream and avoiding contamination.
2Measurement precision
If electrochemical sensors are adapted for ultra-high purity environments, then oxygen measurement capability is maintained, but material incompatibility prevents adherence to standards
Solution Approach 1:
The optical sensor system uses chemically inert optical materials (such as sapphire windows, quartz components, and PTFE housings) that do not react with or contaminate ultra-high purity fluids. These inert materials meet semiconductor industry standards (SEMI F57) and FDA requirements, allowing reliable operation in environments where electrochemical sensors with reactive metal components would fail.
Solution Approach 2:
The sensor employs composite construction combining optically transparent materials (sapphire, quartz) with chemically inert polymers (PTFE, PFA) and specialized luminophor coatings. This composite approach achieves both the optical sensitivity required for sub-part per billion detection and the material compatibility needed for ultra-high purity environment certification.
3Area of stationary object
If a compact optical sensor design is used, then footprint is reduced and laminar flow is maintained, but alignment precision of optical components must be maintained
Solution Approach 1:
The patent integrates multiple optical functions (light source, optical path, detection) into a single compact probe assembly. By merging these components into one integrated unit with built-in alignment features, the design reduces overall footprint while ensuring precise optical alignment is maintained during installation and operation, eliminating the need for complex post-installation alignment procedures.
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 solution enables accurate measurement of sub-part per billion oxygen concentrations in ultra-high purity environments without contaminating the fluid or disrupting flow, extending sensor lifespan and reducing maintenance costs by providing an alarm for luminophor replacement and maintaining laminar flow.
Implementation Method 1
a luminophor is attached to the side of the window exposed to the fluid in the flow path. An optical probe includes an excitation light source for illumination of the luminophor
Implementation Method 2
An optical reception guide is configured to conduct light from the luminophor to a photodiode
Data Source
Figure 1~2
Figure 3
Figure 4A
AI summary
Embodiments of a dissolved oxygen sensor are disclosed herein. Embodiments as disclosed herein may include a window of optically transparent material disposed in an opening in a fluid flow path, where a luminophor is attached to the side of the window exposed to the fluid in the flow path. An optical probe may be disposed opposite the window from the fluid flow path on an axis at an angle to the window fluid flow path. The optical probe includes an excitation light source for illumination of the luminophor and a reference light source. An optical reception guide is configured to conduct light from the luminophor to a photodiode adjacent to the end of the optical reception guide distal the window when the luminophor is illuminated by the excitation light source. The optical probe is configured to determine a measure of oxygen concentration of the fluid in the flow path. The optical reception guide and photodiode may be aligned on axis, where the axis may be substantially parallel with the axis on which the optical probe is aligned.