Oxygen Sensor Using TiO2 Bridge and Nichrome Wires
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Solution Overview
Problem
Current high temperature oxygen sensors for kilns are expensive, fragile, and have short lifespans due to their delicate construction and corrosive environment, requiring a costly oxygen reference and platinum coating, which limits their durability and operational effectiveness.
Innovation Solution
A rugged oxygen sensor designed with Nichrome series 90 wires and a Titanium Dioxide (TiO2) bridge, eliminating the need for an oxygen reference and platinum, and fabricated using accessible materials, which provides a significant change in resistivity with temperature and oxygen levels, allowing for precise monitoring without the need for a ceramic tube.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current oxygen sensors use zirconium/yttrium with platinum coating and ceramic tube, then measurement precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent extracts and eliminates the oxygen reference component (ceramic tube with platinum) from the sensor structure. The new sensor uses only a working electrode made of ruthenium or ruthenium alloy, removing the need for the reference electrode and its protective ceramic tube, thereby simplifying the overall device structure while maintaining oxygen detection capability
Solution Approach 2:
The patent replaces expensive platinum materials with cheaper ruthenium or ruthenium alloy materials for the working electrode. This substitution significantly reduces material cost while providing sufficient durability for the sensor's operational lifetime in high-temperature kiln environments
2Reliability
If current oxygen sensors use platinum coated wires and ceramic tube, then reliability is improved, but cost increases significantly
Solution Approach 1:
The patent substitutes expensive platinum with cheaper ruthenium or ruthenium alloy materials for the working electrode. Ruthenium provides comparable corrosion resistance and thermal stability in high-temperature kiln atmospheres, achieving reliable operation without requiring significant amounts of precious metal
Solution Approach 2:
The patent employs ruthenium or ruthenium alloy composite materials that combine the benefits of corrosion resistance, thermal stability, and cost-effectiveness. These composite materials provide reliable performance in the harsh corrosive environment of firing kilns while eliminating dependence on expensive platinum
3Measurement precision
If current oxygen sensors use delicate ceramic tube and platinum coating, then measurement precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent removes the delicate ceramic tube and complex platinum coating processes from the manufacturing workflow. The simplified structure using ruthenium working electrode without reference electrode eliminates the need for precise ceramic tube fabrication and complex multi-layer platinum deposition, making manufacturing more accessible and easier to control
Solution Approach 2:
The patent changes the material parameter from platinum to ruthenium or ruthenium alloy, which has different but equally effective electrochemical properties for oxygen sensing. This parameter change simplifies the manufacturing process by eliminating the need for specialized platinum deposition techniques while maintaining measurement precision
4Measurement precision
If current oxygen sensors are exposed to corrosive firing atmosphere, then oxygen detection function is improved, but lifespan decreases due to degradation
Solution Approach 1:
The patent uses ruthenium or ruthenium alloy materials that inherently resist corrosion from hydrocarbon combustion byproducts in kiln atmospheres. This material selection extends sensor lifespan by protecting against degradation from the corrosive environment while maintaining real-time oxygen detection functionality
Solution Approach 2:
The patent employs ruthenium alloy composite materials that combine corrosion resistance with electrochemical activity. These composite materials withstand prolonged exposure to high-temperature corrosive atmospheres, extending operational lifespan while maintaining accurate oxygen monitoring 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 sensor offers a cost-effective, durable solution with minimal temperature-induced resistivity changes, enabling long-term monitoring of kiln atmospheres, reducing maintenance costs and extending sensor lifespan, while providing accurate readings of oxygen levels for precise control of reduction cycles.
Implementation Method 1
a durable oxygen sensor exhibiting a large range of change in resistivity in the working ranges of oxygen from a neutral to a fully reduced kiln atmosphere
Implementation Method 2
a rugged oxygen sensor providing only a minor change in resistivity due to a change in temperature up to 2400 degrees F.
Implementation Method 3
A rugged oxygen sensor designed with Nichrome series 90 wires and a Titanium Dioxide (TiO2) bridge
Data Source
AI summary
An oxygen sensor for a gas, coal, oil or wood fired kiln that is orders of magnitude cheaper than the current state of the art oxygen sensors. It uses a TiO2 tip sintered between and bridging a 1 mm spacing between a pair of 22 gauge Nichrome® series 90 round annealed resistance wires (0.64 mm diameter and having 0.648 Ohms/ft resistance). The Nichrome® 90 wires do not contact each other. One of the wires is a signal wire that resides down the center of an insulating sheath and the other wire is a ground wire that is wound around the outside of a high temperature ceramic insulating sleeve. The sensor needs no temperature compensation and exhibits an approximate 50,000 ohms of resistance change from a neutral (ambient) atmosphere and a fully reduced atmosphere.