Nanowire-Oxide Oxygen Sensing for Fast Low-Temperature Response
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Solution Overview
Problem
Existing oxygen gas sensors, such as those with solid electrolytes and resistance-type oxygen gas sensors, suffer from slow response times at low operating temperatures and insufficient sensitivity, failing to meet industrial needs for speed and sensitivity.
Innovation Solution
A gas sensor combining a nanowire made of a specific metal, such as platinum, with an oxide layer of a high-resistance semiconductor, creating two conduction paths for fast response and high sensitivity to oxygen gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If oxygen gas sensors with solid electrolytes are used, then sensitivity to oxygen gas is achieved, but response time becomes slow (several tens of seconds)
Solution Approach 1:
The patent employs a composite structure combining a nanowire made of a specific metal (platinum, palladium, or rhodium) with an oxide layer made of a high-resistance semiconductor. This composite configuration creates two conduction paths: one through the nanowire and another through the oxide layer, enabling fast response while maintaining sensitivity to oxygen gas.
2Use of energy by stationary object
If resistance-type oxygen gas sensors using oxide semiconductors are used at low operating temperature (around 300 °C), then energy consumption is reduced, but response time increases to several hundred seconds
Solution Approach 1:
The composite structure of metal nanowire and high-resistance semiconductor oxide layer enables the sensor to achieve fast response time even at low operating temperatures (around 300 °C or lower). The dual conduction paths through the nanowire and oxide layer work synergistically to maintain rapid response without requiring high energy input.
3Measurement precision
If the nanowire thickness is reduced to enhance surface scattering effect, then sensitivity to gas detection is improved, but electrical conductivity of the nanowire decreases
Solution Approach 1:
The patent specifies optimal parameter ranges for the nanowire, including thickness of 1 nm or more and 20 nm or less, and length of 80 nm or more and 1 μm or less. These parameter optimizations balance the surface scattering effect (which enhances sensitivity) with sufficient electrical conductivity, resolving the contradiction between sensitivity and reliability.
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 achieves fast response and high sensitivity to oxygen gas, enabling detection even at low operating temperatures and a wide range of concentrations.
Implementation Method 1
creates, in addition to a first conduction path where carriers (such as oxygen vacancies and electrons) pass through the nanowire, a second conduction path where carriers (such as oxygen vacancies and electrons) are injected from the nanowire into the oxide layer, travel through the oxide layer, and return to the nanowire
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 2A~2E
AI summary
To provide a gas sensor with fast response and high sensitivity to oxygen gas. Disclosed is a gas sensor 100 including: a substrate 10; a first pad electrode 12A and a second pad electrode 12B; a nanowire 14 made of a specific metal; and an oxide layer 16 made of a high-resistance semiconductor that is an oxide of a metal different from a metal constituting the nanowire 14. The first pad electrode 12A and the second pad electrode 12B are formed on or above the substrate 10. The nanowire 14 connects the first pad electrode 12A and the second pad electrode 12B and is formed on or above the substrate 10. The oxide layer 16 is formed in contact with the nanowire 14. This contact between the nanowire 14 and the oxide layer 16 provides fast response and high sensitivity to oxygen gas.