Core-Shell Nanostructure Sensor for Reducing Gas Detection
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Solution Overview
Problem
Current chemical sensors lack sensitivity to detect infinitesimal amounts of reducing gases, such as CO, which are hazardous due to their high adsorptive power and potential to disturb oxygen transfer, leading to safety concerns.
Innovation Solution
A sensor featuring a core-shell nanostructure with a core of oxide semiconductor nanowires and a shell of oxide semiconductor nanoislands, where the shell thickness is adjusted to be equal to or less than the Debye length to form a fully depleted layer, enhancing sensitivity for detecting reducing gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a bulk or thin film semiconductor material is used in the sensing part, then the device structure is simple, but the sensitivity to detect infinitesimal amounts of reducing gas is insufficient
Solution Approach 1:
The sensing part is segmented into a core-shell nanostructure where the core is formed by photolithography and the shell is formed by atomic layer deposition. This segmentation allows each part to contribute differently to the sensing function, with the core providing structural integrity and the shell providing high surface area for gas interaction, thereby achieving high sensitivity while maintaining manufacturability.
Solution Approach 2:
The invention transitions from bulk or thin film (2D/3D) semiconductor materials to a core-shell nanostructure that introduces a new dimensional arrangement. The shell forms a nanoscale layer around the core, creating a high surface-area-to-volume ratio structure that enhances sensitivity to infinitesimal amounts of reducing gas while maintaining a manageable device footprint.
2Measurement precision
If a nanostructured metal oxide is used to increase surface area to volume ratio, then the sensitivity is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The core-shell structure acts as an intermediary between the photolithographically patterned core and the desired nanostructured sensing surface. The core provides a straightforward photolithography-based foundation, while the shell adds the necessary nanoscale surface area. This intermediary approach allows the use of conventional photolithography techniques while achieving nanostructured sensing performance.
Solution Approach 2:
The invention changes the structural parameters of the sensing material by forming a shell with controlled thickness and porosity around the core. This parameter change increases the effective surface area without requiring complete replacement of the manufacturing process with more complex nanofabrication techniques, thus maintaining ease of manufacture while improving sensitivity.
3Measurement precision
If the shell thickness is increased to enhance sensing surface area, then the sensitivity improves, but the conduction channel modulation is reduced
Solution Approach 1:
The invention optimizes the shell thickness parameter to achieve the right balance between sensitivity and conduction channel modulation. By controlling the shell thickness within a specific range, the design maximizes the surface area for gas interaction while maintaining sufficient electron transport through the structure, ensuring both high sensitivity and reliable signal detection.
Solution Approach 2:
The core-shell structure implements local quality differentiation where the core region provides structural support and the shell region provides sensing function. This local differentiation allows each region to be optimized for its specific function - the core for mechanical integrity and the shell for surface area - thereby achieving both high sensitivity and maintained conduction channel modulation.
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 high sensitivity in detecting infinitesimal amounts of reducing gases, preventing hazards by maximizing the modulation of the conduction channel and utilizing a p-n junction and work function difference for improved gas sensing performance.
Implementation Method 1
when a chemical species to be sensed is attached to a surface of the metal oxide, an oxidation-reduction reaction occurs on the surface of the metal oxide to change the electrical resistivity of the metal oxide
Implementation Method 2
an electrical resistivity change of the semiconductor material, which is induced by the density change
Data Source
AI summary
The present invention relates to a sensor including a core-shell nanostructure, and more particularly, to a sensor including: a base material; a sensing part including a core-shell nanostructure that has a core including a first metal oxide and a shell including a second metal oxide formed on the core; and two electrode layers spaced from each other on the sensing part.