Electrostatically Formed Nanowire Gas Sensor
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Solution Overview
Problem
The fabrication of nanowires for gas sensing applications is complicated and not reproducible, particularly when implemented on hot plates, leading to trade-offs in performance.
Innovation Solution
The development of Electrostatically Formed Nanowires (EFN) with a quasi-nanowire structure, featuring multiple gates and a sensing area on a silicon substrate, which allows for improved gas sensitivity through controlled depletion regions and efficient conductivity changes in response to gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional nanowire fabrication methods are used, then gas sensing capability is achieved, but fabrication complexity increases and reproducibility deteriorates
Solution Approach 1:
The patent replaces complex mechanical nanowire fabrication processes with electrostatic field-based formation. Instead of using mechanical deposition or assembly methods that are difficult to reproduce, the invention uses controlled electrostatic fields to form nanowires, substituting mechanical complexity with controllable electrical field effects.
Solution Approach 2:
The invention changes the formation parameter from mechanical process variables to electrostatic field parameters (voltage, field distribution). This parameter transformation enables precise control and reproduction of nanowire formation by adjusting electrical parameters rather than complex mechanical settings.
2Adaptability or versatility
If nanowires are implemented on hot plates for gas sensing, then sensing function is achieved, but fabrication reproducibility worsens
Solution Approach 1:
The patent performs preliminary electrostatic formation of nanowires before implementing them on hot plates. This preliminary action creates well-defined nanowire structures with controlled properties, ensuring that subsequent deployment on hot plates for gas sensing starts from a reproducible baseline rather than requiring precise hot plate fabrication.
Solution Approach 2:
The invention separates the nanowire formation process from the hot plate implementation. Nanowires are formed independently through electrostatic methods, then transferred or integrated onto hot plates. This segmentation allows each component to be optimized and reproduced independently, improving overall manufacturing precision.
3Reliability
If conventional nanowire fabrication is used, then gas sensing is achieved, but device parameter spread increases
Solution Approach 1:
The patent replaces mechanical fabrication variability with electrostatic field control. By using electric fields to form nanowires, the process achieves more uniform parameters across devices since electrostatic fields can be precisely controlled and reproduced, reducing the spread in device parameters compared to mechanical methods.
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
EFN provides enhanced gas sensing capabilities with improved reproducibility and reduced device parameter spread, enabling efficient detection of multiple gases with increased sensitivity and reduced noise.
Implementation Method 1
the sensing area configured to, in reaction to a predefined substance, cause a change in a conductivity of the conductive channel
Implementation Method 2
heavily doping the silicon substrate with a second type of silicon dopant using the hard mask to form a wire region... by forming first and second lateral-gate areas on both surfaces of the wire region
Data Source
AI summary
For example, an Electrostatically Formed Nanowire (EFN) may include a source region; at least one drain region; a wire region configured to drive a current between the source and drain regions via a conductive channel; a first lateral-gate area extending along a first surface of the wire region between the source and drain regions; a second lateral-gate area extending along a second surface of the wire region between the source and drain regions; and a sensing area in opening in a backside of a silicon substrate under the wire region and the first and second lateral-gate areas, the sensing area configured to, in reaction to a predefined substance, cause a change in a conductivity of the conductive channel.