Heterostructure Thermal Fluid Flow Sensor with 2D Carrier Gas
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Solution Overview
Problem
Existing thermal fluid flow sensors face issues with high power dissipation, low sensitivity, and slow dynamic response due to inadequate thermal isolation of the heated element, mechanical fragility, and vibration sensitivity, particularly in silicon-based membrane structures.
Innovation Solution
A micro-machined heterostructure-based sensor utilizing a two-dimensional carrier gas within a membrane structure, providing enhanced thermal isolation, sensitivity, and reliability through superior temperature coefficient of resistance and resistance to electromigration, with a membrane configuration that reduces power dissipation and improves thermal dynamics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional silicon-based membrane structures are used for thermal isolation, then thermal isolation is provided, but mechanical fragility and vibration sensitivity increase
Solution Approach 1:
The patent employs a composite membrane structure consisting of multiple layers including silicon nitride, silicon dioxide, and sacrificial oxide layers. This composite structure provides both effective thermal isolation to reduce power dissipation and enhanced mechanical strength to eliminate fragility and vibration sensitivity issues associated with single-material silicon membranes.
2Loss of energy
If heated element thermal isolation is improved using conventional methods, then power dissipation is reduced, but sensitivity and dynamic response deteriorate
Solution Approach 1:
The patent segments the membrane structure into distinct functional layers: a thermal isolation layer (silicon nitride and silicon dioxide) beneath the heated element, and a sacrificial oxide layer for release. This segmentation enables the heated element to be thermally isolated from the substrate while maintaining controlled thermal coupling to the fluid, thereby reducing power dissipation without sacrificing sensitivity or dynamic response.
3Loss of energy
If membrane thickness is increased for better thermal isolation, then power dissipation decreases, but response time slows down
Solution Approach 1:
The patent optimizes the thickness parameters of the membrane layers to achieve the desired balance. The silicon nitride layer is configured with a specific thickness range that provides sufficient thermal isolation to reduce power dissipation while maintaining thin enough dimensions to ensure fast thermal response time. This parameter optimization allows simultaneous achievement of low power consumption and fast dynamic response.
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 low power consumption, high sensitivity, and fast response while providing multi-directional, multi-range, and multi-properties sensing capabilities, including fluid flow rate, direction, temperature, and type, with enhanced reliability in harsh environments.
Implementation Method 1
The sensor achieves low power consumption, high sensitivity, and fast response while providing multi-directional, multi-range, and multi-properties sensing capabilities
Implementation Method 2
anemometric sensors measure the convective heat transfer induced by fluid flow passing over a heated element
Implementation Method 3
a heating resistor and a heater temperature sensing diode integrated on a silicon membrane
Data Source
AI summary
We disclose herewith a heterostructure-based sensor comprising a substrate comprising an etched portion and a substrate portion; a device region located on the etched portion and the substrate portion; the device region comprising at least one membrane region which is an area over the etched portion of the substrate. At least one heterostructure-based element is located at least partially within or on the at least one membrane region, the heterostructure-based element comprising at least one two dimensional (2D) carrier gas.