Suspended Nanowire Thermal Flow Sensor with AC Heating
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Solution Overview
Problem
Existing thermal flux sensors face challenges in minimizing external phenomena such as temperature drifts and Flicker Noise, and are complex to manufacture, with a need for reduced size and simpler construction for integration with microelectronics.
Innovation Solution
A thermal flux sensor using suspended nanowires with dynamic heating and voltage measurement capabilities, employing alternating current for heating and voltage variation detection, decoupling excitation and detection to reduce sensitivity to external drifts and incorporating multiple nanowires for enhanced heat transfer characterization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the sensor size is reduced to facilitate integration, then the sensor can be integrated with microelectronics and application areas increased, but Flicker Noise increases
Solution Approach 1:
The patent applies periodic action by using dynamic heating with alternating current that switches between two states (first and second states) at a specific frequency. This periodic heating pattern allows the sensor to operate at frequencies where Flicker Noise is reduced, thereby maintaining reliability while using miniaturized nanowire structures for sensor integration
2Measurement precision
If conventional thermal flux sensors are used, then temperature measurement can be achieved, but sensitivity to external temperature drifts and phenomena outside the sensor increases
Solution Approach 1:
The patent implements dynamics by transitioning from static to dynamic heating operation. The nanowire is heated dynamically by alternating current that switches between two states, enabling the sensor to differentiate between actual temperature changes and external drifts through frequency-based detection, thereby improving measurement precision while reducing sensitivity to external phenomena
Solution Approach 2:
The patent uses periodic action through dynamic heating at a specific frequency. By heating the nanowire alternately in two states and measuring voltage variations at the same frequency, the system can distinguish genuine temperature measurements from external drifts, reducing sensitivity to temperature drifts and environmental phenomena
3Ease of operation
If static heating is used in thermal flux sensors, then simple operation is achieved, but the sensor cannot eliminate external phenomena such as temperature drifts
Solution Approach 1:
The patent applies periodic action by using dynamic heating with alternating current that switches between two states at a specific frequency. This periodic operation enables the sensor to eliminate external phenomena such as temperature drifts while maintaining ease of operation through automated frequency-based measurement protocols
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-resolution temperature measurement, reduces Flicker noise through high-frequency excitation signals, and is compatible with CMOS technology for integration with microelectronics, effectively characterizing heat transfers in gas environments.
Implementation Method 1
dynamic heating refers to the application of an alternating electric current of a given period
Implementation Method 2
the variation in voltage due to the variation in the electrical resistance of the nanowire which results from the variation over time of the temperature of the nanowire
Implementation Method 3
heat flux sensor, which can be used for measuring the concentration of a gas or TCD sensor or for measuring very low pressures, thus forming a Pirani gauge
Data Source
Figure 1~3
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Figure 6~7B
AI summary
A thermal flow sensor comprising at least one first element (2) suspended with respect to a support, said first suspended element (2) being of an electrically conductive material, first means (6) for biasing said suspended element (2) and first means (8) for measuring the variation of the electric voltage at the terminals of the suspended element (2), said first suspended element (2) being formed by a nanowire and said first biasing means (6) are formed by an alternating current source the intensity of which provides heating of the first suspended element (2) by Joule effect.