Bolometer Array for Fluid Flow Direction and Speed Detection
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Solution Overview
Problem
Bolometer sensors are primarily used for measuring electromagnetic radiation and temperature, but they lack the capability to effectively detect fluid flow characteristics such as direction and speed, which is essential for various applications beyond simple radiation sensing.
Innovation Solution
A fluid flow sensor system comprising a reference bolometer and multiple sensing bolometers, where the reference bolometer is configured to block infrared radiation and the sensing bolometers allow it to detect temperature changes caused by fluid flow, enabling the determination of flow direction and speed by analyzing the temperature gradients and absorption signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If bolometer sensors are used for measuring electromagnetic radiation and temperature, then radiation detection capability is improved, but fluid flow detection capability is lost
Solution Approach 1:
The sensor array is divided into multiple independently controllable bolometer elements, with at least one element having different infrared transmissivity than others. This segmentation allows different elements to serve different functions (radiation detection vs. fluid flow detection) simultaneously, resolving the contradiction between specialized radiation detection and versatile fluid flow detection capability.
Solution Approach 2:
Different regions of the sensor array are assigned different properties - some bolometer elements are configured to be opaque to infrared radiation while others are transparent. This local differentiation enables the sensor to detect both radiation (using opaque elements) and fluid flow (using transparent elements) without compromising either capability.
2Measurement precision
If bolometer sensors detect temperature changes caused by fluid flow, then fluid flow detection is improved, but sensitivity to external infrared radiation is reduced
Solution Approach 1:
The sensor array segments bolometer elements into those with different infrared transmissivity characteristics. Elements designed for fluid flow detection are made infrared-transparent to allow detection of temperature changes from flowing fluid, while elements with infrared opacity block external radiation interference, thus resolving the contradiction between fluid flow detection sensitivity and radiation interference rejection.
Solution Approach 2:
The sensor array acts as an intermediary system that can selectively transmit or block infrared radiation to different elements. By controlling which elements receive radiation and which detect fluid flow temperature changes, the system mediates between the harmful effect of external radiation and the useful detection of fluid flow characteristics.
3Measurement precision
If a single bolometer configuration is used for radiation measurement, then radiation detection accuracy is improved, but multi-parameter sensing capability is reduced
Solution Approach 1:
The sensor array implements multi-functionality by configuring different bolometer elements with different infrared transmissivity properties. This allows a single unified sensor structure to perform multiple functions: detecting electromagnetic radiation, measuring fluid flow direction, determining fluid temperature, and detecting flow speed - thus achieving universality that resolves the contradiction between specialized accuracy and multi-parameter capability.
Solution Approach 2:
The system adds a new dimension of control by varying the infrared transmissivity property across different bolometer elements. This dimensional differentiation in material properties enables the sensor array to simultaneously measure multiple parameters (radiation intensity, fluid flow direction, temperature) that would otherwise require separate sensor systems.
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 system effectively determines fluid flow direction and speed by detecting temperature changes and gradients, providing accurate flow characteristics without being affected by external radiation, thus expanding the applicability of bolometer sensors beyond radiation measurement.
Implementation Method 1
an absorber configured to absorb infrared radiation within the cavity
Implementation Method 2
A bolometer is a type of sensor used to measure electromagnetic radiation. A bolometer generally comprises an absorptive element that is connected via a thermal link to a heat sink or thermal reservoir
Implementation Method 3
the cap structure configured to block infrared radiation from entering the cavity from outside the cap structure
Implementation Method 4
A thermometer or other temperature sensitive element is attached to or embedded into the absorptive element in order to measure a temperature of the absorptive element
Implementation Method 5
determining a flow characteristic of a fluid that flows near the reference bolometer and the plurality of sensing bolometers based on the reference signal and the measurement signals
Data Source
AI summary
The sensor comprises a reference bolometer and a plurality of sensing bolometers. Each sensing bolometer is arranged adjacent to the reference bolometer. Each bolometer comprises (i) a substrate, (ii) a cap structure connected to the substrate, the cap structure configured to define a cavity between an inner surface of the cap structure and a first surface of the substrate, (iii) an absorber connected the substrate and arranged within the cavity, the absorber configured to absorb infrared radiation within the cavity, and (iv) a readout circuit connected to the absorber and configured to provide a signal that indicates an amount of infrared radiation absorbed by the absorber. The cap structure of the reference bolometer blocks infrared radiation from entering the cavity from outside the cap structure. The cap structure of each sensing bolometers allows infrared radiation to enter the cavity from outside the cap structure.