Hot-Wire Anemometer Sensor With Wire-Bonded Loops
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Solution Overview
Problem
Existing fluid flow sensors, particularly hot-wire anemometers, face challenges in manufacturing cost, fragility, and performance in open environments, with wire-type sensors being expensive and fragile, and film-type sensors requiring large substrate area and struggling in certain environments.
Innovation Solution
A fluid flow sensor design featuring a substrate with pre-formed wire loops attached via wire bonding, which acts as a sensing element, offering a cost-effective, robust, and low-power solution for accurate fluid flow measurements, suitable for various applications including unmanned vehicles and weather monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wire-type anemometers use a thin wire stretched between two prongs, then the sensing element can be exposed to the fluid being measured, but the device becomes expensive to manufacture and fragile to handle
Solution Approach 1:
The patent replaces the traditional stretched wire configuration with a thin film deposited on a substrate. The thin film sensing element is more robust and durable while maintaining the hot-wire anemometry measurement capability, directly resolving the contradiction between measurement precision and device fragility
Solution Approach 2:
The patent creates a film-type version that replicates the functionality of wire-type anemometers but with improved mechanical properties. The thin film copying the wire's sensing function provides both measurement accuracy and enhanced durability
2Reliability
If film-type anemometers use a thin metal film directly deposited on an electrically insulated substrate, then the device becomes more robust and durable, but they may require a large amount of area on the substrate
Solution Approach 1:
The patent transitions from planar wire configurations to three-dimensional wire loop structures that extend away from the substrate surface. This vertical dimensionality change allows compact sensing elements that reduce the horizontal substrate area requirement while maintaining robustness
Solution Approach 2:
The sensing element is segmented into discrete wire loops rather than requiring a continuous large-area film. This segmentation allows the sensing function to be concentrated in compact three-dimensional structures, reducing the overall substrate area needed
3Measurement precision
If wire-type anemometers use a tightly stretched wire configuration, then the wire can be exposed to the fluid being measured, but the small wire diameter makes the devices expensive to manufacture
Solution Approach 1:
The patent adopts wire bonding technology, a standard, cost-effective manufacturing process from the semiconductor industry. This replaces expensive custom wire stretching and mounting operations with a proven, scalable bonding process that significantly reduces manufacturing cost
Solution Approach 2:
The patent leverages the universality of wire bonding technology, which is already a standard process in IC packaging. This multi-functional approach allows the same manufacturing infrastructure to produce both electronic interconnections and sensing elements, eliminating the need for specialized expensive wire handling equipment
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 provides accurate fluid flow readings, even at low flow rates, is lightweight, and consumes minimal power, while being easy to manufacture and compatible with IC packaging processes, enhancing its durability and performance across different environments.
Implementation Method 1
The invention relates generally to fluid flow sensors and, more particularly, to fluid flow sensors that utilize hot-wire anemometry
Data Source
AI summary
A fluid flow sensor that utilizes hot-wire anemometry and is a small, light weight, cost effective, easily manufactureable, and low power consuming device. The fluid flow sensor operates by exposing a hot wire loop to a fluid stream such that the amount of heat lost to fluid convection is a function of one or more fluid-related parameters (e.g., fluid speed, fluid type, fluid density, etc.). The heat loss affects the resistance in the wire loop, which can then be used to estimate the fluid speed or other fluid-related parameter. According to an exemplary embodiment, the fluid flow sensor includes one or more wire loops that are made from pre-formed wires and are wire bonded, micro-welded or otherwise non-monolithically attached to a substrate that may or may not include embedded sensor circuitry.