Dynamic Pressure Sensor Venting for Altitude Detection
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Solution Overview
Problem
Conventional absolute pressure sensors have limited sensitivity and resolution, making them inadequate for detecting small altitude changes and pressure variations in applications like indoor navigation and gesture recognition, where small pressure changes correspond to significant altitude changes.
Innovation Solution
A dynamic pressure sensor with a deflectable membrane and a ventilation hole that equalizes pressure between a reference volume and the ambient environment, allowing for increased sensitivity and resolution by sensing pressure changes within a specific frequency range, enabling detection of altitude changes smaller than 1 cm and pressure changes as low as 0.0002 mbar.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sealed reference volume is used in conventional absolute pressure sensors, then the sensor can measure absolute pressure, but the sensitivity and resolution are limited and cannot detect small pressure changes
Solution Approach 1:
The sensor is divided into two functional parts: a sealed reference volume for absolute pressure measurement and a vented reference volume for dynamic pressure measurement. This segmentation allows the sensor to achieve both absolute pressure capability and high sensitivity to small pressure changes by using the vented volume that can equalize with ambient pressure dynamics.
Solution Approach 2:
The invention introduces a dynamic element by allowing one reference volume to be vented to the ambient environment, enabling the reference pressure to dynamically track ambient pressure changes. This dynamic reference allows the sensor to detect small pressure variations that would be imperceptible against a static sealed reference.
2Measurement precision
If the reference volume is sealed to provide a fixed reference pressure, then absolute pressure can be measured, but small altitude changes and pressure variations cannot be detected
Solution Approach 1:
The invention uses a dynamic reference pressure approach where one reference volume is vented to allow pressure equalization with the ambient environment. This dynamic reference tracks altitude changes and pressure variations, enabling detection of small changes while maintaining measurement stability through the venting mechanism.
Solution Approach 2:
The vented reference volume acts as an intermediary between the sealed reference volume and the ambient environment. It mediates the pressure reference by dynamically equalizing with ambient pressure while providing a stable reference for the sensing element, enabling precise detection of pressure changes.
3Measurement precision
If conventional pressure sensing is used, then general pressure measurement is possible, but detection of pressure changes as low as 0.0002 mbar is not achievable
Solution Approach 1:
The sensor uses segmented reference volumes with different venting configurations to create a differential pressure measurement system. This segmentation enables the sensing element to detect very small pressure variations by comparing pressures across the segmented volumes, achieving resolution down to 0.0002 mbar.
Solution Approach 2:
The invention changes the reference pressure parameter from a fixed sealed value to a dynamically adjustable value that can equalize with ambient pressure. This parameter change enables the sensor to adapt to different operating conditions and detect extremely small pressure variations by maintaining an optimized pressure differential across the sensing element.
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 dynamic pressure sensor achieves enhanced sensitivity and resolution, capable of detecting small altitude changes and pressure variations, improving performance in applications such as indoor navigation and gesture recognition by filtering out non-relevant frequency components and focusing on infrasonic range pressure changes.
Implementation Method 1
Many MEMS devices use capacitive sensing techniques for transducing the physical phenomenon into electrical signals. In such applications, the capacitance change in the sensor is converted to a voltage signal using interface circuits.
Implementation Method 2
a ventilation hole configured to equalize an absolute pressure inside the reference volume with an absolute ambient pressure outside the reference volume
Implementation Method 3
A pressure difference between the sealed volume and an external volume, such as the ambient environment in some cases, causes the membrane to deflect.
Data Source
AI summary
According to various embodiments, a dynamic pressure sensor includes a substrate, a reference volume formed in the substrate, a deflectable membrane sealing the reference volume, a deflection sensing element coupled to the membrane and configured to measure a deflection of the membrane, and a ventilation hole configured to equalize an absolute pressure inside the reference volume with an absolute ambient pressure outside the reference volume.