MEMS Pressure Sensor Leakage Path for Accuracy
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Solution Overview
Problem
Conventional MEMS pressure sensors face limitations in sensitivity, accuracy, and durability due to design constraints and physical stresses, leading to inaccurate readings, damage, and high power consumption, especially when measuring atmospheric pressure variations.
Innovation Solution
The introduction of a MEMS pressure sensor system with a back cavity and a membrane connected to the ambient atmosphere through leakage paths, allowing air to flow and measuring the time constant of the membrane's return to its original position to determine pressure, which enhances accuracy and reduces power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sealed cavity is used to measure pressure, then the membrane can detect pressure differences, but the system becomes vulnerable to damage from packaging stress and temperature alterations
Solution Approach 1:
The patent converts the harmful effect of packaging stress and temperature changes into a beneficial calibration mechanism. By allowing controlled leakage of the back cavity through the membrane, the system uses these environmental factors to equalize pressure and establish a reliable reference state, thereby improving both accuracy and durability.
Solution Approach 2:
The patent changes the pressure parameter in the back cavity from a sealed constant value to a dynamically adjustable value. By controlling the leakage rate of the back cavity through the membrane, the system can equalize pressure with the front cavity, transforming the membrane into a pressure-equalizing element rather than a sealed barrier.
2Measurement precision
If the membrane position is used to determine atmospheric pressure, then pressure can be measured, but the system requires frequent recalibration and is sensitive to stress-induced false signals
Solution Approach 1:
The system performs self-calibration by allowing the back cavity to leak and equalize pressure with the front cavity. This automatic pressure equalization eliminates the need for external calibration references and compensates for stress-induced shifts, making the sensor self-regulating and reducing operational complexity.
Solution Approach 2:
The patent implements a feedback mechanism where the leakage rate of the back cavity is monitored and adjusted. By controlling the leakage process, the system maintains pressure equilibrium between the front and back cavities, providing continuous feedback that compensates for environmental variations and stress effects.
3Measurement precision
If a rigid sealed structure is used, then the membrane can be positioned absolutely, but the maximum pressure sensing capability is limited by membrane mechanical strength
Solution Approach 1:
The patent transitions from a static sealed structure to a dynamic pressure-equalizing system. By allowing controlled leakage between the front and back cavities, the membrane can dynamically adjust to pressure differences, extending the sensing range beyond the limits imposed by rigid sealed structures and membrane mechanical strength.
4Measurement precision
If conventional MEMS pressure sensors are used, then pressure can be measured, but sensitivity and frequency response are limited by design and packaging constraints
Solution Approach 1:
The patent divides the pressure sensing function into two separate cavities (front and back) with controlled leakage between them. This segmentation allows each cavity to serve a specific function: the front cavity senses pressure while the back cavity provides a reference state. By separating these functions, the system achieves improved sensitivity and frequency response without being constrained by packaging geometry.
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
This approach improves the accuracy of pressure measurement and reduces power consumption by leveraging the time constant associated with the membrane's movement, effectively addressing the limitations of conventional sensors.
Implementation Method 1
A pressure difference between the sealed cavity and the atmosphere cause a deformation of the membrane
Implementation Method 2
Determining the deformation of the membrane can include determining a change in capacitance
Implementation Method 3
a leakage path (e.g., vent holes) that fluidly connects the ambient atmosphere and the back cavity
Implementation Method 4
As the membrane is allowed to return to an original position or a position of rest, a time constant associated with allowing the membrane to enter a position of rest can be measured
Data Source
AI summary
Microelectromechanical systems (MEMS) pressure sensors having a leakage path are described. Provided implementations can comprise a MEMS pressure sensor system associated with a back cavity and a membrane that separates the back cavity and an ambient atmosphere. A pressure of the ambient atmosphere is determined based on a parameter associated with movement of the membrane.