Ring Oscillator Pressure Sensor with Electret Bias
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Solution Overview
Problem
Conventional pressure sensors utilizing viscous drag face challenges in reducing power consumption and incorporating squeeze film damping, leading to increased size due to the need for additional damping mechanisms.
Innovation Solution
A pressure sensor design featuring a ring-like oscillator supported by beams, with electret films on electrodes, utilizing alternating current voltage to generate oscillations and detect pressure through squeeze film damping, eliminating the need for direct current bias voltage and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a comb driving mechanism is used to drive the movable electrode, then the pressure sensor can detect pressure utilizing viscous drag of gas, but a high direct current bias voltage must be applied in addition to alternating current voltage, resulting in high power consumption
Solution Approach 1:
The patent extracts and eliminates the direct current bias voltage component from the power supply system. By using only alternating current voltage to drive the comb electrodes, the design removes the continuous power consumption associated with maintaining a DC bias, while still achieving effective pressure detection through the alternating current-driven viscous drag mechanism.
Solution Approach 2:
The patent employs periodic alternating current voltage to drive the comb electrodes instead of continuous direct current. The alternating current creates periodic electrostatic forces that generate the necessary viscous drag effect for pressure detection, converting a continuous power consumption problem into a periodic action that consumes less energy while maintaining detection functionality.
2Measurement precision
If the movable comb electrode is driven in the insertion/removal direction relative to the fixed comb electrode, then pressure detection is achieved, but squeeze film damping cannot be utilized and a separate damping mechanism is required, increasing device size
Solution Approach 1:
The patent merges the pressure detection function with the squeeze film damping function into a single integrated structure. The same comb electrode configuration that enables pressure detection through viscous drag also provides squeeze film damping when the electrodes are arranged with gaps, eliminating the need for a separate damping mechanism and reducing overall device size.
Solution Approach 2:
The comb electrode structure serves multiple functions simultaneously: it acts as both the pressure detection element (through viscous drag) and the damping element (through squeeze film damping). This multi-functional design eliminates redundant components and reduces the overall sensor size while maintaining both detection precision and damping performance.
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 solution achieves lower power consumption and smaller sensor size by using electret films to generate the necessary bias voltage, enabling efficient pressure detection with improved sensitivity and noise tolerance.
Implementation Method 1
electret films that are formed on either one of opposite surfaces of the ring-like oscillator and the electrodes
Implementation Method 2
a pressure sensor utilizing viscous drag of gas
Implementation Method 3
squeeze film damping having a higher damping effect
Data Source
AI summary
A pressure sensor includes: a fixed part; a ring-like oscillator that is supported on the fixed part by a plurality of support beams; a plurality of electrodes that are provided on the fixed part and arranged in an oscillating direction of the ring-like oscillator with a gap; electret films that are formed on either one of opposite surfaces of the ring-like oscillator and the electrodes.