Semiconductor Cantilever Pressure Sensor for Low-Frequency Detection
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Solution Overview
Problem
Existing pressure sensors face limitations in detecting minute pressure fluctuations due to the thickness and deformation constraints of piezoelectric elements, making it difficult to set a lower limit frequency and achieve high precision in pressure fluctuation detection.
Innovation Solution
A pressure sensor with a semiconductor cantilever and displacement measurement unit, where the cantilever is flexurally deformed based on pressure differences, allowing for precise detection of pressure fluctuations by adjusting the gap width and cavity volume to set a desired lower limit frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a piezoelectric element is used for pressure detection, then the sensor can detect pressure fluctuation, but the thickness reduction is limited and large deformation is difficult to achieve
Solution Approach 1:
The patent changes the material parameter from piezoelectric material to semiconductor material, enabling thickness reduction from typical piezoelectric element thickness (rarely reduced) to tens or hundreds of nanometers. This parameter change allows the cantilever to achieve large flexural deformation while maintaining structural integrity, directly resolving the contradiction between thickness reduction and deformation capability.
2Measurement precision
If the piezoelectric element thickness is reduced to increase deformation, then detection sensitivity improves, but the element structure becomes difficult to maintain
Solution Approach 1:
The patent changes the material parameter from piezoelectric material to semiconductor material, enabling thickness reduction from typical piezoelectric element thickness (rarely reduced) to tens or hundreds of nanometers. This parameter change allows the cantilever to achieve large flexural deformation while maintaining structural integrity, directly resolving the contradiction between thickness reduction and deformation capability.
3Measurement precision
If multiple piezoelectric sensors with various design parameters are produced to determine lower limit frequency, then the detectable frequency band can be characterized, but the process becomes practically difficult and complex
Solution Approach 1:
The patent changes the material parameter from piezoelectric material to semiconductor material, enabling thickness reduction from typical piezoelectric element thickness (rarely reduced) to tens or hundreds of nanometers. This parameter change allows the cantilever to achieve large flexural deformation while maintaining structural integrity, directly resolving the contradiction between thickness reduction and deformation capability.
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
Enables high-precision detection of minute pressure fluctuations and arbitrary setting of the detectable frequency band, overcoming the limitations of piezoelectric sensors by reducing thickness and improving sensitivity.
Implementation Method 1
the cantilever being flexurally deformed according to a pressure difference between an inside and an outside of the cavity
Implementation Method 2
a displacement measurement unit which measures a displacement of the cantilever vibrating according to the pressure difference
Data Source
Figure 1~2
Figure 3A~3B
Figure 4A~4C
AI summary
A pressure sensor includes a sensor body which has a first surface and a cavity with an opening in the first surface, a cantilever which has a base end portion supported on the first surface and a distal end portion provided to form a gap from a peripheral edge of the opening inside the opening, is flexurally deformed according to a pressure difference between an inside and an outside of the cavity, and is formed of a semiconductor material, and a displacement measurement unit which measures a displacement of the cantilever vibrating according to the pressure difference at a frequency larger than a lower limit frequency fLOW (Hz) defined by Expression (1), where a width (µm) of the gap is represented by G, a volume (ml) of the cavity is represented by V, and a proportional constant is represented by k. fLOW=k⋅G2/V