Piezoresistive Pressure Sensor Diaphragm Layout for Zero-Offset Sensing
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Solution Overview
Problem
Conventional pressure sensors face challenges in fabricating very thin diaphragms and often have large initial voltage offsets even when no pressure is applied.
Innovation Solution
The development of piezoresistive pressure sensors with diaphragms of varying thicknesses and irregular shapes, utilizing a Wheatstone bridge configuration with piezo-resistors at protruding corners, to achieve zero effective stress and sensitive pressure detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If very thin diaphragms are used to improve pressure sensitivity, then measurement precision is improved, but manufacturing precision becomes more difficult
Solution Approach 1:
The patent applies parameter changes by varying the thickness of different diaphragm regions rather than using a uniform thickness. The first diaphragm region has a first thickness while the second diaphragm region has a second thickness greater than the first, allowing the thin first region to provide high pressure sensitivity while the thicker second region ensures manufacturability and structural integrity.
Solution Approach 2:
The patent implements local quality by creating non-uniform diaphragm thickness distribution where different regions have different thicknesses optimized for their specific functions. The first diaphragm region is made thinner locally to enhance pressure sensitivity in the measurement area, while the second diaphragm region maintains greater thickness for structural support, resolving the contradiction between sensitivity and manufacturability.
2Ease of manufacture
If conventional diaphragm designs are used, then manufacturing is simpler, but initial voltage offsets are large
Solution Approach 1:
The patent employs asymmetry by using irregular shapes for the diaphragm regions instead of conventional symmetric designs. The first diaphragm region has an irregular shape with two opposite substantially rounded corners and two opposite irregular corners, while the second diaphragm region has a different irregular shape. This asymmetric configuration optimizes stress distribution to minimize initial voltage offsets while remaining manufacturable.
Solution Approach 2:
The patent changes geometric parameters by implementing irregular shapes with specific corner configurations rather than conventional regular shapes. The rounded corners and irregular corners create optimized stress patterns that reduce initial voltage offsets, demonstrating how parameter changes in geometry can improve measurement precision without significantly complicating manufacturing.
3Measurement precision
If irregular shaped diaphragms with protruding corners are used, then pressure sensitivity is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the diaphragm structure into distinct first and second diaphragm regions with different thicknesses and irregular shapes. Each region is optimized independently - the first region with protruding corners for maximum pressure sensitivity and the second region for structural support - allowing complex functionality to be achieved through modular design that manages overall device complexity.
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 sensors provide ultra-sensitive pressure measurement with negligible initial voltage offset and improved sensitivity to pressure changes, suitable for medical applications.
Implementation Method 1
the two opposite irregular corners comprise protruding pointed regions that comprise piezo-resistors that define a Wheatstone bridge
Implementation Method 2
the displacement defines the Wheatstone bridge, which is configured to output a voltage proportional to the displacement of the piezo-resistors
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A device comprising a piezoresistive pressure sensor is provided. The pressure sensor may comprise at least one diaphragm of a first thickness, surrounded by at least one second diaphragm of a second thickness, the second thickness being greater than the first thickness. The at least one diaphragm may be comprised of at least one irregular shape, wherein the at least one irregular shape includes two opposite substantially rounded corners and two opposite irregular corners. The irregular corners may comprise protruding pointed which comprise piezo-resistors. Opposite pairs of piezo-resistors may define a Wheatstone bridge.