Piezoresistive Pressure Sensor Diaphragm for Low-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 without applied pressure.
Innovation Solution
The design includes a pressure sensor with a first diaphragm of a first thickness surrounded by a second diaphragm of a greater thickness, composed of multiple layers to achieve zero effective stress, featuring irregular shapes with protruding piezo-resistors forming a Wheatstone bridge, which outputs a voltage proportional to displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If very thin diaphragms are used to enhance sensitivity, then sensitivity to pressure changes is improved, but manufacturing difficulty increases
Solution Approach 1:
The diaphragm is segmented into a first diaphragm region with first thickness and a second diaphragm region with second thickness greater than the first thickness. This segmentation allows the central region to be ultra-thin for high sensitivity while the peripheral region is thicker for structural support and manufacturability, resolving the contradiction between sensitivity and ease of manufacture.
Solution Approach 2:
Different regions of the diaphragm are assigned different thicknesses: the first diaphragm region has a first thickness optimized for pressure sensitivity, while the second diaphragm region has a greater second thickness for mechanical strength. This local quality differentiation enables the thin diaphragm to be manufactured without compromising overall structural integrity.
2Measurement precision
If conventional diaphragm designs are used, then manufacturing is simpler, but initial voltage offsets are large
Solution Approach 1:
The diaphragm is divided into functionally distinct first and second diaphragm regions with different thicknesses. The first diaphragm region contains the piezoresistors and has minimal thickness for zero stress, while the second region provides support. This segmentation eliminates initial voltage offsets by ensuring piezoresistors experience zero stress at zero pressure, while maintaining manufacturability through the thicker peripheral region.
Solution Approach 2:
The thickness parameter of the diaphragm is varied across different regions: the first thickness in the first diaphragm region is optimized for zero stress and minimal voltage offset, while the second thickness in the second region provides mechanical support. This parameter change resolves the contradiction between measurement precision and 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 solution enables the fabrication of ultra-sensitive pressure sensors with negligible initial voltage offset and enhanced 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
Data Source
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.