Redundant Piezoresistive Pressure Sensor Array on a Shared Diaphragm
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Solution Overview
Problem
Existing aircraft pressure sensors lack redundancy, leading to potential errors in air data measurement, and installing multiple pitot tubes to achieve redundancy is costly.
Innovation Solution
A micromechanical redundant piezoresistive array pressure sensor with multiple Wheatstone bridge circuits and serpentine resistors on a diaphragm, providing redundant pressure measurements through a health monitoring system that includes a prognostic processor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple pitot tubes are installed to achieve sensor redundancy, then measurement reliability is improved, but system cost increases
Solution Approach 1:
The patent combines multiple piezoresistive sensor elements onto a single diaphragm, creating an integrated redundant sensing system. Instead of using separate pitot tubes, multiple sensor elements (at least three) are fabricated on one shared diaphragm structure, merging the redundant sensing function into a single component that reduces system cost while maintaining reliability
Solution Approach 2:
The patent creates redundant copies of piezoresistive sensor elements on the same diaphragm. Multiple identical or similar sensor elements are fabricated in array configurations (such as Wheatstone bridge circuits), providing redundant measurement capabilities without requiring additional external structures
2Reliability
If multiple piezoresistive sensor elements are integrated on a single diaphragm, then measurement reliability is improved through redundancy, but manufacturing complexity increases
Solution Approach 1:
The patent segments the diaphragm into multiple distinct sensing zones, each containing piezoresistive elements that can be independently patterned and connected. This segmentation allows for modular fabrication where sensor elements are distributed across different regions of the diaphragm, enabling systematic manufacturing while maintaining redundancy
Solution Approach 2:
The patent employs micromachining and semiconductor fabrication techniques to precisely control the geometric parameters and material properties of piezoresistive elements. By controlling doping concentrations, resistor geometries, and diaphragm thickness, the patent achieves consistent sensor performance across multiple elements, simplifying the manufacturing of redundant sensor arrays
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
Reduces measurement errors and sensor costs by ensuring accurate and reliable air data measurements through redundant pressure sensing, allowing for early detection of sensor failures and reducing total sensor error to less than 0.02% of full scale.
Implementation Method 1
micromechanical piezoresistive sensor element
Data Source
Figure 1A~1B
Figure 2A~2D
Figure 3A~3D
AI summary
A micromechanical piezoresistive pressure sensor (40;340) includes a diaphragm (44) configured to mechanically deform in response to an applied load, a sensor substrate located on the diaphragm, and a number of piezoresistive resistance devices located on the sensor substrate. The piezoresistive resistance devices are arranged in a first planar array defining a grid pattern having two or more rows, each row being aligned in a first direction. The piezoresistive resistance devices are configured to be electrically connected in a number of bridge circuits (30), whereby the piezoresistive resistance devices in each row is electrically connected in an associated bridge circuit. A method of using the micromechanical piezoresistive pressure sensor is also disclosed.