Three-Axis Piezoelectric Accelerometer with Orthogonal Arms
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Solution Overview
Problem
Conventional shock sensors are limited to single-axis acceleration detection, lacking the capability to measure acceleration in multiple axes, which restricts their application in detecting complex shock patterns.
Innovation Solution
A three-axis piezoelectric sensor integrated with semiconductor die and MEMS technology, featuring a flexible plate with orthogonal arms and piezoelectric capacitors, allows for the detection of acceleration in multiple axes by converting strain into electrical signals through a poling process that aligns the piezoelectric domains for enhanced signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If single-axis accelerometers are used, then device complexity is reduced, but measurement precision is limited to one axis only
Solution Approach 1:
The flexible plate is segmented into four arms extending in orthogonal directions, with piezoelectric capacitors placed on each arm. This segmentation enables independent strain measurement along multiple axes while maintaining a unified sensor structure, resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The sensor transitions from single-axis to three-axis acceleration detection by adding orthogonal arms in different spatial dimensions. The four arms are arranged to detect strain along X, Y, and Z axes, enabling comprehensive 3D shock pattern detection without proportionally increasing device complexity
2Measurement precision
If piezoelectric capacitors are placed on all four arms, then measurement precision is improved, but manufacturing precision requirements increase
Solution Approach 1:
All four piezoelectric capacitors use the same structure, material properties, and poling process, making them universally interchangeable. This universality simplifies manufacturing by reducing the variety of precision requirements, while still achieving high measurement precision through the combined output of all four capacitors
Solution Approach 2:
The poling process applies electric fields along specific crystallographic directions to align piezoelectric domains. By carefully controlling the poling field parameters (direction, magnitude, duration), the sensor achieves enhanced signal-to-noise ratio while maintaining feasible manufacturing precision through standardized processing parameters
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 the detection of three-axis acceleration changes, providing a more comprehensive understanding of shock patterns and improving the sensitivity and accuracy of shock sensing applications.
Implementation Method 1
The piezoelectric sensor can be integrated on to a semiconductor die with the circuitry that drives the sensor and processes its output signals... piezoelectric capacitors are on each of the arms... converting strain into electrical signals through a poling process that aligns the piezoelectric domains
Data Source
AI summary
An acceleration change sensor includes a flexible member comprising extensions extending from a central portion. Piezoelectric capacitors are provided on respective extensions. A proof mass is coupled to the flexible member and offset from each extension of the plurality of extensions.