Anisotropic Substrate for Vertical Pressure Sensing
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Solution Overview
Problem
Crack-based sensors are limited in detecting mechanical signals due to their planar design, which only allows for in-plane deformation detection, making them insensitive to vertically applied stresses and lacking directional flexibility in signal detection.
Innovation Solution
An anisotropic Poisson's ratio substrate with linear concave and convex patterns in two stacked layers, where the elastic modulus of each layer differs, enhancing lateral deformation and enabling detection of pressure applied perpendicular to the substrate's surface by increasing the Poisson's ratio in the x-direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a planar crack-based sensor design is used, then the sensor structure is simple and easy to manufacture, but the sensor can only detect in-plane deformation and cannot detect vertically applied stresses
Solution Approach 1:
The patent transitions from a two-dimensional planar sensor design to a three-dimensional structure by stacking multiple sensor layers at different orientations. This dimensional change enables the sensor to detect stresses from multiple directions including vertical pressures, overcoming the limitation of planar designs while maintaining manufacturing simplicity through standardized layer stacking
2Adaptability or versatility
If trench or pop-up geometries are added to reduce directional constraints, then the sensor can detect signals from multiple directions, but the fabrication becomes inefficient and difficult
Solution Approach 1:
The patent divides the sensor into multiple independent planar layers, each capable of detecting stresses in specific directions. By segmenting the sensor into stackable layers with different orientations, it achieves multi-directional detection capability while avoiding the complex fabrication processes required for trench or pop-up geometries, as each layer can be manufactured using standard planar techniques
Solution Approach 2:
Instead of adding complex three-dimensional geometries like trenches or pop-ups to a single layer, the patent uses the stacking dimension to achieve multi-directional detection. Multiple two-dimensional layers are stacked to create three-dimensional detection capability, simplifying fabrication compared to modifying individual layers with complex geometries
3Measurement precision
If the Poisson's ratio anisotropy is increased six-fold, then the sensitivity and detection range of the sensor are improved, but the substrate structure becomes more complex
Solution Approach 1:
The patent introduces asymmetric structural features in the substrate, such as varying the orientation angles of different layers or using layers with different mechanical properties. This asymmetric design creates Poisson's ratio anisotropy, enhancing sensitivity to specific stress directions while maintaining a relatively simple overall substrate structure through controlled asymmetry rather than complex symmetric patterns
4Device complexity
If the sensor is designed to detect only in-plane deformation, then the sensor structure remains simple, but the sensor lacks durability and stability under vertical pressures up to 10 MPa
Solution Approach 1:
The patent adds the stacking dimension to the sensor design, creating a multi-layer structure that can withstand and detect vertical pressures. This three-dimensional configuration distributes mechanical stresses across multiple layers, improving durability and stability under vertical pressures up to 10 MPa while maintaining the simplicity of individual planar layers
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 anisotropic substrate significantly enhances the sensitivity and durability of crack-based pressure sensors, allowing for efficient detection of fine vertical stresses and maintaining linearity and stability up to 10 MPa, with a six-fold difference in Poisson's ratio anisotropy, resulting in improved sensitivity and a wider detection range.
Implementation Method 1
anisotropic Poisson's ratio substrate (APS)... increasing the Poisson's ratio in the x-direction... six-fold difference in Poisson's ratio anisotropy
Implementation Method 2
crack-based sensor... excellent sensitivity... capable of detecting a minute mechanical signal (2% deformation) with a gauge factor equal to or larger than 16,000
Data Source
AI summary
Disclosed are an anisotropic mechanical expansion (anisotropic Poisson's ratio) substrate and a crack-based pressure sensor using the same. The substrate having an anisotropic Poisson's ratio includes a first layer having linear concave and convex patterns arranged in parallel to each other on a surface thereof; and a second layer having linear convex and concave patterns respectively engaged with the linear concave and convex patterns of the first layer on a surface thereof, wherein the first layer and the second layer are stacked with each other so that the linear convex and concave patterns of the second layer are respectively engaged with the linear concave and convex patterns of the first layer, wherein an elastic modulus of the first layer is different from an elastic modulus of the second layer.