Piezoresistor Placement Using Stress Intersection Plots
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Solution Overview
Problem
Existing electronic device designs, such as piezoresistive force sensors, face challenges in optimizing the placement of piezoresistors to simultaneously meet both force-induced and temperature-induced mechanical stress requirements, leading to non-uniform electrical outputs due to inseparable stress responses.
Innovation Solution
A method involving generating conditional plots for force-induced and temperature-induced stress levels, followed by an intersection plot to identify optimal regions where both criteria are met, allowing for precise piezoresistor placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If piezoresistors are placed in locations with large mechanical stress to achieve good force response, then force-induced electrical output is improved, but temperature-induced mechanical stress also increases causing undesired output
Solution Approach 1:
The patent segments the sensor surface into multiple discrete locations with different stress characteristics. By evaluating and selecting specific locations (such as corners or edges) where the stress distribution has particular properties, the method enables separate optimization for force response and temperature compensation without requiring a single uniform placement strategy for all piezoresistors
Solution Approach 2:
The patent applies local quality by assigning different placement criteria to different regions of the sensor. Certain locations are identified as having favorable force response characteristics while others provide better temperature stability. The method allows selecting specific local regions (e.g., placing piezoresistors at corners rather than center) to achieve optimal performance for each criterion simultaneously
2Object-generated harmful factors
If piezoresistors are placed in locations with small temperature-induced mechanical stress to minimize temperature impact, then temperature-induced electrical output is reduced, but force-induced mechanical stress also decreases reducing force response
Solution Approach 1:
The patent segments the sensor surface into multiple discrete locations with different stress characteristics. By evaluating and selecting specific locations (such as corners or edges) where the stress distribution has particular properties, the method enables separate optimization for force response and temperature compensation without requiring a single uniform placement strategy for all piezoresistors
Solution Approach 2:
The patent applies local quality by assigning different placement criteria to different regions of the sensor. Certain locations are identified as having favorable force response characteristics while others provide better temperature stability. The method allows selecting specific local regions (e.g., placing piezoresistors at corners rather than center) to achieve optimal performance for each criterion simultaneously
3Device complexity
If a single piezoresistor placement location is used for both force and temperature criteria, then device complexity is reduced, but it becomes impossible to simultaneously meet both performance requirements
Solution Approach 1:
The patent segments the sensor surface into multiple discrete locations with different stress characteristics. By evaluating and selecting specific locations (such as corners or edges) where the stress distribution has particular properties, the method enables separate optimization for force response and temperature compensation without requiring a single uniform placement strategy for all piezoresistors
Solution Approach 2:
The patent applies local quality by assigning different placement criteria to different regions of the sensor. Certain locations are identified as having favorable force response characteristics while others provide better temperature stability. The method allows selecting specific local regions (e.g., placing piezoresistors at corners rather than center) to achieve optimal performance for each criterion simultaneously
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
This method enables direct and visual determination of optimal piezoresistor locations, ensuring maximum force-induced output and minimal temperature-induced output, enhancing sensor performance.
Implementation Method 1
a piezoresistive force sensor is based on piezoresistors, which convert mechanical stress resulting from a force applied to the sensor into electrical outputs
Implementation Method 2
due to differences in thermal coefficient of expansion (TCE) among various materials from which the piezoresistive force sensor is made, and due to differences in TCE between the piezoresistive force sensor and a substrate
Data Source
AI summary
The present disclosure relates to a method of determining an optimal solution for an electronic device with response to two or more orthogonal input loads. The disclosed method starts with generating first and second conditional plots of the electronic device based on first and second criteria, respectively. Herein, a first characteristic within the first conditional plot meets the first criterion when a first load is applied to the electronic device, while a second characteristic within the second conditional plot meets the second criterion when a second load is applied to the electronic device. Generating the first and second conditional plots are independent from each other, and the second criterion is different from the first criterion. An intersection plot is then generated by overlaying the first and second conditional plots. The intersection plot indicates whether the electronic device has one or more solution locations satisfying both the first and second criteria.