Multi-Layer Force Sensor Stack with Pressure Concentrator
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Solution Overview
Problem
Traditional force sensors have limited dynamic range, leading to sensor saturation and inaccurate force measurement above a certain threshold, and are often difficult to calibrate, especially in multi-sensing element configurations.
Innovation Solution
The use of force sensor stacks comprising multiple layers responsive to different ranges of applied forces, combined with a pressure concentrator layer that directs forces to individual sensing elements, allowing for accurate measurement of forces from 0.01 PSI to 2500 PSI and simplifying calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional single-layer force sensors are used, then the device structure is simple, but the dynamic range is limited and sensor saturation occurs above a certain force threshold
Solution Approach 1:
The force sensor is divided into multiple sensing layers, each layer responsible for detecting force within a specific range. The first sensing layer detects forces from 0.01 PSI to 100 PSI, the second layer detects 100 PSI to 1000 PSI, and the third layer detects 1000 PSI to 2500 PSI. This segmentation allows each layer to operate within its optimal range, preventing saturation and enabling accurate measurement across the entire wide range.
Solution Approach 2:
The patent transitions from a single-layer two-dimensional sensing structure to a multi-layer three-dimensional stacked structure. By adding the vertical dimension with multiple sensing layers at different depths, the system achieves extended dynamic range while maintaining the ability to measure both light and heavy forces accurately.
2Measurement precision
If multiple sensing elements are used to expand measurement range, then the force measurement range increases, but calibration difficulty increases significantly
Solution Approach 1:
The system performs self-calibration by automatically selecting the appropriate sensing layer based on the magnitude of the applied force. When force is applied, the system detects which layer(s) are activated and uses only those layers for measurement, eliminating the need for manual calibration across all elements. The microcontroller automatically adjusts the measurement process based on the active sensing elements.
Solution Approach 2:
The calibration process is made dynamic and adaptive rather than static. The system continuously determines which sensing elements are active based on the current force magnitude and adjusts the measurement accordingly. This dynamic approach simplifies calibration because the system adapts to different force ranges automatically rather than requiring fixed calibration for all elements.
3Measurement precision
If force is distributed across multiple sensing elements, then the measurement coverage increases, but determining individual element forces becomes complex
Solution Approach 1:
The patent introduces a pressure concentrator layer as an intermediary between the applied force and the multiple sensing elements. This layer contains pressure concentrator features that channel and focus the distributed force onto specific sensing elements, making it easier to determine which elements are active and what forces they are experiencing. The pressure concentrator layer translates distributed pressure into concentrated force signals at specific sensing locations.
Data Source
AI summary
Described is a force sensor stack configured to measure incident force. Data from the force sensor stack may be used to determine a weight of an object, determine a force distribution of the object resting on the force sensor stack, and so forth. The force sensor stack may comprise a plurality of force sensor layers. Each of the force sensor layers may be responsive to a different range of applied forces. The combined force sensor stacks may thus provide a wide dynamic range. A pressure concentrator layer may be configured to direct the incident force to particular portions of the force sensor layers.