Shear Force Sensor Sheet With Force Concentrators for X-Y Detection
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Solution Overview
Problem
Existing shear force sensor sheets fail to accurately measure shear forces in X- and Y-directions due to low detection sensitivity and design limitations, particularly when using materials with specific Poisson's ratios.
Innovation Solution
A shear force sensor sheet design incorporating a support substrate, lower detection electrodes, an elastic member, upper detection electrodes, an insulating layer, and a force concentrator with protrusions that enhance detection sensitivity by concentrating pressing forces on the upper detection electrodes, allowing for the measurement of shear forces in multiple directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If foam material with small Poisson's ratio is used as the elastic member, then the sensor sheet can measure pressing force in Z-direction, but the detection sensitivity is low due to the material not having high dielectric constant
Solution Approach 1:
The patent introduces an insulating layer as an intermediary between the upper and lower electrodes. This insulating layer has a high dielectric constant that compensates for the low dielectric constant of the foam elastic member, thereby achieving high detection sensitivity without being constrained by the Poisson's ratio of the elastic member material.
2Measurement precision
If adhesive layer with high Poisson's ratio is used to increase dielectric constant, then the dielectric constant increases, but the adhesive layer does not deform downward easily when pressed reducing detection sensitivity
Solution Approach 1:
The patent applies local quality by using different materials with different properties in different locations. The insulating layer is specifically positioned between the electrodes where high dielectric constant is needed for capacitance detection, while the foam elastic member provides the necessary deformation capability in the Z-direction. Each layer performs its specific function without compromising the other.
3Device complexity
If pressure sensor sheet measures only Z-direction component, then the structure is simple, but shear forces in X- and Y-directions cannot be measured
Solution Approach 1:
The patent achieves multi-functionality by enabling the sensor sheet to measure not only the pressing force in the Z-direction through elastic member deformation, but also the shear forces in the X- and Y-directions through the relative displacement of the upper and lower electrodes. The same basic structure serves multiple measurement purposes.
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 sensor sheet achieves high detection sensitivity independently of the Poisson's ratio of the elastic member, enabling accurate measurement of shear forces in X- and Y-directions, improving the detection capabilities of contact states in devices like tires and shoe soles.
Implementation Method 1
the elastic member with Poisson's ratio of 0 to 0.48 on the first electrodes
Implementation Method 2
can calculate a shear force applied on the protective layer based on a change in capacitance
Implementation Method 3
The force concentrator includes at least protrusions corresponding to the upper detection electrodes
Data Source
AI summary
A shear force sensor sheet has sufficiently high detection sensitivity independently of the Poisson's ratio of an elastic member. A shear force sensor sheet (1) includes lower detection electrodes (3), an elastic member (4), upper detection electrodes (5), an insulating layer (6), and a force concentrator (9) sequentially stacked on one another on a support substrate (2). The elastic member (4) and the insulating layer (6) are on a full surface of the support substrate (2). The lower detection electrodes (3) and the upper detection electrodes (5) are multiple strip electrodes located in a pressure-sensitive area (A1) on the elastic member, and are slidable to have a variable overlapping area between the upper strip electrodes and the lower strip electrodes. The force concentrator (9) includes at least protrusions (9a) corresponding to the upper detection electrodes (5).