Bending Sensor With Dual Resistance Layers And Pre-Formed Cracks
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Solution Overview
Problem
Existing bending sensors have low sensitivity and varying sensitivity among multiple strips, making it difficult to accurately detect deformation and distinguish between ON and OFF states due to reliance on crack distribution and shape in the resistance layer.
Innovation Solution
A bending sensor design featuring a high resistance layer, a low resistance layer with cracks that open during deformation, and an insulating layer, connected in parallel with electrode portions, where the electrical resistance varies mainly based on crack opening, providing high sensitivity and consistent resistance outputs for easy state determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cracks are scattered in the resistance layer to increase sensitivity, then the sensitivity increases, but the sensitivity varies among multiple strips due to distribution and shape variations of cracks
Solution Approach 1:
Cracks are pre-formed in the low resistance layer before the sensor is assembled. This preliminary action ensures that the cracks are consistently positioned and distributed across all strips, eliminating the variability that would occur if cracks formed randomly during operation. The pre-formed cracks provide uniform sensitivity characteristics across multiple sensors.
Solution Approach 2:
The invention changes the resistance parameter by creating a dual-layer structure with different resistance values. The low resistance layer with pre-formed cracks provides a baseline resistance that opens predictably under stress, while the high resistance layer provides a contrasting resistance path. This parameter differentiation enhances sensitivity while maintaining consistency across multiple strips.
2Device complexity
If a single resistance layer with cracks is used to detect bending, then the structure is simple, but it is difficult to distinguish between ON and OFF states due to varying resistance outputs
Solution Approach 1:
The resistance detection system is segmented into two distinct layers: a high resistance layer and a low resistance layer with cracks. Each layer contributes differently to the overall resistance output depending on the bending state. This segmentation allows the sensor to provide clearly differentiated resistance values for ON and OFF states, improving state distinguishability while maintaining relatively simple construction.
Solution Approach 2:
The invention uses a composite structure combining two different resistance layers. The high resistance layer and low resistance layer with cracks work together to produce distinct electrical characteristics in different states. This composite approach enhances the clarity of state differentiation without significantly increasing device complexity.
3Reliability
If metal fine particles are dispersed in silicone rubber to create a pressure conductive member, then the sensor becomes conductive under load, but the sensitivity is low due to gradual resistance reduction
Solution Approach 1:
The low resistance layer incorporates pre-formed cracks that create porous pathways for electrical conduction. When the sensor is not bent, the cracks are closed and provide conductive paths through the conductive filler. When bent, the cracks open and abruptly interrupt conduction. This porous crack structure provides higher sensitivity compared to the gradual resistance change in densely packed metal particle composites.
Solution Approach 2:
The invention replaces the gradual mechanical compression mechanism (metal particles being pushed together) with a fracture-based mechanism (cracks opening and closing). This substitution creates a more sensitive response where small deformations cause abrupt changes in electrical resistance, significantly improving measurement precision while maintaining reliable conductive state detection.
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 achieves high sensitivity and consistent resistance variations, allowing for accurate detection of deformation and easy differentiation between ON and OFF states, reducing the risk of misinterpretation and minimizing sensitivity variations among multiple sensors.
Implementation Method 1
a crack having an opening on the tensile surface and developing in a laminating direction, the low resistance layer having lower electrical resistance than the high resistance layer in a state where the crack is closed
Implementation Method 2
the variation in the electrical resistance relies on a distribution, degree of opening, and shape of the cracks
Implementation Method 3
a high resistance layer including a parent material composed of one of a resin and an elastomer and a conductive filler dispersed in the parent material
Implementation Method 4
the metal fine particles are dispersed in the silicone rubber. With a load exerted on the pressure sensor, the dispersed metal fine particles approach one another, thus reducing electrical resistance
Implementation Method 5
an insulating layer including at least the parent material from among the parent material composed of one of the resin and the elastomer, and an insulation filler dispersed in the parent material, the insulating layer being disposed between the high resistance layer and the low resistance layer and electrically insulating the high resistance layer from the low resistance layer
Implementation Method 6
a bending sensor that detects a bending deformation from a variation in electrical resistance
Data Source
AI summary
A bending sensor includes a high resistance layer; a low resistance layer having a crack and a lower electrical resistance than the high resistance layer in a state where the crack is closed; an insulating layer between the high and low resistance layers; and a plurality of electrode portions connecting electrically in parallel the high resistance and low resistance layers. In an OFF state where a bend amount is small, the crack is unlikely to open and a combined resistance of electrical resistances of the high resistance layer and the low resistance layer is output as OFF resistance from the plurality of electrode portions. In an ON state where the bend amount is large, the crack is likely to open and at least the electrical resistance of the high resistance layer is output as ON resistance higher than the OFF resistance from the plurality of electrode portions.