Flexible Force Sensor With Magnetic Cilia for Dual-Range Detection
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Solution Overview
Problem
Existing flexible tactile sensors face a trade-off between sensitivity to small forces and the range of measurable forces, with softer materials increasing sensitivity but reducing the maximum measurable force.
Innovation Solution
A flexible tactile sensor design combining a flexible body with embedded magnets and soft magnetized cilia, which uses magnetic sensing elements to detect both small and large forces by deforming the cilia and main body, respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If softer materials are used to increase sensitivity to small forces, then sensitivity is improved, but the maximum measurable force is reduced
Solution Approach 1:
The sensor is divided into two functional segments: flexible projections for detecting small forces and the main flexible body for detecting large forces. This segmentation allows each part to be optimized for its specific force range, resolving the contradiction between sensitivity and maximum measurable force.
Solution Approach 2:
Different parts of the sensor have different mechanical properties tailored to their function: the flexible projections are designed with specific stiffness for small force detection, while the main body provides the structural foundation for large force measurement. This local differentiation enables the sensor to handle both small and large forces effectively.
2Adaptability or versatility
If a flexible sensor structure is used to improve safety and robustness, then flexibility is improved, but sensitivity to small forces is limited by the stiffness of the sensor body
Solution Approach 1:
The sensor separates the flexibility function (main body) from the sensitivity function (flexible projections). The projections act as force amplifiers that concentrate small forces onto the sensing elements, while the main body provides overall flexibility without compromising small force 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 to sub-mN forces and a wide range of measurable forces, suitable for various applications including robotics and prosthetics, with a simple and efficient manufacturing process.
Implementation Method 1
A Hall-effect based compact sensor that can measure three-axial forces is described in Non-patent Document 3. The referenced sensor consists of a soft silicon body, a magnet embedded in this body, and a Hall-effect sensor.
Implementation Method 2
a magnet connected to the flexible body; and a plurality of flexible projections having magnetic material embedded therein attached to the flexible body
Data Source
AI summary
A tactile sensor, consisting of a flexible main body with embedded magnets, soft magnetized cilia on the main body, and magnetic sensing elements embedded on the substrate layer. The magnetic sensing elements produce signals in response to the changes in the magnetic field. Tactile interaction with the main body and cilia displaces the magnetic material and changes the magnetic field. Cilia are sensitive to sub-mN force magnitudes, the main body is sensitive to larger range of force magnitudes. Multiple sensing elements, magnets and cilia may be distributed over large and curved surfaces. Three-axial forces can be measured using the sensor.