Strain Sensor With Corrugated Elastic Layer
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Solution Overview
Problem
Conventional strain sensors using metal thin films have limited sensitivity and a small detection range, making them unsuitable for measuring large strain ranges in human joints, such as elbows and knees, where strains can exceed 50%.
Innovation Solution
A strain sensor with an elastic body featuring uneven surfaces and a conductive layer, where the unevenness on one surface allows for increased sensitivity by measuring changes in resistance or capacitance, using materials like PDMS, epoxy, and conductive materials like silver nanowires, to detect strain over a wider range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a metal thin film strain sensor is used, then the sensor structure is simple and manufacturing is easy, but the sensitivity is low and the detection range is limited to 3% or less
Solution Approach 1:
The elastic layer is designed with localized unevenness (protrusions and recesses) rather than uniform structure. This creates regions of different strain concentration, where the recess portions experience higher strain for the same applied deformation, thereby enhancing sensitivity without requiring complex overall sensor architecture
Solution Approach 2:
The invention transitions from a flat two-dimensional conductive layer to a three-dimensional structured elastic layer with protrusions and recesses. This dimensional change allows the conductive layer to follow the uneven surface, creating longer effective measurement paths and higher strain concentration in recess areas, thus improving sensitivity
2Adaptability or versatility
If a metal thin film strain sensor is used, then the manufacturing process is conventional and easy, but the strain detection range is limited to about 3% which is insufficient for human joint measurement
Solution Approach 1:
The elastic layer's physical parameters are modified by creating unevenness with specific protrusion heights (5-50 μm) and recess depths (5-50 μm). This parameter change allows the sensor to accommodate larger strain ranges (up to 50%) while maintaining manufacturability through standard fabrication processes
Solution Approach 2:
The sensor employs a composite structure combining an elastic layer (e.g., PDMS) with embedded conductive materials (silver nanowires, carbon nanotubes, or conductive polymers). This composite approach enables large strain accommodation through the elastic layer while maintaining electrical conductivity through the conductive material network
3Measurement precision
If the sensitivity of the strain sensor is increased, then small strain changes can be detected, but the measurement error according to strain occurrence speed increases
Solution Approach 1:
The conductive layer is designed to maintain continuous electrical contact throughout the elastic layer's deformation cycle. The interconnected conductive material network ensures continuous signal transmission during dynamic strain events, reducing measurement errors associated with intermittent or discontinuous sensing
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 improved sensitivity and a larger measurable strain range, allowing for effective monitoring of bio-signals and human motion, with adjustable sensitivity through varying the depth and width of the surface unevenness.
Implementation Method 1
detect a strain degree of a measurement target by sensing change in resistance or capacitance based on strain
Implementation Method 2
detect a strain degree of a measurement target by sensing change in resistance or capacitance based on strain
Implementation Method 3
an elastic layer which is provided with unevenness on one surface thereof
Data Source
AI summary
A deformation sensing sensor as disclosed includes a conductive material inside the body thereof such that, by sensing a change in resistance or capacitance resulting from a deformation, a degree of deformation of the measurement object can be detected. The body includes an elastic layer, which has a corrugation formed on one surface thereof, and a conductive layer, which is formed on the other surface of the elastic layer using a conductive material. When the body is deformed in the lateral direction of the surface on which the corrugation is formed, the change in resistance of the conductive layer before and after the deformation, or the change in capacitance thereof is measured, thereby detecting the degree of deformation of the measurement object.