Vertical Graphene Strain Sensor with Reticular Cracks
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Solution Overview
Problem
Traditional strain sensors based on non-flexible materials are limited in application due to low sensitivity and inability to recognize sound timbre, while stretchable sensors face challenges with low stretch ratios and sensitivity factors, making them unsuitable for detecting vibrations and sounds effectively.
Innovation Solution
A stretchable strain sensor utilizing vertical graphene with high-density reticular cracks and a thickness of 100 nanometers to 100 microns, capable of recognizing timbre frequencies up to 2500 Hz and achieving sensitivity factors greater than 200 at 50% stretch, utilizing an ultrasonic dissociation method to enhance crack density and maintain electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a metal film is plated on a stretchable elastic substrate to create a stretchable strain sensor, then the sensor can be stretched and sense sound intensity, but the metal film easily breaks during stretching causing sensor failure and the maximum stretching amount is limited to only 2%
Solution Approach 1:
The patent employs vertical graphene with a porous structure containing high-density reticular cracks. This porous architecture allows the material to accommodate stretching deformation through crack opening and closing mechanisms, enabling stretch ratios exceeding 50% while maintaining structural integrity and electrical connectivity, thus resolving the contradiction between stretchability and reliability
Solution Approach 2:
The patent creates a composite structure by combining vertical graphene with stretchable elastic substrate materials. The vertical graphene layer provides mechanical strength and electrical conductivity, while the elastic substrate provides stretchability. This composite approach enables the sensor to achieve both high stretch ratio (>50%) and high sensitivity factor (>200) simultaneously
2Adaptability or versatility
If elastic material with low Young's modulus is used to create stretchable strain sensors, then the sensor can be stretched, but the natural frequency is low and cannot follow the vibration frequency of sound wave, limiting audio recognition capability
Solution Approach 1:
The patent changes the material parameters by using vertical graphene with specific thickness (100 nanometers to 100 microns) and controlled crack density. This parameter optimization allows the sensor to achieve both high stretchability and high natural frequency, enabling recognition of sound timbres with frequencies up to 2500 Hz while maintaining stretch ratios over 50%
3Adaptability or versatility
If vertical graphene with low-density cracks is used in stretchable strain sensors, then the sensor can be stretched, but the sensitivity factor is limited with maximum GF of 88.4 and cannot distinguish sound timbres
Solution Approach 1:
The patent utilizes vertical graphene with high-density reticular cracks forming a porous structure. This high crack density creates sufficient piezoresistive effect during stretching, achieving sensitivity factor greater than 200, while the porous structure maintains stretchability over 50%. The high-density crack network enables detection of subtle vibrations for sound timbre recognition up to 2500 Hz
Solution Approach 2:
The patent optimizes the crack density parameter and vertical graphene thickness (100 nanometers to 100 microns) to achieve the desired balance between stretchability and sensitivity. By controlling these parameters, the sensor achieves sensitivity factor >200 and stretch ratio >50%, enabling both stretchability and sound timbre recognition capabilities
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 a high stretch ratio of over 50%, enabling effective recognition of sound timbre and vibrations, with enhanced sensitivity and natural frequency, allowing for applications such as fetal monitoring and artificial eardrum functionality.
Implementation Method 1
the sensitivity factor (defined as the variation of the relative resistance divided by the relative deformation quantity, abbreviated as GF)
Implementation Method 2
utilizing an ultrasonic dissociation method to enhance crack density and maintain electrical connectivity
Data Source
AI summary
A stretchable strain sensor based on vertical graphene having a stretch ratio of more than 50% and is capable of recognizing timbre with frequency greater than f hertz, f being 100, 800 or 2500, and having a sensitivity factor greater than 100 at 50% stretch, wherein the vertical graphene comprises a bottom plane layer and a vertical layer and contains high-density reticular cracks, wherein the directions of the cracks can be transverse, vertical and oblique directions, wherein the reticular cracks divide the vertical graphene into a plurality of small blocks, and adjacent small blocks are electrically connected through the vertical layer in stretched state, the cracks widen, but still can be bridged by the vertical layer, the two sides of the cracks still remain electrically connected, the sensor remains effective, wherein average diameter range of the plane of each small block is between 5 and 20 microns.