Crack Sensor Polymer Healing Layer Suppressing Crack Growth
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Solution Overview
Problem
Flexible crack sensors used in biometric and electronic devices suffer from decreased sensitivity due to crack deepening and instability after repeated tests, leading to reduced performance.
Innovation Solution
A crack sensor with a healing polymer layer that suppresses crack growth and restores cracks using a restoring force generated via external energy, such as heat, light, or electric energy, maintaining sensitivity and durability even after repeated use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a crack sensor is used repeatedly to detect mechanical stimuli, then the sensor can accumulate detection data and improve monitoring capability, but the cracks deepen and sensitivity decreases
Solution Approach 1:
The polymer layer is pre-applied to the conductive layer before crack formation occurs. This preliminary protective action allows the polymer to suppress crack growth from the earliest stages, preventing sensitivity degradation before it happens. The polymer is positioned to cover the conductive layer in advance, creating a protective barrier that actively suppresses crack propagation as soon as stress is applied during sensor operation.
2Measurement precision
If the crack structure is used to achieve high sensitivity (close to 2000 in 2% strain range), then the sensor can detect minute stresses, but the stress accumulates and the crack deepens
Solution Approach 1:
The polymer layer applies a preliminary counteracting force to stress accumulation in the crack structure. By positioning the polymer between the substrate and conductive layer (or on the conductive layer), it creates an opposing mechanical response that prevents stress from concentrating and deepening the cracks. This anti-action maintains the crack structure's sensitivity while preventing its degradation.
Solution Approach 2:
The sensor combines the conductive layer (providing sensitivity through crack structure) with the polymer layer (providing stability and crack suppression). This composite structure allows the two materials to work together - the conductive layer maintains high measurement precision through its crack geometry, while the polymer layer ensures long-term stability by suppressing crack deepening.
3Reliability
If external energy is applied to increase the restoring force of the polymer layer, then cracks can be restored and sensitivity maintained, but energy consumption increases
Solution Approach 1:
The polymer layer's restoring force can be modulated by changing external parameters such as temperature, light exposure, or electric field application. By adjusting these parameters, the polymer's mechanical properties change dynamically - increasing restoring force when crack restoration is needed, and reducing it during normal operation to minimize energy consumption. This allows controlled energy usage only when sensitivity degradation is detected.
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 maintains high sensitivity and stability through crack healing, allowing for prolonged use without performance degradation, suitable for flexible electronic circuits and wearable devices.
Implementation Method 1
the restoring force is generated via a bond between oxygen and hydrogen contained in the polymer layer
Implementation Method 2
when at least one of heat, light, and electric energy is applied to the polymer layer, the restoring force of the polymer layer is increased
Data Source
AI summary
A crack sensor with crack healing is provided. The sensor having: a substrate; a conductive layer disposed on the substrate, wherein the conductive layer contains cracks formed therein; and a polymer layer disposed between the substrate and the conductive layer, or disposed on the conductive layer and not between the substrate and the conductive layer; wherein a restoring force of the polymer layer suppresses further growth of the cracks or restores cracks.