Highly sensitive strain sensors with ultra-low detection limit based on pre-defined serpentine cracks

Area of Science:

• Materials Science
• Electrical Engineering
• Biomedical Engineering

Background:

• Flexible and stretchable strain sensors are crucial for human health monitoring and human-machine interfaces.
• Microcrack-based strain sensors offer high sensitivity and wide sensing ranges but suffer from performance drift due to uncontrolled crack formation.

Purpose of the Study:

• To introduce a novel resistive strain sensor with pre-defined cracks for enhanced sensitivity, linearity, and reliability.
• To overcome the limitations of uncontrolled microcrack formation in existing strain sensors.

Main Methods:

• Fabrication of a novel resistive strain sensor by pre-defining cracks within conductive serpentine curves encapsulated by pre-stretched thin films.
• Modulation of ohmic contact through intricately designed conductive serpentine curves.
• Testing sensor performance under various deformations, including off-axis bending and twisting.

Main Results:

• Achieved a high gauge factor of 495 and exceptional linearity (R^2 > 0.98).
• Demonstrated an ultra-low detection threshold of 0.01% strain.
• Maintained performance integrity during off-axis deformations and showed potential in a driver fatigue detection system using machine learning.

Conclusions:

• The novel pre-defined crack strain sensor offers superior sensitivity, linearity, and robustness compared to previous designs.
• The sensor technology shows significant promise for applications in healthcare monitoring, wearable biomechanical systems, and human-machine interfaces.
• Successful demonstration of driver fatigue detection highlights the practical utility of this advanced sensor technology.