Single‐Crack‐Activated Ultrasensitive Impedance Strain Sensor

Abstract A development of single‐crack‐activated impedance strain sensors with unprecedented sensitivity is demonstrated first. The gauge factor of the device is beyond 10 8 in 10 −4 strain range in comparison with the reported highest gauge factor 1.5 × 10 5 within 6e‐1 strain range, and the displacement sensitivity is 1.6 MΩ nm −1 . The extremely high sensitivity is attributed to the transition region which has never been studied before. Multiple‐crack‐based sensors, however, cannot work in the transition region due to complicated interaction among cracks, which essentially limits their sensitivity. Additionally, studying a precisely controllable single crack rather than multiple cracks is favorable for excluding other factors such as crack spacing, difference among cracks, and interaction among cracks, simplifying the model and facilitating better understanding of the underlying mechanism of the device. The device can satisfy requirements of mechanical flexibility, durability, and repeatability. In addition, the device developed is capable of measuring displacement in nanometers range or force in tens of nanonewton range, and has the potential to be applied in various fields, such as specific biomolecular recognition.