Ultra-Sensitive Strain Sensor Using High Density Self-Aligned Nano-Cracks

This paper reports an ultra-sensitive strain sensor that uses perfectly aligned high density self-aligned nanoscale cracks. The common crack-based strain sensor is highly sensitive to strains thanks to its nano-size crack spacing. However, it has been difficult to make high density aligned cracks uniformly and reproducibly, and crack materials have been limited. In this paper, a strain sensor with perfectly aligned high density cracks made of various materials is fabricated using the atomic shadowing effect of general physical vapor deposition on a polymer nanograting substrate on which aligned cracks are automatically formed. As a result, we fabricate highly uniform nanoscale (sub-10 nm) aligned cracks made of various materials. The measured gauge factor of the fabricated sensor is 670 at a 0.3% strain, and this level of the gauge factor at the low strain has not been demonstrated before in crack-based sensors.