Parallel Microcracks-based Ultrasensitive and Highly Stretchable Strain Sensors

TLDR

Demand for flexible, skin‑attachable, wearable strain sensors is rising, yet achieving both high sensitivity and high stretchability remains a major challenge. We aim to develop highly sensitive and stretchable strain sensors using reversible microcrack formation in composite thin films. The sensors are fabricated by generating controllable parallel microcracks in graphite thin films coated on elastomer substrates. Graphite films with short microcracks achieve gauge factors up to 522.6 and stretchability ≥50 %, while long‑crack films reach ultrahigh sensitivity (gauge factor 11,344) with limited stretchability ≤50 %, and the sensors perform well in physiological monitoring, motion capture, vibration detection, pressure sensing, and soft robotics.

Abstract

There is an increasing demand for flexible, skin-attachable, and wearable strain sensors due to their various potential applications. However, achieving strain sensors with both high sensitivity and high stretchability is still a grand challenge. Here, we propose highly sensitive and stretchable strain sensors based on the reversible microcrack formation in composite thin films. Controllable parallel microcracks are generated in graphite thin films coated on elastomer films. Sensors made of graphite thin films with short microcracks possess high gauge factors (maximum value of 522.6) and stretchability (ε ≥ 50%), whereas sensors with long microcracks show ultrahigh sensitivity (maximum value of 11,344) with limited stretchability (ε ≤ 50%). We demonstrate the high performance strain sensing of our sensors in both small and large strain sensing applications such as human physiological activity recognition, human body large motion capturing, vibration detection, pressure sensing, and soft robotics.