Stretchable Strain and Strain Rate Sensor Using Kirigami ‐Cut PVDF Film

Wearable sensor technology has recently received considerable interest because of the emergence of digital healthcare and its expanding markets. Wearable sensors require stretchability, biocompatibility, and high performance. In this study, stretchable strain sensors are designed and fabricated using a kirigami ‐cut polyvinylidene fluoride (PVDF) film. Further, the biocompatibility of PVDF is examined. Kirigami cutting can improve stretchability by 400% using the structural distortion of the cut parts. Compared to previously reported sensors, the developed sensor can measure the strain and strain rate simultaneously. The effect of strain and strain rate on the piezoelectric performance is analyzed. The output voltage increases exponentially with the strain, and a high strain rate results in high piezoelectric efficiency. The strain and strain rate can be detected by analyzing the sensor property, which illustrates the relationship between the voltage and voltage change rate. The sensing performance is evaluated using various kirigami patterns. Theoretical analysis reveals the dependence of output voltage on strain and strain rate. Finally, the developed sensor is successfully used as a wearable sensor for athlete rehabilitation and posture monitoring.