Enhanced-sensitivity and highly flexible stress/strain sensor based on PZT nanowires-modified graphene with wide range carrier mobility

Abstract

Flexible stress/strain sensors have widespread applications including healthy monitoring systems, smart robotics, and wearable devices. Graphene, a promising carbon material with several excellent properties, is widely used in flexible stress/strain sensors. Creating a graphene-based pressure sensor with improved sensitivity remains highly challenging owing to the difficulty in widening the band gap of graphene. Herein, a novel heterostructural enhanced-sensitivity stress/strain sensor composed of two-dimensional (2D) graphene and one-dimensional (1D) lead zirconate titanate (PZT) nanowires as the sensitivity material, was fabricated. The polarized charges generated by the piezoelectric nanowires under mechanical stress acted as ionized impurities to increase the scattering carriers of graphene, thereby changing its conductivity; additionally, the high piezoelectric property of nanowires provided numerous polarized charges, resulting in increased scattering carriers. Therefore, the as-fabricated device has an enhanced sensitivity of 2.95 × 10−2 kPa−1, which is higher than that of the pure graphene-based pressure sensor. In particular, the fabricated sensor can detect bending strain, such as the bending and straightening of a finger, and the angle of opening a book. Furthermore, the device can record handwritten signals that can be used as indicators of biometric information. Thus, the fabricated device provides a viable and convenient approach for application in multi-functional electronic wearable devices.