A highly sensitive wearable flexible strain sensor based on polycrystalline MoS2 thin film

The present study investigates the piezoresistive properties of polycrystalline MoS(2)film for strain-sensing applications. The gauge factor (GF) of the flexible MoS(2)device (MoS2/PET) has been calculated to be 102 +/- 5 in the stress range from similar to 7 MPa to similar to 14 MPa. In addition, to improve the sensing stress range, the flexible strain sensors are encapsulated by SU-8. The effect of encapsulation layer thickness is reflected in the GF, which is attributed to the shifting of the neutral axis. However, the calculated GF is constant in the higher stress range, 80 +/- 2 and 12 +/- 1 for 2 mu m and 10 mu m thick SU-8, respectively. Herein, we report a cost-effective and scalable approach to fabricate large-area polycrystalline MoS2-based flexible sensors for a wider stress range. The encapsulated devices remained undistorted and intact for stress values beyond 14 MPa. Further, we demonstrate the durability of the fabricated sensors with body movements, such as hand gestures, for all the three types of strain sensor.