A Flexible Pressure Sensor Based on Magnetron Sputtered MoS₂

Although two-dimensional (2D) layered molybdenum disulfide (MoS₂) has widespread electrical applications in catalysis, energy storage, and photodetection, there are few reports available regarding sputtered MoS₂ for piezoresistive sensors. In this research, we found that the resistance of magnetron sputtered MoS₂ on a flexible substrate changed significantly and regularly when pressure was applied. Scanning electron microscope (SEM) and atomic force microscope (AFM) images revealed an MoS₂ micro-grain-like structure comprising nano-scale particles with grooves between the particles. Chemical characterization data confirmed the successful growth of amorphous MoS₂ on a polydimethylsiloxane (PDMS) substrate. A micro-thickness film flexible sensor was designed and fabricated. In particular, the sensor with a 1.5 μm thick polydimethylsiloxane (PDMS) substrate exhibited the best resistance performance, displaying a maximum ΔR/R of 70.39 with a piezoresistive coefficient as high as 866.89 MPa^-1 while the pressure was 0.46 MPa. A proposed flexible pressure sensor based on an MoS₂ film was also successfully used as a wearable pressure sensor to measure plantar pressure and demonstrated good repeatability. The results showed that the thin film pressure sensor had good piezoresistive performance and high sensitivity.