Mimicking Self-Powered Piezoelectric Energy-Generating Behavior in Silicone Rubber Composites under Compressive and Tensile Strains

This study used a multifunctional and versatile silicone rubber, which can be vulcanized at room temperature, as the stretchable elastomeric matrix. Then, reinforcing fillers such as molybdenum disulfide (MoS2), diatomaceous earth (D.E.), and hybrids were used. Our results showed that the compressive modulus and tensile strength are improved after the addition of these reinforcing fillers. For example, the compressive modulus of the control sample was 1.93 MPa, and it increased to 6.1 MPa (D.E.), 2.47 MPa (MoS2), and 3.3 MPa for their hybrid at 20 phr. Similarly, the tensile strength of the control sample was 0.52 MPa, and it increased to 1.42 MPa (D.E.), 0.87 MPa (MoS2), and 0.83 MPa for their hybrid at 20 phr. We also conducted energy-harvesting experiments and found that the voltage output was higher for the compressive mode sets by 8–11 times than for the tensile mode sets, even under similar strain magnitudes. For instance, the output voltage at 30% strain for MoS2-filled composites was approximately 0.65 mV for compressive mode and 0.06 mV for tensile mode. Moreover, the energy harvesting was higher for hybrid-filled systems due to the synergistic effect than for D.E. or MoS2 as the only filler in the composites. For example, the output voltage was 1.22 mV (MoS2), 0.37 mV (D.E.), and 5.5 mV (hybrid) at 15 phr loading. Similarly, in real-time monitoring, compressive mode generated a higher voltage than tensile mode. Overall, the promising voltage output performance developed in the present work shows great potential for the future of smart health monitoring.