Influence of stretch-dependent permittivity on power generation output of dielectric elastomer

Dielectric elastomer (DE) energy harvesting device can be used as power source for battery-free or battery-maintenancefree wireless sensors, owing to the lightweight, high energy density and excellent deformability of DE. Previous research has shown that the power generation output of a DE device can be enhanced by increasing the permittivity of DE. However, the permittivity decreases with the mechanical stretching deformation. In this work, we investigated the influence of the stretch-dependent permittivity on power generation output of DE device. As a DE with increased permittivity, a composite material consisting of silicone elastomer base and rod-like titanium dioxide fillers (RTC) was used. Pure-silicone elastomer-based DE (PSR) was also used for comparison. The permittivity of the DE was measured under different stretching states and the lumped parameter model proposed by Schlögl et al. was used to fit the measurement results. Then the theoretical power generation output of DE device was simulated based on the fitting results. The results showed that the permittivities of RTC and PSR decreased by 28% and 17%, respectively when the DEs were uniaxially stretched to a stretch ratio of 5. The simulated power generation outputs of DE devices with RTC and PSR are similar, due to the large decrease in permittivity of RTC. The conclusion is that it is essential for enhancing power generation output of DE device not only to increase permittivity but also to weaken the stretch dependence on the permittivity because the permittivity decreases with stretching.