Soft unmanned flying objects have been developed to improve communication in areas where natural disasters occur. This article investigates the design, modeling, and control of an unmanned flying robot, different from classic flying robots which are based on electric motors, robots driven by soft actuators that have advantages of low noise, deformable property, and fast response. Untethered system based on dielectric elastomer actuators can be controlled to move, theory and experiments are presented to show the movement accompanied by large voltage-triggered deformation. We connect a dielectric elastomer balloon-shaped shell to an inelastic chamber which has larger volume and apply voltage to trigger one-layer or two-layer VHB membrane without causing electrical breakdown. The results show that buoyancy force in the air for helium balloon system is inversely proportional to the altitude when the flight system goes up. Compared with single-layer balloon shell, we also generalize the concept of multi-layer soft actuators that offer larger deformation. The larger the original volume of the untethered system is, the more mass can be controlled at the actuated state. Voltage-triggered controllable motion is appreciating with our designed structure.

Time-dependent dissipative behaviors of circular and spherical dielectric elastomer (DE) membranes were investigated, and viscoelastic models based on nonlinear theory were developed. Using these formulas, one can easily understand the electromechanical performance of DEs. By combining the Maxwell stress, mechanical stress, energy principle, Gent model (for circular membranes), and neo-Hookean model (for balloon-shaped membranes), we derived governing equations that describe membrane deformation. The voltage versus stretch curves of VHB-based thin films was N-shaped, and the peak applied voltage decreased as the viscoelastic stretch grew. Membranes with smaller original radii required shorter relaxation times. When the viscoelastic relaxation time was very short, the viscoelasticity could be negligible. There were clear differences between the theoretical analyses of circular and spherical DE membranes. For example, the radial stretch was different and the ideal gas law was used for DE balloons but not for circular films. Our experiments indicated large deformations of both types of DE membranes at 5 kV. However, electromechanical instability can appear over time. According to our theoretical analysis, a DE membrane can reach equilibrium after viscoelastic relaxation. The presence of viscoelasticity lowered the response speeds but increased the mean stretch of DE films. These models are expected to provide guidance for DE device design and application.

Soft electroactive materials including dielectric elastomer (DE) and polyacrylamide (PAM) hydrogel have recently been investigated, which can provide exciting opportunities for optical imaging and biomedical engineering. We propose a tunable liquid lens based on PAM hydrogels, and the miniature lens is also composed of a dielectric elastomer actuator (DEA) and an ionic liquid enclosed. When a biconvex lens is fabricated, a bubble needs to be voided by controlling the pressure. The lens DEA based on PAM electrodes has various resistances that decrease with the stretch. However, it is a constant of 0.49 Ω for the DEA coupling carbon grease electrodes. In a high voltage-driven state, the curvature radius of the lens increased. As a result, the focal length was tuned and enlarged. Computational models are derived for the soft-actuated liquid lens, which improves the existing related theory by detail. Especially, the relationship between voltage and focal length is deduced and verified by experiments. The computational models and experimental phenomena are consistent. Moreover, an increase in pre-stretch and voltage produces a wider tenability range. This study opens the soft electroactive biconvex lenses in potential optical healthcare rehabilitation and optical visual identification applications.