Inchworm based on the voltage actuation of dielectric elastomer actuators (DEAs) are amongst the simplest types of robots. We demonstrate a proof-of-concept inchworm robot that incorporates a few aligned fibers to suppress undesirable actuator bulging and more effectively convert the bending of a dielectric elastomer unimorph to forward motion. Finite element modeling confirms the role of the fibers in suppressing bulging but also shows that a threshold actuation voltage is required to convert the unimorph bending to forward motion of the inchworm. Based on the modeling results for unimorphs having different fiber spacing a simple inchworm is constructed and locomotion is demonstrated for actuation above the threshold voltage. Although not optimized, the inchworm illustrates the importance of using selectively positioned stiffening fibers as well as elastomers having lower viscoelastic losses.
Electrically tunable adaptive lenses provide several advantages over traditional lens assemblies in terms of compactness, speed, efficiency, and flexibility. We present an elastomer-liquid lens system which makes use of an in-line, transparent electroactive polymer actuator. The lens has two liquid-filled cavities enclosed within two frames, with two passive outer elastomer membranes and an internal transparent electroactive membrane. Advantages of the lens design over existing systems include large apertures, flexibility in choosing the starting lens curvature, and electrode encapsulation with a dielectric liquid. A lens power change up to 40 diopters, corresponding to focal length variation up to 300%, was recorded during actuation, with a response time on the order of tens of milliseconds.
Dielectric elastomer generators (DEGs) are attractive candidates for harvesting electrical energy from mechanical work since they comprise relatively few moving parts and large elastomer sheets can be mass produced. Successfully demonstrations of the DEG prototypes have been reported from a diverse of energy sources, including ocean waves, wind, flowing water and human movement. The energy densities achieved, however, are still small compared with theoretical predictions. We show that significant improvements in energy density (550 J/kg with an efficiency of 22.1%), can be achieved using an equi-biaxial mechanical loading configuration, one that produces uniform deformation and maximizes the capacitance changes. Analysis of the energy dissipations indicates that mechanical losses, which are caused by the viscous losses both within the acrylic elastomer and within the thread materials used for the load transfer assembly, limits the energy conversion efficiency of the DEG. Addressing these losses is suggested to increase the energy conversion efficiency of the DEG.
Conference Committee Involvement (1)
SPIE Smart Structures/NDE - Electroactive Polymer Actuators and Devices (EAPAD) XV - Session chair