Boneless soft robotic fingers cannot apply concentrated forces to pinch a delicate object. This letter reports a three-dimensional design of dielectric elastomer fingers with higher flexural stiffness and close to 90° voltage-controllable bending for object gripping and pinching. It makes use of tension arch flexures to elevate a pre-stretched dielectric elastomer actuator (DEA) into a roof shape and thus magnifies the tension-induced moment, 40 times higher than a flat DEA does, to bend a stiff base frame. Such fingers make normally close-grippers to lift a payload 8–9 times their weight. They also make normally open grippers that pinch a highly deformable raw egg yolk.

An ornithopter hovers, darts, turns rapidly, and pulls up from a dive by blending paraglider, airplane, and helicopter characteristics.

Beyond printing text on paper, inkjet printing methods have recently been applied to print passive electrical and optical microparts, such as conductors, resistors, solder bumps and polymeric micro lenses. They are also useful to print micro-electro-mechanical systems (MEMS) as sub-millimeter sensor and actuator arrays, such as multifunctional skins applicable to robotic application and ambient monitoring. This paper presents the latest review of a few successful cases of printable MEMS devices. This review shows that inkjet printing is good for printing two-dimensional or surface MEMS devices from a small unit to an array over a large area. In the future, three-dimensional printing of multi-materials, from metal, plastic, to ceramic, will open the possibility of realizing more variety and function of a large-areal MEMS array, for a mobile electro-mechanical systems.

Most membrane-type acoustic absorbers for low-frequency sound attenuation are applicable only at a fixed resonant frequency for a narrow bandwidth. Tuning of the acoustic absorption spectrum is desired to match the varying noises. This letter presents a micro-perforated dielectric elastomer actuator (MPDEA) to make a broader-band acoustic absorber electrically tunable. Voltage activation of the MPDEA reduces the membrane tension and hole size and thus enables the active shifting of the acoustic absorption spectrum. Such a membrane tuning method does not require discrete mechanical parts as for the cavity tuning method. Also presented are the analytical models to predict the voltage-induced hole size change and acoustic characteristics of MPDEA.