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Dielectric elastomer actuators (DEAs) are a promising technology for soft robotics. The use of DEAs has many advantages, including light weight, resilience, and fast response for its applications, such as grippers, artificial muscles, and heel strike generators. Grippers are commonly used as grasping devices. In this study, we focus on DEA applications and propose a technology to expand the applicability of a soft gripper. The advantages of gripper-based DEAs include light weight, fast response, and low cost. We fabricated soft grippers using multiple DEA layers. The grippers successfully held or gripped an object, and we investigated the response time of the grippers and their angle characteristics. We studied the relationship between the number of DEA layers and the performance of our grippers. Our experimental results show that the multi-layered DEAs have the potential to be strong grippers. [ABSTRACT FROM AUTHOR]

Dielectric elastomer actuators (DEAs) are energy efficient, compact, and operate silently. DEAs consist of an elastomer membrane sandwiched between two stretchable electrodes. Optimizing the quality of both the elastomer and the stretchable electrodes is essential to improve the DEAs performance. Herein, novel strategies are reported to achieve fast, reliable, and low‐cost fabrication of DEAs. The strategies utilize a soft brush to directly pattern carbon nanotube (CNT) powder on the elastomer membrane and tune the mechanical and surface‐adhesiveness characteristics of a polydimethylsiloxane (PDMS) membrane by altering the mixing ratio of the curing agent and base polymer. A uniaxial engineering tensile test on PDMS indicates that a softer material is formed when less curing agent is used. The softer PDMS has a sticky surface, which allows the CNT powder to be physically bound to the surface. Field‐emission scanning electron microscopy (FE‐SEM) images prove that the strong CNT network is formed on the surface of the elastomer. The electromechanical investigation also indicates that the electrical conductivity is improved for a stickier PDMS surface. The optimal performance of PDMS 30‐1 in static and cyclic DEA tests shows that the brushing of CNT combined with soft and sticky elastomer membranes can increase the DEA performance. [ABSTRACT FROM AUTHOR]

The previously reported gel and polymer actuators require external inputs, such as batteries, circuits, electronic circuits, etc., compared with autonomous motions produced by the living organisms. To realize the spontaneous motions, here, we propose to integrate a power supply, actuators, and control into a single-component self-oscillating hydrogel. We demonstrate self-actuating gel pumps driven by the oscillatory Belousov–Zhabotinsky (BZ) reaction without electronic components. We have developed the volume oscillation of gels synchronized with the BZ reaction (BZ gel). Since the self-actuating gel pumps are driven by chemo-mechanical energy from BZ gels, the self-actuating gel pumps don't require complex wiring designs, energy supply, and assembling. The mechanical work generated by BZ gels is extremely small. We formulated the thermodynamic cycle of BZ gels and maximized mechanical work. We found that pre-stretched BZ gel shows larger mechanical works. We physically separated the BZ gels and working fluid to create practical pumps. By using optimizing mechanical generated by BZ gels, we demonstrated the self-actuating gel pumps that transfer mechanical work through a stretchable elastomer membrane. [ABSTRACT FROM AUTHOR]

A piece of paper has many useful characteristics; it is affordable, lightweight, thin, strong, and highly absorbent. These features allow inexpensive and flexible devices to be fabricated easily and rapidly. We have proposed a new field, “paper mechatronics,” which merges printed robotics and paper electronics, and to realize electronic and mechanical systems by printing. Herein, we develop a method to print an actuator and a structure on a sheet of paper. A trilayer electrothermal actuator is printed to activate a printed robot. The paper self-folds along the printed pattern to form the three-dimensional (3-D) structure of the robot body. We also investigate important factors necessary to develop a printed robot. Experiments, including finite element analysis (FEA), confirm our bimetal modeling assumption for the printed actuator and improve the locomotive ability. The key factors in self-folding are paper thickness and humidity. Our findings can improve the reliability of printed robot designs. A self-folding A7-sized paper robot demonstrates locomotion at 10 mm per step. [ABSTRACT FROM PUBLISHER]

We propose a simple methodology to paint carbon nanotube (CNT) powder with a soft brush onto an elastomer. A large deformation of dielectric elastomer actuator (DEA) occurs according to the small constraint of the electrodes. Uniform painting with a soft brush leads to a stable deformation, as demonstrated by the results of multiple trials. Unexpectedly, painting with a soft brush results in aligned materials on the elastomer. The oriented materials demonstrate anisotropic mechanical and electronic properties. This simple methodology should help realize innovative DEA applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • DEA excitation technique is applied to a vibration experiment for apples. • Frequency responses of apples are obtained by DEA excitation and LDV measurement. • Mode shapes of apples are extracted due to an experimental modal analysis. • Firmness index is obtained by combining apple's resonance frequency and mass. • Effectiveness of the proposed method is validated by evaluating firmness index. A vibration experiment technique based on a dielectric elastomer actuator (DEA) excitation for apples is proposed. The characteristics of DEAs such as flexibility, lightweight, large deformation, and a fast response are conducive to vibration applications. Moreover, DEAs composed of soft rubber-like materials should be compatible with diverse objects. They can be applied to structures with curved surfaces and transfer excitation forces effectively. Herein, as an agricultural application, a DEA excitation technique is applied to assess the quality of apples, which have a spherical shape, using quality-related indices. Firmness is a function of the fruit's mass and its second-lowest resonance frequency. To evaluate the frequency responses and firmness of apples, we developed a vibration experiment system and the appropriate DEA composition. Then, the vibration responses of apples were measured by laser Doppler vibrometer (LDV) and evaluated by a spectrum analyzer to obtain the frequency responses. By assessing the firmness index of apples upon storing, we experimentally demonstrate the effectiveness of the proposed measurement technique based on the DEA excitation. [ABSTRACT FROM AUTHOR]

• DEA is applied to reduce multiple modes vibration of a membrane structure. • Frequency responses are measured with laser excitation/measurement system. • Controller for vibration control is designed based on H ∞ control method. • Vibration control experiment is conducted in a vacuum environment. • Effectiveness of the proposed method is validated by experiments. A vibration suppression technique for lightweight and flexible membrane structures is proposed using smart structure technology with a dielectric elastomer actuator (DEA). DEA, which is a lightweight flexible polynomial material with a large deformation and high response time, can easily be applied to membrane structures for vibration suppression over a wide frequency range. Herein, active vibration control for membrane structures with DEA is examined. A non-contact excitation system with a high-power Nd:YAG pulsed laser precisely measures the vibration responses of membrane structures. A laminated DEA is fabricated and attached to the membrane surface, generating a highly reproducible ideal impulse excitation. Then a digital control system is constructed with the laser excitation system. To demonstrate the effectiveness of the proposed method, vibration control experiments are conducted using a controller designed by H ∞ control theory with the identified membrane model in both atmospheric and vacuum environments. Image, graphical abstract [ABSTRACT FROM AUTHOR]

• DEA appropriate for vibration control at high frequencies is developed. • Appropriate layer of DEA generating effective control force is determined. • Actuator location and shape are optimized by modal strain energy of the structure. • The validity of the present method is demonstrated by control experiment. This study evaluates the basic characteristics of smart structures composed of dielectric elastomer actuators (DEAs) to suppress vibrations. A DEA, which is a lightweight, flexible polymer that can induce high deformations, should realize next-generation actuators. Additionally, DEA can achieve vibration control of structures with complex shapes or curved surfaces. Herein the performance and efficacy of DEAs are evaluated as an actuator for vibration control at high frequencies. First, the appropriate DEA structure is considered. Second, the control system for the smart structure using the DEA is modeled and designed as an actuator. Third, a method to determine DEA's optimum arrangement and shape is discussed by focusing on the structure's strain energy. Finally, a control simulation and a control experiment validate the vibration suppression effects and the efficacy of the DEA. Image, graphical abstract [ABSTRACT FROM AUTHOR]