Design of Electrohydrodynamic Devices with Consideration of Electrostatic Energy

Abstract

The importance of actuators that can be integrated with flexible robot structures and mechanisms has increased in recent years with the advance of soft robotics. In particular, electrohydrodynamic (EHD) actuators, which have expandable integrability to adapt to the flexible motion of soft robots, have received much attention in the field of soft robotics. Studies have deepened the understanding of steady states of EHD phenomena but nonsteady states are not well understood. We herein observe the development process of fluid in a microchannel adopting a Schlieren technique with the aid of a high-speed camera. In addition, we analyze the behavior of fluid flow in a microchannel that is designed to have pairs of parallel plate electrodes adopting a computational fluid dynamics technique. Results indicate the importance of considering flow generated by electrostatic energy, which tends to be ignored in constructing and evaluating EHD devices, and by the body force generated by the ion-drag force. By considering these effects, we estimate the development process of EHD flow and confirm the importance of considering the generation of vortices and their interactions inside the microchannel during the development of EHD devices.

Sustainable Elastomers for Actuators: “Green” Synthetic Approaches and Material Properties

“…Creating polymer actuators is a broad area of research that is not limited to elastomeric materials. There are many research trends in this field: pressurized fluid actuators [ 9 ], hydrogel-based actuators [ 10 ], shape memory alloy/polymers (SMAs/SMPs) [ 11 , 12 , 13 ], wearable actuators [ 14 ], electroactive polymer actuators [ 15 , 16 ], dielectric elastomer actuators (DEAs) [ 17 , 18 , 19 ], and actuators based on stimuli-responsive materials that could be triggered by temperature [ 20 , 21 ], light [ 22 , 23 , 24 ], pressure [ 25 ], pH [ 26 ], and magnetic [ 27 ] or electric fields [ 28 , 29 , 30 , 31 ]. Different types of actuators and materials used for their design are presented in Figure 1 [ 32 ].…”

Ultrafast Photothermal Actuators with a Large Helical Curvature Based on Ultrathin GO and Biaxially Oriented PE Films

“…Bending motions and spiral deformations are very common in nature, such as the movement of pine cones, tendrils of plants, seed pods, wheat awns, and so on. − More interestingly, some of the actuations and deformations are very fast and great. For example, the Venus flytrap and Aldrovanda vesiculosa close their snap traps (opening angle ∼50°) within only 0.1 and 0.02 s, respectively, so their lobes (modified leaves) have an amazing bending speeding of 500–2500° s –1 . − Another unique species is Erodium (Geraniaceae): the awns of its fruit exhibit a high degree of coiling deformations in the drying process, producing 8 ± 1 turns of spiral within 10 min, with a large curvature of 18–20 cm –1 (the radius of the spirals is only 0.05–0.055 cm). , In recent years, biomimetic actuators and bionic robots have emerged and become an active interdisciplinary research field, − and many types of artificial actuators (thermo-, photo-, moisture-, solvent-, pH-induced) have been developed. − However, most of their response speeds are relatively slow. The actuating time is usually 5 s to 2 min for electrothermal actuators, − 7 s to 5 min for photoinduced actuators, − 10 s to 5 min for humidity actuators, ,− and 1–120 min for hydrogel-based actuators (pH-, solvent-induced). ,− Additionally, the deformations of these actuators are not large either, and most of their bending angles do not exceed 180° and the curvature does not exceed 6 cm –1 . ,,,− It is difficult for the existing artificial actuators to accomplish superfast actuations and large-curvature deformations comparable to those of the wonderful actuators in nature.…”

Influence of Electrohydrodynamic Flows on the Intensification of the Heat and Mass Exchange Processes. Part I. Electrohydrodynamic Flows and Characteristics of Single-Stage Electrohydrodynamic Pumps

“…Этот оптический метод основан на визуализации отклонения светового луча, пересекающего градиенты показателя преломления в прозрачной среде, например из-за неоднородности плотности жидкости. Oн применяется при исследовании процессов тепло-и массопереноса [17,18], смешения газов или жидкостей, явления распространения пламени или изучении сверхзвуковых потоков, где градиенты плотности достаточны для большого отклонения света. Шлирен-метод не вносит какие-либо неоднородности в среду, в отличие от микрочастиц, используемых для визуализации ЭГД-течений [6,9], позволяет выявить характер течения, дает представление о диссипативных (возвратных) течениях и турбулизации потока, оказывающих влияние на эффективность работы насоса.…”