Inflatable systems have been attracting attention in the field of interaction design. Conventional tabletop-sized pneumatic systems tend to be complex because they require bulky and noisy equipment. Therefore, several liquid-to-gas phase change actuators that use vaporization have been proposed. But these actuators have problems with controllability, reusability, and reconfigurability. In this study, we propose InflatableMod, novel inflatable modules based on the efficient control of liquid-to-gas phase change actuators. These are designed with a compact circuit that has a liquid transfer function to feed the required amount of low-boiling-point liquid into the pouch and a heating function to inflate the pouch by the volume change. This approach allows for a compact, silent, and untethered inflatable system. It is also possible to create an untethered and reconfigurable multi-inflatable system because each module is synchronized. In this paper, we propose the design of the modules, evaluate their performance, and present application scenarios.

Physical interfaces that change appearance by controlling transparency have attracted attention for wide applicability. However, many existing methods are limited to planar objects, and it is difficult to control transparency in three-dimensional objects and to control transparency continuously. In this study, we propose a novel method to control the transparency of three-dimensional objects by utilizing the mechanical emulsification phenomenon of liquid. This approach is to fill the object with two transparent liquids that are liquid-liquid phase separated and agitate the liquids inside the object to make them cloudy and control their transparency. By using electrohydrodynamic (EHD) pumps, which can be freely positioned inside the object, to agitate the liquid, it is possible to control the transparency of complex three-dimensional objects. Continuous control is also achieved by changing the ratio of the two liquids. In this paper, we describe the details of proposed method for controlling the transparency and show application scenarios.

In recent years, actuators that handle fluids such as gases and liquids have been attracting attention for their applications in soft robots and shape-changing interfaces. In the field of HCI, there have been various inflatable prototyping tools that utilize air control, however, very few tools for liquid control have been developed. In this study, we propose HydroMod, new constructive modules that can easily generate liquid flow and programmatically control liquid flow, with the aim of lowering the barrier to entry for prototyping with liquids. HydroMod consists of palm-sized small modules, which can generate liquid flow with the electrohydrodynamics (EHD) phenomenon by simply connecting the modules. Moreover, users can configure and control the flow path by simply recombining the modules. In this paper, we propose the design of the modules, evaluate the performance of HydroMod as a fluid system, and also show the possible application scenarios of fluid prototyping using this system.

Underwater robots have a variety of potential uses, including marine resource research, ecological research, and disaster relief. Most of the underwater robots currently in practical use have screw propulsion systems, which have several noises, collision, and entrainment problems. There is a lot of research on underwater robots using soft actuators to solve these problems. However, current soft actuators have disadvantages, such as the need for special fluids, pressure sources, and high voltage circuits. Therefore, we have developed a soft-skin actuator based on magnetohydrodynamics (MHD). The soft-skin MHD actuator is made of soft material and the structure is prepared as thin, which allows it to attach to the surface of an object, including curved surfaces, to provide the object with a propulsive function in the sea. Since it has no moving parts, it does not generate mechanical noise, and there is no danger of entrapment. Because it can pump seawater directly, it does not require a special working fluid, and its structure is simple and easy to miniaturize. This paper investigates the thrust and power consumption of the developed soft-skin MHD actuator when attached to a flat surface. As a result, we obtained a thrust of 1.37 mN from a single soft-skin MHD actuator with a maximum power of about 140 W. We also measured the thrust force by attaching it to a curved surface. We obtained a higher thrust on a curved surface by adjusting the crossing of the magnetic field and the current than when using a flat surface. We developed an untethered robot that can remove oil from the sea using soft-skin MHD actuators. We demonstrated the adaptability of the soft-skin MHD actuator by attaching it to a commercial underwater camera weighing about 253.5 g and providing propulsion.

Designing and manufacturing actuators using soft materials are among the most important subjects for future robotics. In nature, animals made by soft tissues such as the octopus have attracted the attention of the robotics community in the last years. Suckers (or suction cups) are one of the most important and peculiar organs of the octopus body, giving it the ability to apply high forces on the external environment. The integration of suction cups in soft robots can enhance their ability to manipulate objects and interact with the environment similarly to what the octopus does. However, artificial suction cups are currently actuated using fluid pressure so most of them require external compressors, which will greatly increase the size of the soft robot. In this work, we proposed the use of the ElectroHydroDynamics (EHD) principle to actuate a suction cup. EHD is a fluidic phenomenon coupled with electrochemical reaction that can induce pressure through the application of a high-intensity electric field. We succeeded in developing a suction cup driven by EHD keeping the whole structure extremely simple, fabricated by using a 3D printer and a cutting plotter. We can control the adhesion of the suction cup by controlling the direction of the fluidic flow in our EHD pump. Thanks to a symmetrical arrangement of the electrodes, composed by plates parallel to the direction of the channel, we can change the direction of the flow by changing the sign of the applied voltage. We obtained the pressure of 643 Pa in one unit of EHD pump and pressure of 1428 Pa in five units of EHD pump applying 6 kV. The suction cup actuator was able to hold and release a 2.86 g piece of paper. We propose the soft actuator driven by the EHD pump, and expand the possibility to miniaturize the size of soft robots.