In this paper, we focus on water droplets and propose a novel method to control the movement of water droplets on surfaces such as paper. Most droplet movement methods based on the principle of electrowetting require a high density of electrodes to complex circuitry, and there are restrictions on the size of the droplet. In contrast, our method involves printing line-shaped electrodes on a paper-like sheet substrate and moving water droplets between these lines. The electrodes need not be densely arranged; they can be spaced several centimeters apart and water droplets can move between them. This not only greatly reduces the number of electrodes and simplifies the circuit, but also allows electrode placement with design and the ability to drive a wide range of water droplet sizes, from a few millimeters to several centimeters in diameter. This paper reports the details of the proposed method and presents several design examples.

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.