A joint research team including Professor Jin-han Cho of Korea University (left) and Professor Je-seong Koh of Ajou University developed a flexible actuator and micro-water robot using hydrogel electrodes and published it on the 27th of October in the international scientific journal ‘Science Robotics’.
A flexible actuator has been developed that can be used for a small, flexible water robot. Flexible actuators are actuators made of soft materials, not rigid, bulky motors.
The Ministry of Science and ICT announced on the 26th that a joint research team including Professor Jin-han Cho of the Department of Chemical and Biotechnology at Korea University and Professor Ko Je-seong of the Department of Mechanical Engineering at Ajou University had developed an ultra-small water robot with a hydrogel flexible actuator. The research results were published in the October 27th issue of the international scientific journal ‘Science Robotics’.
Hydrogel is attracting attention as a core material for next-generation micro-robot actuators because of its excellent functionality and stimuli response to the surrounding environment. However, because the existing hydrogel actuator uses the principle that the osmotic pressure changes according to an external stimulus, the driving speed is slow and movement control is difficult, so there are limitations in applying it to complex robot systems. Using electrical stimulation can improve performance, such as increasing the driving speed and moving flexibly, but it was difficult to efficiently apply electrical stimulation due to the high moisture content of the hydrogel.
The research team increased the electrical conductivity by uniformly coating the electrode layer with gold nanoparticles on the surface of the hydrogel. In addition, by utilizing the shrinkage phenomenon of the hydrogel, the wrinkle structure of the electrode layer was induced to secure mechanical elasticity. Electroosmosis occurred when a magnetic field was applied to the inside of the hydrogel made in this way. Electroosmosis is a phenomenon in which an ionic fluid moves according to a potential difference, which can induce deformation of the hydrogel, which means that it can be used as a flexible actuator.
Existing flexible actuators required a voltage higher than 1000V, but the flexible actuator developed by the research team was able to operate at voltages as low as 3V or less. In terms of performance, it has more than 100 times the energy density and more than 10 times the power density. In particular, it can exhibit high performance even with a small battery, making it easy to manufacture ultra-small and ultra-light robots. The research team applied this to create an ultra-small water robot that can operate under water.
Professor Cho said, “We expect that the low-voltage and low-power flexible actuator can be applied to various small environmental exploration robots and medical devices.” Professor Koh also said, “The hydrogel electrode manufacturing technology is a technology that can make functional hydrogels into electronic materials more easily, and can be introduced into various next-generation material research.”
