Researchers demonstrate soft insect-scale aquabots using electrified hydrogel actuators

[Courtesy of the Ministry of Scicence and ICT]

SEOUL – South Korean researchers have developed insect-scale soft “aquabots” using high-performance electrified hydrogel actuators driven by low voltages that can be applied to various small environmental crawlers and medical devices. The aquabot integrated with an on-board control unit demonstrated maneuverability with fast locomotion speed.

Electroactive soft actuators operating at low voltage and low power with a high degree of portability and performance are desirable for next-generation robotics based on soft materials. Hydrogels represent an exciting class of reactive soft material, but their inherently slow nature of water diffusion into the hydrogel matrix limits practical applications.

A research team led by Cho Jin-han, professor of chemical and biological engineering at Korea University, and Koh Je-sung, professor of mechanical engineering at Ajou University, introduced an electroactive hydrogel actuator based on crumpled nanomembrane electrodes driven by electroosmosis which overcame the drawbacks of prior hydrogel actuators, such as slow response time, low power density and poor controllability.

An assembly approach, termed “capillarity-assisted in situ assembly of metal nanoparticles” has been developed to fabricate a hydrogel actuator, providing an easy and efficient route for the formation of a wrinkled nanomembrane layer with a large surface area and a porous structure on the hydrogel surface.

The hydrogel coated with wrinkled nanomembrane electrodes (WNE) showed high electrical conductivity, mechanical flexibility, and high actuation performance with 3.0 volts or less based on efficient electroosmosis pumping inside of the hydrogel body.

The high performance of WNE actuators has been demonstrated by making untethered soft aquabots with a body size of 2 cm. “Our soft aquabots based on WNE actuators could be built without any high-voltage converters and conventional transmission systems, which significantly limited the miniaturization of soft robots,” the team said in a paper published on the Science website. Robotics, a peer-reviewed scientific journal.

“We believe our approach could provide a basis for developing lightweight, high-performance soft actuators and small-scale robots that require a variety of movements under electrical stimuli.”

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