Soft-body manta ray-inspired bot uses surrounding water as one of the electrodes to contract silicone pockets of hydrogel that flap the wings. It’s speedy, strong, temperature robust, wireless and almost invisible. Developed by Tiefeng Li of Zhejiang University in Hangzhou, China. Article at ScienceMag and here’s the paper.
Source: Watch this robotic manta ray speed through the water