Araucaria leaf-inspired surface (IMAGE) City University of Hong Kong Caption By mimicking its natural structure, the team designed the Araucaria leaf-inspired surface with 3D ratchets, which enable different water-ethanol mixtures of varying surface tension to spread in three directions: forwards, backwards and bidirectionally. Credit City University of Hong Kong Usage Restrictions Image must be used with appropriate caption and credit. License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.