Scheme5
The 4-D material changes shape in response to water. The grey side of the material in the image absorbs water faster than the blue side, causing it to bend into a “C” shape. Credit: Yu Bin Lee.
The 4-D material changes shape in response to water. The grey side of the material in the image absorbs water faster than the blue side, causing it to bend into a “C” shape. Credit: Yu Bin Lee.