Expanding the potential of its 3D counterpart, 4D Printing transcends into the 4th dimension – time. By allowing the printing of 3D objects that can change in shape and configuration over time, 4D Printing is set to transform aerospace structures, toys and other products we use in our everyday lives.
You can find more details at https://www.sutd.edu.sg/Research/Research-News/2013/5/4D-Printing