Four-dimensional printing can print many 3D parts and objects that 3D printing can’t [ 19] The color [ 20 ], volume [ 21 ], and shape [ 22] of these printed objects can grow or shrink with environmen…
ing can’t [19] The color [20], volume [21], and shape [22] of these printed objects can grow or shrink with environmental conditions and stimuli, such as light, water, air and temper- ature [12] .