7. Towards 4D printing

Ground or inlay yarn can be a shape-memory thread, in which case it is sensitive to certain stimuli such as temperature, electric current or light. Its shape then evolves over time, which is known as 4D printing [10511] .

Figure 28 shows an example of a knitted fabric with shape-memory inlay insertion. Initially flat, the knitted fabric is deformed and then returns to its initial shape under the effect of temperature.