What

4D Printing offers a streamlined path from idea to full functionality.
With a single, multi-material print, a product or mechanism can be transformed from a 1D strand into any 3D shape, from a 2D surface into 3D shape or morph between different 3D shapes. Such transformations are facilitated by, e.g., heating, light, or swelling in a liquid, and by programming different sensitivity to, e.g., swelling into various parts of the designed geometry. These techniques offer adaptability and dynamic response for structures and systems of all sizes, and promises new possibilities for embedding programmability and simple decision making into non-electronic based materials. Potential applications include; robotics-like behavior without the reliance on complex electro-mechanical devices as well as adaptive products, garments or mechanisms that respond to user-demands and fluctuating environments.

Mechanical metamaterials are structured materials with mechanical properties defined by their structure rather than their composition.
By carefully designing their structure, materials with properties not found in nature, such as negative compressibility (contract when pulled) can be made. Novel developments include the use of elastic instabilities, origami-based materials and programmability, where a single materials function can be changed by pushing. The construction of such materials often relies on forms of (multimaterial) 3D and 4D printing.