4D Printing (4DP): Technology of the future

Additive Manufacturing or 3D Printing has evolved into a viable, trusted & tangible, technological alternative to a host of traditional manufacturing & fabrication methods. However, lurking in the shadows of this technology, a new development is slowly & steadily acquiring shape & potential to disrupt major industries in a far more radical way than 3D Printing has done so far. Adding the ‘fourth’ dimension of ‘Time’ to the usual three dimensions of length, breadth & height, in an additive manufacturing process has resulted in the discovery of ‘4D Printing’.

The question of ‘what is 4D Printing?’ can hence be answered as follows: Printing, manufacturing or fabricating objects, tools, parts, in a way that allows them to alter shape, size, form & structure, due to external influences in form of energy, like light, temperature or other environmental stimuli, is known as 4D Printing. Majority of research in 4DP is dedicated to combining ‘technology & design’, aimed at inventing self-assembling & programmable material technologies, which have the potential to revolutionize Construction, Manufacturing, product performance & assembly.

Differentiating between 3DP (3D Printing) & 4DP is hence simple. 3DP works by printing layer upon layer of material of a 2D structure, in a path from the bottom to the top, generating a 3D volume or object. 4DP repeats the same process, however, the difference is the materials used to print these objects. 4DP requires advanced & specially programmed materials that change shape & structure, in response to any changes in their environments.  

One example of these advanced & programmable materials is a Shape Memory Polymer (SMP). SMPs have the ability of large-scale elastic deformation, in response to environmental stimuli. Figure 1 shows us an example of this phenomenon. When a certain change in temperature is induced, the 4D printed inanimate flower object; made of SMP material, changes shape in response to rising temperatures. As is evident in Figure 1, different levels of temperature changes, induce different deformations of the structure.

Different smart printing materials can be used to deliver desired changes in model structures. SMPs as shown in Figure 1, work on the mechanism of the Shape Memory Effect (SME). They fall under the category of Thermo Responsive Materials: materials that change size, shape when thermal energy is applied as a stimulus. Various such materials are currently being developed, namely Shape Memory Alloys (SMA), Shape Memory Hybrids (SMH), Shape Memory Ceramics (SMC), and Shape Memory Gels (SMG). SMPs are currently the preferred materials for 4DP, as they are currently far easier to develop & print with.