What Does the Future Hold for 3D & 4D Printing? Reviewing Current Processes & Ongoing Potential

Researchers come together to review both 3D and 4D printing, as well as exploring its ongoing potential in ‘Recent 3D and 4D intelligent printing technologies: a comparative review and future perspective.’

While both technologies offer great opportunity for industrial users to make and maintain functional parts and prototypes, 3D and 4D printing are a source of fascination around the world due to the ability to innovate at will, cutting out the middleman, and making new objects with new materials that may not have been possible previously.

The brief overview of relevant 3D printing methods

In the 4D realm, we see the progress being made from materials that may be less flexible to those that are able to shift with their environment—and according to the user’s needs. The authors not only delve further into fundamentals and development (especially in the evolution from 3D to 4D) but also perform comparative analysis regarding both forms of digital fabrication.

From the inception of 3D printing in the 80’s via Chuck Hull to its emergence in the mainstream and now integration into many fields—from robotics to tissue engineering, electronics, and more—the authors follow 3D printing, pointing out correctly that it is currently ‘still in the active stage of industrial innovation.’ Designers and engineers are able to take advantage of a wide variety of benefits—even including applications like fashion and jewelry.

Schematic illustration of 1D, 2D, 3D, and 4D concepts

General schematic overview of 3D printing technology with solid, liquid and power-based patterns (a) FDM; (b) SLS; (c) SLA (Sources: https://www.custompartnet.com)

While advantages such as affordability, accessibility, and greater efficiency in production are being enjoyed by many, there are still challenges regarding materials in applications like soft robotics and aerospace. With the ability to shift form while under pressure from temperature or moisture, 4D printed smart materials avail the user of greater flexibility and versatility.

“Compared  to  3D  printing,  4D  printing  updates  the  concept  of  change  in  the  printed  configuration  over  time,  which  relies  on  environmental  stimuli.  Therefore,  4D  printed  structures  should  be  fully  preprogrammed  using  time-dependent  deformations  of  products,” state the authors.

4D printing relies on:

• Suitable hardware
• Stimulus-responsive material
• Stimuli
• Interactive mechanisms
• Mathematical modeling

SWOT analysis of a). 3D printing technology; b). 4D printing technology.

Smart materials and the ability to deform and then return to their natural shape mean that 4D printing is suitable for not only for robotics but also self-repairing of materials like hydrogels, piping, and other materials which may be related to reusability and recycling.

The illustration of shapeshifting by self-folding using water absorption materials: (a) 1D to 3D41; (b) 2D to 3D41

While one of the obstacles in 3D printing is the general need to fabricate items with only one material, 4D printing is beginning to emerge as a forerunner in applications like the medical and engineering fields.

3D printed models in the medical area (a) 3D printed heart; (b) 3D printed skull (Source: https://3dprintingindustry.com/news; sketchucation.com)

3D printing is still becoming increasingly popular, however, for use in the military field, creating weaponry and allowing for better maintenance of parts. 3D printed models are improving treatment for patients and can be used as extremely helpful pre-planning devices for surgery. Various hardware has also been created for extrusion of food like chocolate and pancake batter.

As for 4D printing, the authors expect that it will be used to create more advanced smart materials that can transform environmentally as users require, offer ‘self-controllable functions,’ expand longevity in products, and promote greater complexity in structures.

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