Realizing the Potential of 4D Printing
 
As additive manufacturing technology moves from research and prototyping to mainstream production, researchers are shifting their attention to producing structures that can transform in a pre-programmed way in response to a stimulus. The technology needed to create such products has been given the popular name “4D printing,” because it creates 3D objects that transform over time.

Programming structural deformations into physical objects is not new; researchers have been working with “memory materials” and “smart materials” for a long time.  One of the most popular technologies is known as shape memory alloy, where a change of temperature triggers a shape change. Other successful approaches use electro-active polymers, pressurized fluids or gasses, chemical stimulus and even a response to light that reshapes the final product after manufacture.

The head of MIT’s Self-Assembly Laboratory, Skylar Tibbits, pioneered today’s wave of 4D printing research a few years ago with expanding materials and simple deformations. A collaboration involving researchers from MIT’s Camera Culture group and those in the Self-Assembly Laboratory with the companies Stratasys and Autodesk  took this method further.

Their approach was to print 3D structures combining materials with different properties: one that remained rigid and another that expanded up to 200% of its original volume.  The expanding materials were placed strategically on the main structure to produce joints that stretched and folded like a “bendy straw” when activated by water, forming a broad range of shapes. For example, one 3D-printed shape resembled the initials “MIT,” but was designed to transform into another formation that looks like the initials “SAL,” which stand for Self-Assembly Laboratory.

Today, 4D printing is emerging as a further extension of additive manufacturing that has real commercial applications.  According to analysts at Grandview Research, the global 4D printing market is only estimated to reach $64.5 million by 2019, but from there, it’s expected to grow at a compound annual growth rate exceeding 33.2 percent through 2025. The research firm attributes the rapid take-off to rising demand in the defense, aerospace, automotive, and healthcare industries. North America is expected to emerge as a dominant region for 4D printing market by 2025 due to high investments in research and development.
 
According to Grandview Research analyst Priyanka Bansal, 4D printing isn’t so much a substitute for 3D printing technology, but a subset. It’s a technique that adds time as the fourth dimension to a 3D printed object.  4D printed objects are programmed to change physical dimensions upon application of external stimuli, and the processes for manufacturing the final product are essentially additive manufacturing processes applied in highly specialized ways, using special materials. The only difference comes with the products ability to change shape, while conventional 3D printed objects are static.

As an extension of 3D printing, 4D printing offers improved quality, efficiency, and performance capabilities. And while 3D printing can turn digital blueprints into physical objects layer by layer, 4D printing technology differs mostly in that it allows the 3D printed object to change its shape.

Although it will take some time for 4D printing to be available commercially, early forms of 4D printing are anticipated to comprise flexible objects designed in such a way that they can transform themselves when immersed in water or subjected to pressure, gravity, heat or air. These flexible objects can transform themselves into simple shapes such as a 3D cube, a complex art form or even into apparel from a mere cloth structure.
 
4D printing technology will also facilitate the development of electronic device manufacturing on plastic foils using organic thin-film transistors, while improved conducting polymers are being developed for organic electronics. Transistors developed with 4D printing techniques will not only have excellent current carrying capacity, but will also have chemical stability and low temperature processing.

Grandview believes there’s a great deal of potential for 4D printing in in the electronics industry, but there are several barriers, including its initial high cost as only a few companies are developing techniques to support it.

There’s no doubt 4D technology will bring significant changes to how products are designed by complementing traditional manufacturing techniques. However, it’s too early to tell what will happen in next five to 10 years or how 4D printing will impact the manufacturing value chain.
Given this trend, we offer the following forecasts for your consideration.

First, regardless of the industry where 4D printing is applied, one of its biggest potential benefits will be that parts could self-heal rather than requiring replacement if they fail or are damaged.  

Smart materials can be programmed to transform themselves in case there are certain unexpected changes in the actual dimensions or properties of the product. These materials can initiate preventive measures in case of any exposure to unusual environmental conditions such as excessive heat or excessive vibrations; consider LG’s incorporation of 4D technology into its smartphones, which can repair light scratches on the screen within 24 hours.  There would be limitations, however. Although the time taken for synthetic healing is much less than biological healing, it is still often more than 24 hours.   These materials may also stop self-healing after a certain point in time depending on the number of times the part has healed itself. The useful life totally depends on the material and its area of application. However, once the specific applications and solutions are developed, exact time limits can be predicted.

Second, 4D printing’s benefits for the supply chain will include easier transportation and less storage space.

Given that it can make a product in the form of a simple sheet before application of stimuli, the transportation of a large number of sheets would require negligible space and could easily fit into smaller vehicles to be later transformed into real 3D products.  4D printing will reduce transportation and handling costs to a large extent thereby offering immense benefits to the supply chain.  As a result the precautions and safety measures taken to transport many products to the end-user will be reduced greatly.

Third, this technology will not be considered “mainstream,” until 2025 or later.

Because 4D technology is in its nascent stage, there’s much work to be done before the tools are available for full-fledged commercialization. The Massachusetts Institute of Technology Self-Assembly Laboratory in collaboration with Stratasys, is currently developing materials that are capable of changing dimensions with the application of stimuli. These materials consist of carbon fibers and polymers that are flexible enough to undergo transformation.  And,

Fourth, since 4D printing is essentially an extension of 3D printing, the evolution of that technology can provide guidance on the impact of 4D printing. 

We can already see value chains becoming more automated, connected and decentralized.  And this is creating a growing need for innovative manufacturing techniques that can match up with the dynamic nature of tomorrow’s supply chains.  4D printing promises a growing library of smart materials that are conducive to efficient manufacturing with the ability to manufacture complex geometries.  We expect that over the next 10 to 15 years 4D printing will lead to significant re-shoring of manufacturing activities to countries with high wages like the U. S. and Germany.  Training a specialized workforce in printer operation & maintenance, as well as 4D digital design is of paramount importance to successful adoption of the technology.

References

1. Ebnonline.com. Are You Ready for 4D Printing? byGary Hilson.

http://www.ebnonline.com/author.asp?section_id=3479&doc_id=282868

2. The Conversation. December 18, 2014. Explainer: what is 4D printing? by Dan Raviv.

https://theconversation.com/explainer-what-is-4d-printing-35696

3. Science Advances. April 12 4D printing makes objects that assemble themselves when heated by By Alice Klein.  10.1126/sciadv.1602890
4. May 16, 2014. Forget the 3D Printer: 4D Printing Could Change Everything By Randy Rieland

http://www.smithsonianmag.com/innovation/Objects-That-Change-Shape-On-Their-Own-180951449/#ms5U7huX6waQ1x2M.99

5. Scientific Reports. August 23, 2016.  Shape-morphing composites with designed micro-architectures by Jennifer N. Rodriguez, Cheng Zhu, Eric B. Duoss, Thomas S. Wilson, Christopher M. Spadaccini, and James P. Lewick. 1038/srep27933

6. Nature Materials. January 25, 2016. Biomimetic 4D printing by Sydney Gladman, Elisabetta A. Matsumoto, Ralph G. Nuzzo, L. Mahadevan, Jennifer A. Lewis. 10.1038/nmat4544

7. Scientific Reports. September 21, 2015. Sequential Self-Folding Structures by 3D Printed Digital Shape Memory Polymers by Yiqi Mao, Kai Yu, Michael S. Isakov, Jiangtao Wu, Martin L. Dunn, H. Jerry Qi. 1038/srep13616