In the decades that followed, 3D printing moved from a niche prototyping tool into a mainstream technology with applications in medicine, aerospace, robotics, and industrial manufacturing. Engineers now use it to produce prosthetics, dental implants, aircraft components, and even experimental human tissue. After nearly forty years of steady evolution, the field has entered a new phase: 4D printing.
The emerging approach introduces time as a functional design element to printed objects. In simple terms, the process allows printed objects to change their shape, properties and functionality over time.
How 4D printing works
At its core, 4D printing builds on 3D printing by incorporating programmable smart materials that respond to external stimuli. Instead of producing static components, the process yields structures that can bend, fold, stretch, expand, or contract when exposed to changes in temperature, light, moisture, or pH.
Once printed, these materials can change their structure, properties and functions over time (the fourth dimension), allowing the object to adapt to its surroundings or even assemble itself.
MIT researchers, who introduced the idea of 4D printing in 2013, showed that a flat-printed structure could curl into a cube when placed in hot water. Meanwhile, a separate 2021 study demonstrated how a medical stent could automatically expand at body temperature.
By using the same approach, researchers at the Harbin Institute of Technology (HIT) recently created multi-material, multi-responsive and multi-shape memory polymer (SMP) gradient metamaterials.
“We’re moving from static designs to materials that can sense, decide, and act,” Jinsong Leng, PhD, an HIT professor and co-author of the study, pointed out in a statement.
Potential applications
The ability to program behavior into matter has implications across engineering and manufacturing. In medicine, 4D-printed stents remain compact during insertion but expand automatically once positioned, reducing the need for additional surgical intervention.
At the same time, researchers are exploring drug delivery systems that release medication only when triggered by a specific condition, such as an increase in body temperature during fever. This could potentially make treatments both safer and more effective.
Construction and aerospace are two other major sectors where 4D printing could prove useful. The technique could enable self-assembling structures that not only drastically reduce labor but also significantly cut costs.
Furthermore, 4D printing could result in the production of flexible soft robots that perform tasks traditional robots are not able to.
Consumer products could also benefit from 4D additive manufacturing. Some applications include shoes that adapt to walking conditions, self-assembling furniture, color-changing novelty items and ultimately, adaptive clothing that responds to body shape.
Benefits of 4D printing
Similarly to most emerging technologies, 4D printing offers a number of exciting possibilities. One key advantage of the process is computational folding. It allows parts too large for a 3D printer to be produced in compact, secondary forms.
In addition, 4D printing offers greater efficiency than conventional 3D printing by reducing energy consumption, material use, production time and costs.
It’s also a highly adaptable technology. This means that rather than producing static, single-purpose objects, it develops components that can respond and reconfigure in real time.
Despite the need for further research, 4D printing also shows strong potential to improve sustainability in civil engineering trough the use of renewable, bio-based materials. It also helps minimize waste, reduces errors and prevents product loss in manufacturing processes.
Another great advantage is that it’s faster than many conventional production methods and requires less manual effort. Its automation eliminates the need for external mechanisms like motors or hinges, allowing for more efficient, compact designs.
However, perhaps one of its greatest strengths is the use of smart materials that respond to external stimuli. By adding the element of time, 4D printing enables structures to change and adapt long after they’ve been produced.
The drawbacks behind the process
However, despite the technology’s promising potential, it still remains in the early stages of development and has yet to reach full commercial maturity. The field is still new, with limited research and guidelines available to support development.
At the same time, because 4D-printed objects are designed to move and respond to changes, the design process is more complex than in traditional 3D printing.
This is because the technology requires sophisticated programming and complex algorithms to control how materials react to stimuli.
Data suggests that smart materials like shape memory polymers and hydrogels remain costly and challenging to scale. At the same time, 4D printing systems remain limited in availability and capability. Questions about their long-term durability under repeated stimuli also remain unanswered.
The process also faces accuracy issues, as fluctuations in parameter optimization can impact control over shape and size. Ultimately, with no established industry standards, scaling the technology for widespread use remains a great challenge.
The future of 4D printing
Despite its challenges, 4D printing is widely regarded as a promising technology, with ongoing research and strong support from experts. Researchers remain optimistic about its future impact across multiple industries.
“Materials science is evolving,” Leng stated, adding that the future is much more than just building stronger or lighter structures. “It’s about creating materials that can think and perform multiple jobs at once.”
According to Polaris Market Research, a leading provider of industry insights, the 4D printing market is steadily expanding, fueled primarily by advancements in the aerospace and defense sectors.
Moreover the adoption of shape memory technology for self-positioning systems is a emerging as a crucial factor in pushing the market forward.
The global 4D printing market was valued at USD 156.8 million in 2023, and it is projected to reach USD 1.3 billion by 2030. This represents a compound annual growth rate (CAGR) of 35.8 percent over the forecast period.
For engineers, the takeaway is clear: 4D printing is not simply a novelty or an incremental upgrade to 3D printing. By embedding adaptability into the very materials of design, it represents a shift toward manufacturing components that don’t just exist in time, but change with it.