In this blog post, we’ll explore the concept and operating principles of 4D printing, from its early research to the current state of the technology, and examine how it can be applied in various fields such as architecture, healthcare, defense, and fashion.
What is 4D printing, which goes beyond 3D printing?
We often see construction sites where aging pipes are being replaced. There are also many cases where the walls of dilapidated houses are torn down and rebuilt. The common thread in these examples is that materials must be replaced once they’ve aged or become dysfunctional. This leads to inefficient use of resources. If, like a scene from a movie, the diameter of a drainage pipe could change according to the flow rate, or a wall could bend or stiffen in response to changes in load, we could save the time, effort, and capital required to replace aging machinery or building materials. 4D printing technology, which has been researched primarily at MIT, demonstrates this potential. The concept of 4D printing was first proposed in 2013 by Skyler Tivitz of MIT, and since then, active research has been conducted to combine smart materials—which change their shape or physical properties over time in response to stimuli—with additive manufacturing technology. So, what exactly is 4D printing? Let’s explore the principles behind the technology, its current state of development, and its future prospects.
The 3D printers we are familiar with produce three-dimensional objects based on computer-designed data. The advantage of 3D printing is that it allows for the relatively free production of objects with complex shapes. However, when creating large objects that exceed the printer’s build volume or when multiple parts need to be combined, the process of assembling the printed parts requires significant time and effort. One technology that can address these limitations in a different way is 4D printing. The “fourth dimension” in 4D printing refers to the addition of time-dependent changes to the three-dimensional space we are familiar with. In other words, rather than simply being created once and retaining a fixed shape, the material printed by the printer reacts to external stimuli—such as temperature, water, light, electricity, and humidity—over time, transforming into a pre-designed shape or function.
Consider the following example: If a plastic rod is designed so that each segment absorbs water at a different rate and is then placed in water, the varying degrees of expansion in each section cause the rod to bend in a specific direction. In this way, a structure printed as a one-dimensional line can be designed to transform into a three-dimensional structure upon receiving an external stimulus. This process, in which an ordered, higher-dimensional structure forms from a pre-designed assembly without the need for direct external manipulation of individual components, is called self-assembly technology. 4D printing can be defined as a technology that combines additive manufacturing with various smart materials—such as shape-memory polymers, hydrogels, and liquid crystal elastomers—capable of enabling such self-assembly or shape changes. While materials such as shape-memory alloys initially garnered attention, current research on 4D printing is broadly exploring various stimulus-responsive materials, including shape-memory polymers. Meanwhile, at the microscopic level, phenomena such as protein folding or cellular shape changes—where structures form in response to the surrounding environment at the molecular and cellular levels—can be observed, and research is also being conducted on stimulus-responsive micro- and nanostructures for drug delivery. However, directly applying the principles of self-assembly from the microscopic world to the fabrication of macroscopic structures was no easy task. This is particularly true because, as the size of the material increases, it becomes more difficult to precisely control deformation and stably form the desired structure.
How has self-assembly technology evolved?
Amid this, researchers at MIT and other institutions have opened up new possibilities by advancing research that combines 3D printing with self-folding technology. In particular, in 2014, an MIT research team unveiled a robot that folds itself into a pre-programmed shape when heat is generated by an electric current, using materials with built-in electrical circuits and shape-memory polymers. The structure, fabricated in a flat state, transforms into a three-dimensional robot as it folds sequentially in response to heat. The researchers integrated the necessary electrical circuits and actuators into the structure itself, enabling the robot to take shape on its own without the need for manual assembly from external components. This was a significant research example demonstrating that 4D printing and self-assembly technologies can be utilized to create actual mechanical structures.
However, current 4D printing technology cannot yet be considered fully commercialized across all fields. As of 2026, research continues to focus on enhancing material reactivity, ensuring the precision and repeatability of shape changes, and scaling up production. In particular, key challenges remain, such as precisely controlling the speed and extent of self-deformation, designing materials that respond to multiple stimuli simultaneously, and ensuring the durability and reliability required to maintain performance even after repeated shape changes. Recent research has focused on material extrusion and photopolymerization as the primary 4D printing methods, and efforts continue to achieve more complex and precise shape changes using various smart materials—including shape-memory polymers—and multi-material systems. Therefore, while 4D printing is already being used in various laboratories and research settings to create a wide range of prototypes and functional structures, there are still many challenges to overcome before it can be widely adopted in general industrial settings.
How can 4D printing be utilized in the field of architecture?
If suitable materials and manufacturing technologies continue to advance, in what other fields could 4D printing be used? First, consider the field of architecture. The cells and tissues that make up our bodies change in form and function in response to external influences and exhibit biological properties that allow them to repair damaged structures under certain conditions. Similarly, if building materials were given the ability to self-assemble or change their shape and physical properties in response to the environment, it would be possible to create architectural structures in ways entirely different from today’s methods. For example, we could envision building materials where a structure manufactured in a flat state transforms into a desired shape upon receiving a specific stimulus on-site, or where the structure’s form changes in response to environmental factors such as temperature and humidity. While these functions are currently implemented primarily using specific smart materials like shape-memory polymers, future research may evolve toward creating structures that adapt to the environment by combining these materials with a variety of construction materials, including wood and metal. However, endowing wood or metal itself with autonomous programming capabilities—similar to those of living organisms—is not yet a common technology at the current level of development; rather, research is needed to achieve the desired responses by combining materials and structures.
What possibilities does this hold for the medical field?
Second is the medical field.
Research is already underway on drug delivery systems that respond to the in vivo environment and medical devices utilizing shape-memory materials. With 4D printing, it may be possible to fabricate medical structures that transform into specific shapes or perform necessary functions inside a patient’s body. Future research could focus on microstructures that detect tumors or deliver drugs to specific sites, medical devices that conform to the shape of blood vessels or tissues, and self-transforming tissue scaffolds. Furthermore, 4D printing may be utilized to create bio-organs or tissue-engineering scaffolds that adapt to their environment. In fact, recent research in the field of tissue engineering is focused on fabricating 4D structures that respond to the biological environment using shape-memory polymers and shape-memory hydrogels. Beyond this, the potential applications of smart materials that respond to their environment and change shape on their own are being explored in various fields, including defense, aerospace, automotive, electronics, soft robotics, and fashion. However, applications such as micro-robots that directly locate and remove tumors or reconnect severed blood vessels are not yet widely used technologies and should be viewed as long-term research goals.
Can 4D printing reduce resource waste?
We have thus briefly explored the past, present, and future of 4D printing technology. This technology overcomes the limitations of conventional 3D printing—which maintains the shape and function of a printed object in a fixed state—and demonstrates the potential to create structures whose form and physical properties change in response to the external environment. Of course, 4D printing technology still faces many challenges. First, even now, it is not easy to precisely control the process and speed of self-assembly or shape transformation. Additionally, we must address the fact that smart materials, once transformed, may find it difficult to return completely to their previous state, or their performance may degrade during repeated transformation processes. The durability and stability of materials, the scalability of manufacturing processes for mass production, and the predictability and precise control of shape changes are also critical challenges. If these shortcomings are addressed and suitable materials are developed, 4D printing could help transform products into the required shapes and contribute to reducing the resources needed for assembly, maintenance, and repair. In modern society, where we must use the Earth’s limited resources efficiently, 4D printing technology has the potential to evolve into a technology that opens up new possibilities for conventional manufacturing methods.
