Imagine a 3D-printed object that does not simply sit in one shape but can change its form when heated. One part could stretch while another contracts, allowing the object to move, bend or transform without motors, gears or complicated mechanical systems.
This idea could become a reality thanks to a new development in shape-changing soft materials. Researchers have created a new type of 3D-printable material that can be programmed to either elongate or contract when heated, simply by changing how it is printed.
The breakthrough could open new possibilities for soft robotics, wearable technology, artificial muscles, medical devices and advanced 4D printing.
The Problem With Conventional 3D Printing
Materials that respond to heat are already being studied for applications in soft robotics and biomedical devices. Among them are liquid crystal elastomers (LCEs)—rubber-like materials containing specially organized molecules.
When these materials are heated, their internal molecular arrangement changes. This causes the material to change shape.
However, conventional extrusion-based 3D printing creates an important limitation.
During printing, molecules inside each filament generally become aligned in one direction. As a result, the printed filament tends to have only one main type of movement when heated.
In simple terms, if the material is programmed to contract along one direction, it cannot easily be programmed to perform the opposite movement within the same printing process.
This limits how complex and useful these shape-changing structures can become.
A New Type of 3D-Printable Ink
A research team led by Professor Suk-kyun Ahn of Pusan National University in South Korea, together with researchers from Oak Ridge National Laboratory in the United States, has developed a new approach to overcome this problem.
The researchers created what they describe as the first 3D-printable smectic liquid crystal elastomer ink capable of switching molecular alignment during printing.
The key idea is surprisingly simple: change the printing conditions.
By adjusting the printing speed or temperature, the researchers could change the direction in which molecules inside the material became aligned.
That meant the same material could be programmed to behave differently when heated.
One printing condition could make a filament contract, while another could make it elongate.
Professor Ahn explained that the work demonstrates the ability to switch molecular alignment between two perpendicular directions using a single 3D-printable smectic LCE ink.
How Does the Material Work?
To understand the breakthrough, it helps to look at what happens inside the material.
Liquid crystal elastomers contain molecules that can organize themselves in particular directions. These molecular arrangements influence how the material responds to external stimuli such as heat.
In traditional LCE printing, molecular alignment is strongly connected to the direction in which the printer deposits the material.
The new technique takes advantage of the special properties of smectic liquid crystal materials.
When researchers changed the printing speed or temperature, the molecules responded differently during the printing process. Their orientation could switch between two directions that were perpendicular to each other.
This molecular change ultimately determined how the printed structure moved when heated.
Therefore, the researchers could effectively program movement into the material while printing it.
Scientists Used Several Techniques to Understand the Process
The research team did not rely on printing experiments alone.
They combined direct ink writing with several scientific techniques to understand why the molecular alignment changed.
They used rheological measurements to study how the ink behaves while flowing through the printer nozzle.
They also used wide-angle X-ray scattering to examine the arrangement and orientation of molecules inside the material.
In addition, molecular dynamics simulations helped the researchers understand the molecular-level processes responsible for the switching behavior.
Together, these methods helped explain how changes in printing conditions could control the internal structure of the LCE.
Printing Objects That Can Change Shape
After understanding the mechanism, the researchers demonstrated that the technology could be used to create more complicated structures.
They printed both two-dimensional and three-dimensional objects, including lattices, curved structures and surfaces capable of changing their topography.
This is important because it shows that the technique is not limited to making simple straight filaments.
Instead, the researchers can combine different molecular orientations within printed structures to create programmable movements.
For example, different sections of one structure could potentially respond differently to the same amount of heat.
One region could contract while another expands, causing the entire object to bend, twist or change its surface shape.
A Step Toward Smarter Soft Robots
One of the most exciting applications could be soft robotics.
Traditional robots often depend on rigid motors, gears and joints. Soft robots, in contrast, can use flexible materials that deform to create movement.
A heat-responsive LCE could act somewhat like an artificial muscle. Instead of using a conventional motor, a robotic component could change its shape when heated.
Because the new printing technique allows both expansion and contraction to be programmed, designers could potentially create more complicated movements without adding numerous mechanical components.
This could make future soft robots simpler, lighter and more adaptable.
Potential Uses Beyond Robotics
The technology could have applications far beyond robots.
Researchers suggest that these programmable materials could be used to create artificial muscles, wearable devices and reconfigurable surfaces.
For example, a wearable device could potentially change its shape to improve comfort or fit.
Another possibility is haptic technology. Surfaces could change their texture or shape to create physical sensations for users.
The technology could also help create adaptive surfaces that alter their texture or geometry in response to environmental conditions.
One interesting possibility is using shape-changing surfaces to regulate aerodynamic drag. A surface could potentially modify its structure depending on the desired aerodynamic performance.
The approach may also have potential for minimally invasive medical tools. Devices could be inserted into the body in a compact form and later change shape when exposed to a suitable stimulus.
Repeated Heating Did Not Destroy the Performance
Another important result was the material's ability to undergo repeated heating and cooling cycles.
The researchers found that the printed structures maintained stable performance during repeated thermal cycles.
This is important for practical applications because a material intended to function as an actuator or wearable component may need to change shape many times.
However, the researchers emphasize that the work is still at the laboratory stage.
The experiments were conducted using one specific smectic LCE formulation, and additional research will be needed to determine whether the technique can be adapted to other materials and scaled up for large-scale manufacturing.
The Future of 4D Printing
Traditional 3D printing creates objects with a predetermined shape. 4D printing adds another dimension: time.
A 4D-printed object can be designed to change its shape or properties after it has been manufactured, usually in response to heat, moisture, light or another stimulus.
The new LCE printing strategy could take this concept a step further by allowing scientists to program different movements into different parts of the same printed structure.
Instead of simply printing an object, engineers could essentially print its future movement.
Professor Ahn believes that over the next five to ten years, this type of technology could help 3D-printed objects move beyond simply holding a fixed shape.
They could potentially change shape, respond to their surroundings and perform useful functions.
The study represents an important step toward that future. By controlling molecular alignment through printing speed and temperature, researchers have found a relatively simple way to give soft materials programmable movement.
If the technique can eventually be expanded to more materials and larger manufacturing processes, the boundary between 3D printing and robotics could become increasingly blurred.
Reference: Lee, JH., Kim, K.P., Ding, L. et al. Alignment switching in 3D-printed smectic liquid crystal elastomers. Nat Commun (2026). https://doi.org/10.1038/s41467-026-75368-z
Comments
Post a Comment