We are all familiar with the concept of 3D printing but have you ever heard about 4D printing? What do you think 4D printing is? Any guesses? We are well aware that 3D printing, or additive manufacturing, is the creation of a three-dimensional object from a digital 3D model. So, is 4D printing the creation of a 4D object? If so, what even is a 4D object?
What is 4D printing?
It is the introduction of the fourth dimension to the 3D printing technology. With the introduction of this new dimension, 3D printed objects can change their shape on their own by the influence of external stimuli, like heat, light, electricity, magnetic field, etc.
By integrating this dimension of time, printed objects can change their shape dynamically depending on the requirements of a situation, without the need for any electromechanical parts. This marvel of changing shape exhibited by 3D printed objects is an attribute of the material to transform in response to specific stimuli. It does not entail any human mediation to assist the same.
To put it in simple words, 4D printing is the remodeling of 3D printing where materials with distinctive properties are used to print objects that can change shape post-production.
Ascension of 4D Printing from 3D Printing
3D printing is considered to be one of the most disruptive innovations in the field of modern manufacturing. It has radically changed the way components and equipment are manufactured in the industry. It enables manufacturers and researchers to produce complex structures, which are deemed impossible with traditional methods.
The increasing need for flexible objects in various disciplines kindled the origin of 4D printing. Conventional 3D printing manufactures meta-material structures from a single material. Meta-material structures are a combination of several different materials that produce superimposed structural responses when activated by external stimuli. The congruent printing of different materials is expected to form anisotropy, which will enable the produced structure to modify itself by bending, elongating, twisting, and corrugating along its axes.
The key difference between 3D printing and 4D printing is the materials used to print structures.
4D Printing Materials and Technologies
Research Fields in 4D Printing
In 4D printing, a code is added to the printed object that specifies instructions about how the change in shape will be executed when triggered by a stimulus. This preprogramming step facilitates the creation of smart, responsive 4D objects.
Smart Material revolves around the deformation mechanism and is synthesized based on the responses of materials to various external stimuli.
Equipment Design deals with developing advanced printer technology. It is expected to be capable of printing several distinct materials congruently.
Mathematical Modeling is essential in understanding the functional structures of 4D printed objects. It prognosticates the deformation, forward prediction, and formation, backward prediction, processes of an object responding to stimuli.
Materials used for 4D printing are classified on the basis of the external stimuli they respond to.
Thermo Responsive Materials
These work on the mechanism of the Shape Memory Effect (SME) and are classified into- Shape Memory Alloys (SMA), Shape Memory Polymers (SMP), Shape Memory Hybrids (SMH), Shape Memory Ceramics (SMC), and Shape Memory Gels (SMG).
Most of the researchers prefer SMPs because it is easy to print on them. They form and deform when subjected to external heat or thermal energy.
Moisture Responsive Materials
These react to contact with water or moisture and are widely favored by researchers as water is available in abundance. ‘Hydrogel’ is one of the smart materials in this category because it responds vigorously to water. Hydrogel can increase its size up to 200% of its original volume when subjected to water.
Photo/Electro/Magneto Responsive Materials
These respond to light, current, and magnetic fields. For instance, when photo responsive chromophores are saturated with polymer gels, they swell up and absorb natural light when exposed to it. Likewise, when current is applied to an object comprising ethanol, it evaporates. This increases its volume and expands the overall matrix. Magnetic nanoparticles are embedded in the printed object to achieve magnetic control.
Although 4D printing is a promising technology, it still needs to overcome several technological obstacles. Till then, here’s hoping that all our remarkable researchers will overcome these obstacles soon and we’ll be able to modify our 3D printed objects on our own accord!