4D Printing - Introduction

4D Printing Technology

It has been more than 30 years since the first patent was issued for Stereolithography Apparatus (SLA), invented by Charles (Chuck) Hall in the 1980´s. Initially known as Rapid Prototyping technology, with further advancement now called additive manufacturing or 3D printing technology. (Industry 3., 2014) 

Nowadays, 3D printing machine is used not just in industry for production but also in school, households, and offices. As the price for normal desktop 3D printer has fallen below 10k rupees, the affordable price allows unlimited opportunities for an individual to print their own customized toys, household appliances and tools. 

However, there is always something more than can be done with the current ongoing technology. 3D printed materials can be more flexible and useful, the structures of the material can transform in a pre-programmed way in response to any external stimulus. 

In general, self-changing structure of 3D printed part after post-process is called 4D printing process. (Stratasys, 4D Printing, 2014) The term 4D printing is developed in a collaboration between MIT´s Self-Assembly Lab and Stratasys education and R&D department. In February 2013, Skylar Tibbits, co-director and founder of the Self-Assembly Lab located at MIT´s International Design Center, unveiled the technology “4D printing” during a talk at TED conference held in Long Beach, California. (TED, 2013) 4D technology is still in the early phase of research and development. This technology has been used only in a few labs or prototyping facilities. In the current scenario, one can´t just order and buy a “4D printer”.

As of 2017, MIT´s Self-Assembly Lab, 3D printing manufacturer Stratasys and 3D software company Autodesk are the key players in the development of 4D printing technology. 

What separates 4D Printing Technology from 3D Printing Technology?

Considering how quickly 3D printing technology prototypes the model and eventually can be used in mass production, this technology is surely the next big thing in the field of manufacturing. But the expansion of this technology even further leads to 4D printing.

4D printing technology involves creating objects with special multi-material components that eventually change after reacting with external properties or sometimes on their own without external involvement. In both 3D and 4D printing processes, additive manufacturing is involved to create new products. The only difference is the time with material changing its properties.

1.) Time Factor - 

Time is an element for extra dimension in 3D printing that makes 4D printing. In order to get the final structure, it takes time to transform from an initial shape. The 3D printed object also requires some time in order to heal or cooling time. However, 4D printed parts start acting only after exposure to external energy. In general, 3D printed parts are ready to use after printed whereas, 4D printed parts are not completely ready for its motive even after print in done.

2.) Material - 

The most common materials used by the 3D printer are Nylon, ABS plastic, Resin, Wax and Polycarbonate. These traditional materials are easily available in the market, hence printing using these materials is easy. However, 4D printing technology uses Smart materials.

Smart materials are multi-materials with one or more properties that can undergo a transformation in a controlled fashion by external energy. Usually, Smart materials are piezoelectric, electrostrictive, magnetostrictive, thermoelectric, and shape memory alloys.

In the below table you can see how external energy affect the smart materials - 

Shape memory alloys are strong, hard, tough, very good conductivity but expensive. CuAl-Ni alloy, Ni-Ti alloy, Cu-Au-Zn alloy are few lists of smart metal alloys. Here, Cu refers to Copper, Al is Aluminum, Ni is Nickel, Ti is Titanium, Au is Gold and Zn refers to Zinc metal.

Biomolecular Self-Assembly - A process by which disordered parts build an ordered structure through only local action.
Example- Polio Virus; when it has shaken, got assembled by itself. As you can see in the below image


Programmable Matter - Matter that has the ability to change its physical properties in a programmable fashion, based upon user input or autonomous sensing.
        These are High-volume nanoscale assembly.
        They have the ability to inexpensively produce millimeter-scale units that integrate computing, sensing, actuation, and locomotion mechanisms.
        A collection of these nanoscale units is programmable matter.

3.) Simple Manufacturing - 

The products are directly built from a standardized digital file and all the computer-controlled processes help reducing time for expertise as well as human interaction required to create an object.

While the object is being printed, the process often remains unmonitored allowing objects to be built overnight without human interference.

Similar to the process, 4D printing processes are becoming even simpler than 3D printing technology. The simple-looking structure can be printed and then with the help of an external activating agent, it can transform into a complex, large functional structure.

Furthermore, the self-assembly structure senses and reacts physically with the surrounding environment itself without any human involvement.

4.) Hardware - 

After material selection, hardware has a key role in the printing process. Depending upon technology and requirement, there are various 3D printing machines available in the market both for home use and production. Form 1+ printer, which is based on the Stereolithography process and Mojo from Stratasys operates using the Fused Deposition Molding technique.

Stratasys' Connex the multi-material 3D printer has added the capability of embedded transformation from one structure to another. This multi-material processing technology allows researchers to map multiple material properties into a single structure carrying features of parent material with water-absorbing properties to activate the self-assembly process.

Water acting as external activating factor, this technique promises broad possibilities for embedding programmability for non-electronic based design. Similarly, RoVa4D Full-color Blender 3D printer from ORD solutions, (solutions, 2016) allows affordable full-color multi-material desktop printing.

5.) Software

Need to say that current software tools are behind hardware capabilities. The new advancement in the field of the printing industry has forced researchers and engineers to develop new types of software tools with capabilities that go beyond CAD, CAM, Solidworks, or other modeling software. With the emerging new idea such as bio-printing, multi material printing, 4D printing, and electronics printing, there is a demand for software which can incorporate all those processes. 

Product designs in the industrial sector are constrained by the limitations of the machines. Although the process inside the production facility is faster and quicker in comparison to 3D or 4D printing technology.

SWOT analysis of 4D Printing Technology

A SWOT analysis is carried out for any company, person, or product. This process involves specifying the objective of any project identifying internal and external factor that is suitable and unsuitable to achieve the project goal.

The analysis of 4D printing is useful to identify strengths, weaknesses, opportunities, and threats related components shown in Table 4, for 4D printing technology. 

STRENGTHS (internal factors, positive)

The efficiency of material and manufacturing process 
Positive market growth forecast 
Multi-color print 
Multi-material print 
Smart material (programmable material) 
Based upon multi-material 3D printing.

WEAKNESS (internal factors, negative)

New technology in the field of 3D printing
Expensive smart material and limited 
Expensive hardware (printer) that may restrict public from using it 
Accuracy in shape change, complex shapes 
Requires specialized personnel and controlled environment.

OPPORTUNITIES (external factors, positive)

Helps logistic problems, transportation 
Helpful in extreme places i.e. war zone, space 
Useful for implants in the medical field 
Concept of smart city, buildings & structures 
5D printing.

THREATS (external factors, negative)

Machine compatibility 
Public safety and health problems 
Impact on the environment 
Intellectual property rights -copyright, patent, trademark 
System vulnerable to software hack, piracy 
Ethical issues.

Application Area and Future Development

4D printing technology has the potential to change the current business environment. Future advancement of this mechanism depends and remains focused on a variety of capabilities. For example, the current process that allows 4D printed structure to expand when exposed to water and when the structure is allowed to dry, it tends to unfold and regain its original shape.

The self-changing ability of material leads to a range of applications in various industries. It is essential for any business to reduce manufacturing costs and increase profit to stay in a fiercely competitive environment.

The concept of 4D printing technology along with 3D printing provides a platform for new business ideas that can adapt and compete for the current market trend by lowering capital requirement, time-efficient, less space for holding inventory, and increasing efficiency of the business.

4D printing promotes maintaining a sustainable environment as the self-transforming capability of the 4D printed item allows after use disposition, changing back to the original shape.

Application Areas - 

1. Medical Research

There have been successful implants of those 4D printed structures, which needs to be biocompatible with the patient’s immune system and able to adapt the external surrounding tissues within the body.

Most likely, the upcoming future of 4D printing technology will include all types of implants and reconstructive surgery. Beyond helping patients with respiratory issues, researchers are exploring their use to correct human skeletal deformation such as facial reconstruction, rebuilding ears.
2. Aeronautics and Robotics

Designing roots requires the ability to develop responsive and highly sensitive parts. 4D printing will allow those machinery far more advanced adaptive and dynamic ability to perform complex tasks effectively. A team of researchers at MIT and Harvard University developed origami robots, which are reconfigurable robots capable of folding themselves into arbitrary shapes and crawling away. The prototype robot was made up of printable parts entirely. (Hardesty, 2014)

3. Military applications

As technology allows the materials to change its shape, military equipment, cars, and fabrics could enable them to alter its camouflage. Military advancements with 4D printing technology would develop coating material in an automobile that changes its structure to cope with the humid environment and corrosion. Similarly, the transformation of tires depending upon road and weather conditions.

4. Furniture and House appliances

People are much more familiar with IKEA furniture which comes in parts and packed. It takes lots of time and effort for normal customers to assemble and make ready. However, one could imagine the relief when that flat packaged furniture self assembles and the furniture is ready to use without any hassle. Similarly, the self-disassembling of furniture while moving from one location is comforting. Along with the time saving, it could help people get rid of complex assembling process and mistakes.

5. Fashion

The idea of clothes and trainers adjusting their shape and function in response to the external environment and comforting the user sounds fascinating. Fitting perfectly upon pressure being applied or gears becoming waterproof itself when raining. 

Expanding/Contracting Water Pipes - 4D Printed Objects

A good example of the potentially inevitable revolution of 4D printing in the field of construction can be smart water pipes, which have the ability to adjust and assemble themselves as per the changing water pressure and temperature. As the pipes adapt and adjust independently, no need for any digging preventing internal damages, this mechanism will help in easy and cost-effective maintenance. 


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