Over 30 years ago, one of the earliest forms of 3D printing technology was filed for a patent by Chuck Hull. Since then innovations and modifications to this emerging field has made possible its applications to a wide range of industries, from manufacturing to biomedical science.
by Deborah Seah
From 3D printing pens to industrial sized 3D printing machines able to produce components in the manufacturing line, the technology has progressed from its early and slightly inaccessible ancestor, stereolithography, to a variety of formats that are even available as children’s toys. This technology has come a long way since being recognized as an industrial process.
3D printing also known as additive manufacturing is the process of constructing three-dimensional objects from a 2D digital format – the computer-aided design (CAD) or 3D digital design. Much like the conventional printers used to reproduce text and images on paper, the 3D printer requires input of ink or filaments made of the desired material that could be a type of plastic, metal, or carbon fibre. During the process the filament is deposited to a platform and combined or solidified based on commands from a computer to create a 3D object.
Stereolithography was coined by Chuck Hull in 1984 when he filed for a patent for the process. In this method, 3D objects are created using thin “printed” layers of material, which is then cured using ultraviolet light, beginning at the bottom layer to the top layer of the object. An earlier form of the modern layered approach was first invented by a Japanese researcher, Hideo Kodama, where ultraviolet light is used to cure photosensitive polymers to produce solid 3D objects.
Commercialization of the technology came after the first patent was granted in 1986, when Chuck Hull co-founded the world’s first 3D printing company, 3D Systems. Leveraging on the technology, stereolithography found success in the automotive industry which propelled the use of 3D printing at the industrial level. Continued advancements and innovation to this technology has widened the scope of its application in many industries.
Applications of 3D printing
Next few decades after its first discovery, 3D printing technology has stretched its versatility to cover a variety of applications. Despite its initial high cost of materials in the earlier years, improvements in the technology has driven down costs making it more accessible as well as a more cost-effective option across industries.
Customizations, rapid manufacturing, prototyping, and product development are some applications of 3D printing technology in the manufacturing industry. Additive manufacturing has been applied in many formats, some of which include cloud-based additive manufacturing, mass customization, rapid manufacturing, rapid prototyping, research, food manufacturing, and agile tooling. With its cost-effective and developments in higher-quality methods, 3D printing will continue to shape manufacturing processes throughout different scopes.
2. Medicine and Healthcare
Medical and healthcare industries are not ones to shy away from technological advancements. Particularly those that enable improvements in processes and encourage ease of learning for healthcare professionals. One of earliest adoptions of 3D printing in the medical field came from the mid-1990s, it was in the form of 3D printing-centric therapies using anatomical modelling for bony reconstructive surgery planning. These models allow surgeons to practice on with features close to a live patients’ to be more prepared for real life situations and deliver better patient care. Virtual rendering of surgical processes coupled with guidance of 3D printed, personalized instruments has benefitted many areas of surgery. This include total joint replacement and craniomaxillofacial reconstruction.
Another aspect of healthcare which has shown great success in the use of 3D printing is the printing of medical devices and orthopaedic implants. 3D printed prosthetics is also now made possible for the use of rehabilitation.
Additive manufacturing in the pharmaceutical field has also made advancements through the years. The first 3D printed tablet was first approved by the FDA in August 2015. The process involved binder-jetting 3D printing into a powder bed of the drug to produce the tablets.
3D printing rapidly expanded to the home-use market, with many hobbyists, and artists embracing the technology for creating objects of their own making. A simple 3D printing machine is now easily purchased from various e-commerce websites at affordable prices. With many different types and grades of a 3D printing machine available to the masses, its no wonder the technology is now making its way to the classrooms of school students. Bringing it to classroom environment allows students to tap into their creative minds and develop tools and simple devices from 3D printing.
3D Printing vs Bioprinting
The concept is the same, however execution of the process is mechanically different. Both processes ultimately use a specified material to build a structure as defined by a digital render of the object. The difference lies in the use of materials and the type of structures that are produced. No doubt 3D printing has much use and applicability in the medical and healthcare industries in producing surgical assistive instruments and orthopaedic replacements. 3D printers use a variety of materials such as plastics, polymer resin, and metal. Bioprinters on the other had use living cells as the ink for printing biological materials.
Bioprinting is also a type of additive manufacturing process which uses biomaterials for the purpose of tissue engineering or formulation of regenerative medicine. The resulting product of bioprinting usually comes in the form of a scaffold which aims to mimic live tissues. Similar to 3D printing, bioprinting is also based on layering of biological components in a precise manner. Controlling the microenvironment through growth factors and stimulants, the placement of these biological constituents is formed into a 3D structure.
Advancements in Bioprinting
Research in bioprinting techniques and methods has led to the development of many potential applications. A prominent application is the bioprinting of artificial blood vessels and vascular grafts. At the Wyss Institute, Harvard University, a multidisciplinary research group has formulated a method able to generate vascularized tissues made of living human cells. This method demonstrated to be ten-fold thicker when compared to previously engineered tissues. The team developed the method to be customizable, using a silicone mould for mounting the printed tissue on a chip. Printing of the vasculature involved the use of vascular channels containing living endothelial cells in silicone ink and a self-supporting ink made of mesenchymal stem cells (MSCs) which is layered over. Stabilization of the structure after printing uses a liquid made up of fibroblasts and extracellular matrix to fill up the gaps within the bio-printed tissue.
Through further research, bioprinting has been developed to be applied in other areas of medicine. In a recent study by researchers from the Singapore University of Technology and Design (SUTD) and their research collaborators from the Nanyang Technological University, Singapore (NTU), made an in-depth analysis of leveraging on 3D bioprinting for skeletal muscle tissue. Through the analysis considerations were made in relation to designs of skeletal muscle models as well as the parameters that influence its construct. Some of which include the matrix, cells, and structures associated with myogenesis (formation of muscle tissue).
"In recent years, with bio-printed skeletal muscle demonstrating great flexibility in constructing functional tissue models, almost every organ of the human body can be bio-printed. While our review paper seeks to maximize the potential in 3D skeletal muscle tissue models, we expect our work to also inspire deeper research in eventually replicating native muscle," said principal investigator Prof Chua Chee Kai from SUTD.
Noted in the team’s review, despite the many advancements there are still challenges that have yet to overcome for the tissue models to fully replicate original tissue. Ensuring proper nerve structure and vascularization of the muscle model is also essential for bio-printed muscle to be fully function.
In a separate research from SUTD, researchers worked to address the challenge of controlling the parameters to successfully direct the differentiation of stem cells to produce cardiomyocytes (heart cells). They were able to achieve this through 3D bio-printed micro-scaled physical devices with finely tuned structures.
"The field of additive manufacturing is evolving at an unrivalled pace. We are seeing levels of precision, speed and cost that were inconceivable just a few years ago. What we have demonstrated is that 3D printing has now reached the point of geometrical accuracy where it is able to control the outcome of stem cell differentiation. And in doing so, we are propelling regenerative medicine to further advance alongside the accelerated rate of the additive manufacturing industry," said principal investigator Assistant Professor Javier G. Fernandez from SUTD.
"The use of 3D printing in biology has been strongly focused on the printing of artificial tissues using cell laden cells, to build artificial organs 'piece by piece'. Now, we have demonstrated that 3D printing has the potential for it to be used in a bio-inspired approach in which we can control cells to grow in a lab just as they grow in vivo," added first author Rupambika Das, PhD student from SUTD.
Aside from the medical field, bioprinting has also extended its reach to the food industry, additive manufacturing of food is now growing in popularity given the harmful environmental impact by animal food sources. This futuristic concept might seem years away is actually happening right now. Companies such as Memphis Meats and BeeHex have been dabbling in the 3D food printing space to revolutionize how food is produced.
At a very rapid pace, advancements in 3D printing has progressed to cover many aspects of different industries. Its wide range of potential further innovation has piqued the interest of researchers and companies across many disciplines. No doubt 3D printing has become one of the most revolutionary innovations of our time.
- Das R, Fernandez JG. Additive manufacturing enables production of de novo cardiomyocytes by controlling embryoid body aggregation. Bioprinting. 2020;20:e00091. doi:https://doi.org/10.1016/j.bprint.2020.e00091
- Papaioannou TG, Manolesou D, Dimakakos E, Tsoucalas G, Vavuranakis M, Tousoulis D. 3D Bioprinting Methods and Techniques: Applications on Artificial Blood Vessel Fabrication. Acta Cardiol Sin. 2019;35(3):284-289. doi:10.6515/ACS.201905_35(3).20181115A
- Wyss Institute, 3D Bioprinting of Living tissue. (n.d.). Retrieved from: https://wyss.harvard.edu/technology/3d-bioprinting/
- Zhuang P, An J, Chua CK, Tan LP. Bioprinting of 3D in vitro skeletal muscle models: A review. Mater Des. 2020;193:108794. doi:https://doi.org/10.1016/j.matdes.2020.108794