“The printing press changed the world; three-dimensional printing could do the same”
3D printing technologies or additive manufacturing is the construction of three-dimensional objects from a digital 3D model. 3D printing refers to a group of processes that involve layer by layer material deposition to fabricate desired parts. 3D printing is transforming the design and manufacturing approaches and offers a breakthrough performance by providing unparalleled flexibility. The most common 3D printing includes stereo-lithography, fused deposition modelling and selective laser sintering.
3D printing evolved as a rapid prototyping technique. Initially, the 3D printed objects were polymeric prototypes meant to visualise end products. Today, 3D printers handle materials ranging from steels to human tissue. In addition, the ‘printing’ capability has been extended from human body parts to rocket engines. The developments in 3D printing have made it possible to build larger components with greater precision at higher speeds and lower costs. The technology is ready to emerge from its niche status and finding an ever-increasing number of applications.
3D printing promises reduced development time and tooling costs. It has the potential to create complex shapes and structures that are either not feasible using conventional technologies or are time-consuming. 3D printing could, therefore, help companies improve the productivity of materials by eliminating the wastes that accrue in traditional manufacturing. 3D printing is a new paradigm leading to profound changes in product development and supply chain.
3D printing has the capability of producing complex parts with internal structures. The manufacturing of products with such features using an alternative manufacturing process is either impossible or requires intensive tooling. This inflates the cost of the product by an order of magnitude. This technique, therefore, improves productivity. 3D printing has already reduced the product prototyping times from days or weeks to hours.
The advances in printer resolution, expansion in the range of prototype materials and elimination of secondary tooling now let companies quickly test multiple designs to determine customer choice. Apart from being a prototyping technique, the decreasing costs and increasing capabilities of the technique are making 3D printing a fast emerging direct manufacturing technique.
Boeing is already making some 200 components of different types of aircraft using 3D printing. Many medical implant manufacturers are employing 3D printing for the direct manufacturing of body implants. Components with a high labour cost, complex geometry and low volumes are great candidates for direct manufacturing using 3D printing.
Since the low production volumes create an opportunity for bespoke designs for a broader range of customers, product customisation is yet another domain where 3D printing has enormous potential. The orthodontic braces and skeletal implants are other examples of the potential of this technology. New businesses are already coming up to offer highly customised products. The fusion of 3D technologies and mass customisation will prove very disruptive in many manufacturing industries.
3D printing promises reduced development time and tooling costs. It has the potential to create complex shapes and structures that are either not feasible using conventional technologies or are time-consuming.
Another area of low production volume is replacement parts, especially in remote areas. 3D printers can transform the supply chain of spare parts by substituting large regional warehouses. Local fabrication can lead to distributed manufacturing (i.e., products being manufactured closer to customers) and therefore require a different supply chain system. Such local fabrication can also be outsourced. An example in this regard is the launching of 3D printers to the space station. 3D printers working in space are paving the way to new logistics systems for long-duration missions. Several functional items have been fabricated in space, including an antenna part and an adaptor to hold a probe on the station’s oxygen generation system. Apparently, direct manufacturing and local fabrication are the most impactful aspects of 3D printing for entrepreneurs.
Bio-printing or organ printing is an extension of 3D printing and employs similar principles to print tissue-like structures that can be put together to form vascularised organs. The field of organ printing aiming at the printing of cells, tissues, and scaffolds to create organs flowed from industrial rapid prototyping and stereo-lithography and has emerged as the most innovative solution to organ shortage and transplantation.
Organ printing uses a polymeric scaffold that acts as the skeleton for the organ that is being printed. The scaffold is impregnated with human cells from the patient’s organ that is being printed for. It is followed by a suitable incubation period, during which cell growth occurs on the printed organ. The printed organ is then implanted into the patient.
The concept of bio-printing was first successfully demonstrated in 1999 when the first artificial organ (human bladder) was printed using cyto-scribing technology. This was followed by printing a miniature fully functional kidney (2002). The emergence of new techniques (e.g., inkjet printing for cells, new bio-printers) kicked off extensive research into bio-printing and suitable biomaterials. Further research in organ printing includes liver, heart valves and tissues. Scientists in Poland have printed a functioning prototype of the pancreas. A recent breakthrough in this area is the printing of rabbit-sized hearts by Israeli researchers. The structure and functions of the printed heart are comparable to real ones. These breakthroughs point to the possibility of printing fully functioning human organs. This is a growing field in which research is still being conducted.
Like traditional body implants, successful organ printing implies full integration of printed organs into the host body. The materials used for bio-printing must be biocompatible (i.e., wield the expected beneficial tissue response and clinically relevant performance). The scaffolding materials, in addition, need to be biodegradable.
The materials used in organ production are termed ‘bio-ink’. Various natural, synthetic hybrid polymers are used as bio-ink. The selection of the material depends on the desired service conditions, printability and in vivo tissue compatibility. As 3D printed organs involve patient’s own cells, it significantly reduces the risk of transplant rejection and eliminates the use for immunosuppressive drugs.
Due to the increased number of vital organ failures, the demand for organ transplantation has rapidly increased. The supply of adequate organs has not kept pace with the demand. Consequently, we are facing major organ shortage crises. Depending upon the type of organ, waiting time can range from days to years and many people die waiting for donors. 3D organ printing has the potential to alleviate the organ shortage crisis. Furthermore, printing organs with a patient’s cells might entirely eliminate compatibility-related issues.
More research and development is still needed in various domains to enable the widespread use of 3D printing. Contrary to design for manufacturing, design for printing is still in the embryonic phase. Certain metals, slurries and gels are extremely difficult to work with. A combination of theory and experience will enable the optimisation of processes for the production of high-performance products. The areas requiring additional research and development include the stability of printed products under different modes of mechanical stresses and different environmental conditions during service.
Transport of nutrients, oxygen, and waste blood vessels requires an effective vasculature. Designing an entangled network of very small diameter capillaries in a complex geometry of organs is a very challenging task. Long-term viability and biocompatibility are some of the other challenges. In addition to the challenges of 3D printing, the unique challenges in bio-printing include cell viability, cell density, bio-printability, long-term functionality of bio-inks, a-septicity and affordability of the bio-printers.
New worlds (disruptions) are created from the fusion of creative ideas. We are witnessing layer-by-layer printing of a new colorful word that can be more captivating than our imagination.
The writer teaches at SZABIST, Islamabd, and can be reached at [email protected]