3D Printing is Coming to Our Lives!

3D printing is not a novelty, it is more than 20 years old. However, the first monograph on it has only just appeared [1]. I learned about it only recently, when this manufacturing technique made its way into chemistry [2,3]. Today, rapidly developing 3D printing offers numerous marketed applications. It will bring much more in the future and its potential huge impact on society is hard to grasp. We are at the exciting moment when the technique, earlier used mainly to build tools and prototypes, is being adopted for mass production by big companies, such as General Electric (GE), Ford, Mattel [4], and Airbus [5], and by new emerging enterprises. The URBEE 2 (Fig. 1) project, for example, of building a green car with 3D-printed body and financed by crowd-funding aims for mass production in 2015 [6]. Last year Srinivasan and Bassan stated that “3D printing will be transferred from prototyping to factories” [7]. Now this process is speeding up.

Figure 1. Project URBEE. © korecologic.com

The article “Print me a Stradivarius” with a cover picture of a printed violin was published in The Economist two years ago [8, 9]. In the article, it reads “Just as nobody could have predicted the impact of the steam engine in 1750, or the printing press in 1450, or the transistor in 1950, it is impossible to foresee the long-term impact of 3D printing. But the technology is coming, and it is likely to disrupt every field it touches. Companies, regulators, and entrepreneurs should start thinking about it now. One thing, at least, seems clear: although 3D printing will create winners and losers in the short term, in the long run it will expand the realm of industry, and imagination.” (Fig 2) Undoubtedly, it will also transform science and everyday life.

Figure 2. 3D-printed lampshade. © 3Dizingof.com (Designer: Dizingof)

Contrary to “complex structures made in expensive and complex ways that come together in even more complex ways” [10], applying 3D printing consists of consecutive depositing of layers of an appropriate material and their subsequent fusion. This approach is totally different from the traditional machining techniques, in which material is removed from the starting block to create the desired shape. 3D printing, also called additive manufacturing, is described in Wikipedia as a process of “making a three-dimensional solid object of virtually any shape from a digital model” [11].

Mary Gehl states that the 3D printing was patented in the late 1970s but no source has been given for this information [12]. The term ‘3D printing’ was coined by Professor Ely Sachs, Massachusetts Institute of Technology (MIT), Boston, USA, in 1995 when he worked on a modification of the inkjet printer [13].

The Process of 3D Printing and Its Advantages

The design, created by a computer-added design (CAD) method or obtained by 3D scanning, has to be submitted to the printer. Then, layers corresponding to slices of the 3D pattern are printed successively and the layers are fused. The orientation of slicing is one of the most important and difficult manufacturing decisions, and it cannot be computerized or automated but has to be met by engineers. The type of 3D printer and the material involved determine the thickness of the slices, typically, 0.1 mm for polymers and 30 µm for metals.

The object is built up by sequentially extruding layers of polymer, metal, or even cells from a nozzle and these are then solidified and joined together or automatically fused. After each step, the work surface is lowered by the thickness of the layer to allow for the next layer to be printed, thus avoiding warping of the material when it is welded.

What kind of ‘ink’ is applied in 3D printing?
Metallic powders, polymers, resins, sand, organic materials (e.g., cells, but also chocolate), mixtures, almost anything …

You can watch the process of 3D printing on YouTube [14].

The advantages of 3D printing are:

1. Avoiding tool-based construction costs.
2. Obtaining objects of almost any shape and complexity that are difficult or impossible to make by applying traditional methods [15]. Nozzles for novel jet engines developed by GE engineers are a good example of parts consisting of 20 pieces of an odd shape that are simply printed [16].
   
3. Creating very little waste, contrary to traditional ‘subtractive’ manufacturing techniques, in which a lot of the raw material is removed. Thus, helping to limit pollution.
4. Low cost of making a prototype of part of an object, checking its performance, refining it, and only then going into mass production. In particular, one can carry out stress analysis by studying a prototype of an airplane or car part on a computer and optimizing the shape of the part from the point of view of its functionality, independently of its complexity. This speeds up the production.
5. 3D printing machines can operate 24 hours a day 7 days a week, which is difficult for man-operated equipment.
6. 3D printing can be less expensive, faster, and more flexible for small-scale production. However, the large-scale manufacture of polymer products by using traditional techniques, such as injection molding, can today be preferable over 3D printing. This may change with the rapid decrease in the cost of 3D printing.

The domain of 3D printing is a hot area to work in. It involves not only desktop 3D home printers at affordable prizes but also much larger industrial machines, novel materials suitable for printing and the adaptation of the technique for novel applications, for instance, in chemistry and medicine. Wikipedia states [11] that the efforts are driven by do-it-yourself (DIY) fans, early adopters (trendsetters), academics, and even hacker communities.

Open-Source Software and Hardware and Self-Replicating 3D Printers

We are all accustomed to free open-source software (FOSS). What about free open-source hardware [17,18]?  With an advent of inexpensive 3D printers (today costs start from $1000) [19], the machines operating with microcontrollers, such as Arduino [20] and Raspberry [21], running on FOSS, one can create custom made scientific equipment, opening up new perspectives, difficult to imagine today. You can buy a free open-source 3D printer provided by the RepRap initiative [22] and produce another one for your friend. Most of the parts of the printer are made of plastic, thus it means that RepRap self-replicates to produce a kit of itself, which has to be assembled. Of course, the term self-replication here has a different meaning from that in supramolecular chemistry where the assembly is carried out spontaneously by the objects. In any case, RepRap [22] supports proliferation of 3D printers, and thus their many applications. Another possibility is to get the plans of a 3D printer from the internet [23]. The possibilities seem to have no limits. They are, not all of them positive, discussed in an article with the provocative title “How 3-D Printing Could Disrupt the Economy of the Future” [15].

A Flood of Applications

At the turn of the century, engineers and designers started to use 3D printing intensively to quickly and cheaply build tools and prototypes, which at present are widely used in various industries. As mentioned before, today, URBEE 2, the protype of a green car with a printed body, is nearing production [6, 24], and GE are preparing to produce complicated parts for the next generation of jet engines [16]. Also, the applications of 3D printing are being extended to include industrial design, engineering, architecture, dental and medical industries, jewelry manufacturing, education, and many other domains, not only for prototype building but also for medium-scale production. As mentioned at the beginning, big companies have started programs to include 3D printing in mass production. And recently, at the Museum of Contemporary Art, Krakow, Poland, at the exposition of Polish–British Sustainable Design I saw a 3D-printed bike. On the Internet you can find, among others, a printed motorcycle [25], jewelry [26], a bikini [27], and part of a Nike football shoe [28].

Probably, 3D printing has found its most impressive applications in the area of regenerative medicine [29]. Prosthetic implants of teeth or bones [30–32] printed to exactly fit the patient are in use today. An 83-year-old patient with a badly infected lower jaw obtained a printed implant precisely to fit her needs [32]. Artificial arm prostheses are known to be expensive. However, Easton LaChappelle, a 17-year-old high school student, created a 3D-printed robotic prosthetic arm with the movement of the arm controlled by brainwaves; it costs only $250 [33]. This device, inspired by the desire to help the needy, attracted the attention of the Dutch beer-producer Heineken. Its managers wanted 500 arms for serving drinks at their bars [34].

Another example is an artificial ear created by using 3D printing by Cornell University researchers and physicians by applying injectable gels made of living cells, collagen derived from rat tails and cartilage cells from the ears of cows [35]. The collagen served as a scaffold upon which cartilage grew. After passing safety and efficacy checks, the procedure may be applied in three years to help children born with a congenital deformity called microtia and those who have lost part or all of their external ear from cancer or in an accident.

This exciting development seems to open a new era of bioprinters, also called organ printers or computer-aided tissue engineering devices, that will be able to print human organs and, thus, bring a reduction or even elimination of the need for donors. Even with today’s poor capabilities one can model a human heart to create medical instruments fit to the patient needs [36].

New exciting applications of 3D printing in prosthetics appear almost daily. Recently, a cancer survivor got a new face, some parts of which had been printed [37]. 3D printing of artificial liver tissue from stem cells has been reported [38]. Viable implants of blood vessels are more difficult to achieve [39, 40].

3D printing can also help with drug design [41]. Anthony Atala, Wake Forest Institute for Regenerative Medicine, Winston-Salem, USA, is a leading specialist in bioprinting, which involves printing cell layers along with an artificial scaffolding. His method allows him to obtain miniature and simpler versions of human organs that can be placed on a microchip and supplied with a blood substitute. They can be used to mimic the reactions of humans not only to new drugs but also to chemical warfare agents, such as sarin gas, and dangerous diseases. In such a way, animal testing or the simpler testing carried out on human cells in petri dishes could be avoided. The group of experts from various medical and chemical institutions led by A. Atala just received a $24 million grant from the U.S. Department of Defense for the study [41].

Artificial Systems to Model Cell Communication

Recently, Gabriel Villar, University of Oxford, UK, and collaborators reported obtaining 3D-printed tissues that enable them to create artificial systems that model communication among cells [42]. The system consists of tens of thousands of picoliter-sized aqueous droplets joined by a single lipid bilayer, thus forming a compact material with cooperating compartments. By using printed heterologous droplets and functionalization with membrane proteins, a specific communication path can be created. According to the authors, such networks may find various applications. They “might be interfaced with tissues, used as tissue engineering substrates, or developed as mimics of living tissue”, thus overcoming the serious limitation of synthetic models of cells that lack the possibility of cooperation.

The design may also involve the fourth dimension – time – as after the printing, the droplet networks can be programmed to fold into a variety of designed shapes. Changing the object after it has been printed, thus involving time as a coordinate, is the essence of 4D printing, which is discussed below [43]. In the work by Gabriel Villar and colleagues, University of Oxford, UK, a network, built of two strips of droplets with different salt concentrations connected along their lengths, folded spontaneously over three hours to a network in the shape of a flower with four petals [42]. Furthermore, it folded spontaneously into a hollow sphere or into another shape.

3D printing might also be used to arrange living cells within biomaterial structures, natural or synthetic ones, providing the possibility of new research [44].

3D-Printed Reactionware for Chemical Syntheses

Chemistry is another example of a field in which 3D printing is used. Lee Cronin, University of Glasgow, UK, and collaborators developed integrated reactionware for chemical synthesis and analysis by using 3D printing [2]. The scheme in Fig. 3 illustrates this process. One has to choose the reaction, design the suitable reactor, print it, perform the reaction, and monitor it in situ by using printed-in components for spectroscopic and electrochemical analysis. Then one can eventually modify the design, reagents (organic and inorganic), and catalysts to optimize the product.

Figure 3. Scheme of Cronin’s reactionware.

The group obtained the previously unreported organic heterocyclic compound C₂₁H₁₇BrN₂O [2]. They also synthesized and crystallized two new inorganic nanoclusters of the formulae (C₂H₈N)_mNa_n[W₁₉M₂O₆₁Cl(SeO₃)₂(H₂O) 2]Cl₂.xH₂O (where M = Co^II (2) or Mn^II) [2]. Interestingly and more importantly, Cronin’s group showed that the product of the reaction of 4-methoxyaniline with 5-(2-bromoethyl)phenanthridinium bromide could be strongly influenced by altering the shape of the reactor (Fig. 4) [2]; keeping all other reaction conditions unchanged, they either obtained approximately 80 % yield of C₂₂H₂0N₂O (1) or 90 % yield of C₂₂H₁₉BrN₂O (2).

Figure 4. Scheme showing the reactions performed in 3D printed reactionware. The outcome of this reaction depends of the architecture of the printed reaction vessels.

As Lee Cronin’s group puts it, “this approach constitutes a cheap, automated, and reconfigurable chemical discovery platform that makes techniques from chemical engineering accessible to typical synthetic laboratories”.

Interestingly, Cronin’s group aims also to print drugs, and is at present experimenting with ibuprofen. The results are, of course, of interest to various groups, such as pharmaceutical companies or NATO generals attracted by the idea of a portable medicine cabinet on the battlefield [3]. Cronin strongly underestimates the potential legal, medical, and practical problems his research can cause: “I don’t imagine gangsters printing their own drugs, no.” Gangsters would certainly be interested in it. But there may also arise other concerns, such as counterfeit or falsified medicines, drugs of abuse, recreational drugs, illegal narcotics, etc., as well as simple misuse of regular medicines without any control. We believe that the action of the Cronin group in domain of drugs is naïve, if not irresponsible. (Editor’s Comment: In a comment Lee Cronin discusses this opinion)

Further experimenting with 3D printing, the Cronin group created in just a few hours a number of reliable and robust miniaturized fluidic reactors for chemical syntheses for organic and materials processes by using inexpensive materials [45]. The devices were checked by performing reductive amination and alkylation reactions, large polyoxometalate synthesis, and gold nanoparticle syntheses.

What’s New in 3D Printing?

As mentioned in the very beginning, the applications of 3D printing are rapidly changing from making tools and prototypes to large-scale manufacturing. Big companies, such as GE, Ford, Mattel [4], and Airbus [5], and new emerging enterprises like korecologic [6] are driving forces for this development. At present, “odds are that, without knowing this, you flew on an airliner that included 3D-printed components, making it lighter and more fuel efficient” [7]. In the near future, huge 3D printers will be extensively used in industry [4, 5]. More and more complicated implants and prostheses will be developed and the prospects are that “taken to the extreme, 3D printing could one day enable custom medicines and reduce if not eliminate the organ-donor shortage” [7]. Of course, 3D printers will foster customization. The example of personalized iPhone cases [46] illustrates how producing to exact demands provides a competitive advantage to innovative companies. Out of many other manifestations of the customization trend, personalized medical applications, such as the printed brain-powered prosthetic arm [33, 34] modeled for a specific patient and the partly 3D-printed face prosthesis [36] should be mentioned.

Due to the rapidly decreasing cost and improved design of software or increasing range of printable materials, the development of 3D printing will speed up. Professional and amateur designers will have more access to printers, thus enriching their capabilities. They will be able to 3D print an object early in the design phase, modify it, re-print it, and so on. Thus, innovations will come faster.

3D print shops can be expected to open everywhere [7]. At present, printers are slowly being introduced into schools [47] and they will soon become common at middle and high schools in the UK and Finland [48, 49]. Kids will love them and use them for their projects.

Combining new materials, nanoscale, and printed electronics, new products having novel, previously unimaginable properties will inspire new projects and kindle creativity [7]. On the other hand, the ease in which objects can be copied will inflame heated debates on intellectual property rights analogous to those started by file-sharing sites, such as FilesTube and Shared, which enable copying and sharing music.

4D Printing

In 4D printing [43], time is used as the fourth dimension in comparison to the more conventional 3D technique. Skylar Tibbits from Massachusetts Institute of Technology’s (MIT) Self-assembly Lab, USA, announced the technique at the 2013 TED Conference in Los Angeles, USA [10]. As mentioned earlier, in 4D printing the printed object (or objects being printed) self-assembles. This requires time but creates new capabilities. For instance, objects in hard to reach places, such as underground water pipes, can expand or shrink depending on the water flow, thus avoiding the need to dig to exchange pipes. Other proposed applications of 4D printing are building self-assembling furniture, vehicles, or even buildings. By using a specialized 3D printer Stratasys [50] produced a multilayered fabric consisting of strands of a standard plastic separated by layers of a “smart” material. The latter was capable of absorbing water and exothermically interacting with it, thus allowing the material to expand after being printed. Afterwards, the rigidified material formed a structure that can be bent or twisted by the other layer.

Certainly, 4D printed objects will find applications in fixing damages in places that are difficult to reach or dangerous, such as a leaking part in a nuclear power plant, a leaking pipe laying on the sea bed, or a damaged part on a space station. On the other hand, I do not see why 4D printing must be involved for making furniture [51]. In any case, the possibilities seem exciting. This new idea allows one to experiment with materials, energy sources, design, and applications.

Pot-Pourri of Ideas

Creativity has no limits. If you would like to have a 3D-printed copy of your unborn child, the Japanese company Fasotec will do it for you [52]. A 3D-printed building that mimics the Mőbius strip is planned [53]. Raw meat will be produced by the US start-up Modern Meadow using bio-ink containing various types of cells printed into molds of agarose gel [54]. The company is supported by one of Silicon Valley’s most prominent venture capitalists, Peter Thiel, Paypal cofounder and an early investor in Facebook.

Outlook for the Future

The impact of 3D printing on technology and everyday life will be immense. In the previously mentioned article in The Economist, the future consequences of 3D printing were compared to those of the steam engine, the printing press, and the transistor [8]. According to Mary Gehl [12], 3D printing will expand enormously, reaching $3.1 milliard by 2016 and $5.2 milliard by 2020. With the costs of 3D printers falling, we will witness not only the expansion in industry but also “the explosion of 3D printing from the workplace into the home”. Terry Wohlers, of Wohlers Associates, Fort Collins, USA, states that more accessible technology will probably first attract such varied players as students, researchers, DIY enthusiasts, hobbyists, inventors, and entrepreneurs [55]. They will become a massive driving force of the rapid development of 3D printing.

As discussed by Mary Gehl in “The Implications of 3D Printing” [12], “The remarkable possibility of widespread domestic use of this technology has tremendous potential to change the way in which goods are obtained, designed, and innovated.” The accompanying changes will not be limited to the economy. The legal, and sociological implications might be similar, but much deeper, as those brought by digital formats to the music industry. The possibility to easily copy objects may infringe all key areas of Intellectual Property Law, such as copyright, design protection, patents, and trademarks.

Profound social changes are to be expected. In the first half of the 20th century, a society of consumers was created in the advanced economies characterized by large-scale consumerism and mass production of standardized products, goods that could be bought by workers who became consumers themselves. For example, they could buy Henry Ford’s black car [56]. Today’s society has changed, “small-batch production, economies of scope, specialized products, new information technologies, reliance on service jobs, and an emphasis on types of consumers rather than on social class” are typical. This may be changed in the future with 3D printers making our economy much more flexible, altering many of our contemporary social and economic relationships on a global basis. The society would shift from a world of passive buyers to one where production and consumption are continuous and symbiotic. Consumerism would change to prosumerism where production and using objects could be mixed, for instance, when you produce parts to fix your appliances at home or make yourself a necklace. Both the prospects of 3D printing and the social change are hard to estimate.

The Latest Developments

The domain of 3D printers is expanding rapidly, something new and exciting emerges almost every day. Even faster development and spread of 3D printers is expected because many patents in this area have already or will soon expire and this will lead to new investment, innovation, and competition [57]. Novel printing materials include carbon fiber [58] and fiberglass [59]. Being Polish, I was happy to learn that a Polish start-up, which raised funds at Kickstarter, produces very reliable 3D printers that operate with custom software and cost under $2000. The company, Zortrax, signed a contract with Dell for the delivery of 5000 of these printers [60]. Two kitchen-ready 3D food printers, the ChefJet and ChefJet Pro, were presented at CES Trade Show by the South-Carolina-based company 3D Systems, which advertises itself as “the world’s first and only professionally-certified, kitchen-ready 3D food printers” [61]. The ChefJet can print sugar, chocolate, and candy in any imaginable design. The larger printer, ChefJet Pro, is additionally stuffed with a full palette of food colorings and dyes, which enable incredibly elaborate treats to be printed.

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