When one thinks of potential materials for use in 3D printing, Nutella — the hazelnut and cocoa spread that is smeared on morning toast — isn’t the first thing that springs to mind. However, for chemical engineer Andrew Finkle and chemist Charles Mire, co-founders of Structur3D Printing in Kitchener, Ont., using Nutella for 3D printing has served several purposes since the start-up was launched two years ago. Nutella, which Finkle and Mire have been using as an “ink” to demonstrate the efficacy of their 3D printing system, has endeared the company to delegates at science conventions throughout North America, where their innovations have left attendees — at times literally — with a good taste in their mouth. “It’s a great attention getter,” says Finkle.
Andrew Finkle of Structure3D Printing in Ontario stands beside a fully functioning, electric 3D printed Shelby Cobra racing car. The body and chassis were printed with materials formulated by Techmer Engineered Solutions in the United States. The company created a unique carbon fibre-based formula for 3D printing that is 200 to 500 times faster than previous systems.
Nutella, which has fickle properties of flow and thickness, has also convinced the pair that their flagship invention: the proprietary Discov3ry universal paste extruder, can be used for transferring various materials, or inks, to a 3D printer, also known as a rapid prototyping system. This, says Mire, holds great potential for achieving one of the holy grails of 3D innovation: the use of hydrogels or biopolymers to “print” human skin and, eventually, organs. “If this device can print Nutella, then this device will also work well with biopolymers for tissue engineering,” Mire says. Discov3ry’s creators have designed the apparatus to ensure sterility — important for any device that potentially will be used in a medical setting. With Discov3ry, a material goes into a fully encapsulated syringe cartridge and fresh connectors, tubing and tips can be utilized for each printing run. The removable platform on a 3D printer can also be sterilized. “The mechanics never contact the material, which means we have no contamination issues,” Mire says.
Finkle and Mire are not alone in their ambition to create 3D-printed human tissue, with two Canadian university laboratories accelerating research into this area in the past several years. One is Vancouver’s Aspect Biosystems, a spinoff of the University of British Columbia that was co-founded by electrical and computer engineering professor Konrad Walus. Using unique 3D bioprinting technology, Aspect Biosystems is creating living human tissue for use by pharmaceutical companies to test new drugs and therapies. Part of the company’s long-term vision is the printing of liver, kidney and gastrointestinal tissue, with the ultimate goal being organ transplantation.
At the University of Toronto, associate professor Axel Guenther of the Department of Mechanical and Industrial Engineering in the Institute of Biomaterials and Biomedical Engineering is also overseeing the creation of 3D human tissue. His laboratory built the PrintAlive Bioprinter, which netted his research team the 2014 James Dyson Award for Canada, a design award that recognizes university student invention. The bioprinter’s ink consists of fibroblasts and keratinocytes mixed with a hydrogel. From this material, the printer produces continuous layers of tissue that mimic the epidermal and dermal layers of human skin. Although only mouse models have been used to date, the intention is to use this innovation as wound dressings for burns in the future.
(L-R) Structur3D Printing co-founders Charles Mire and Andrew Finkle created 3D busts using their own technology and readily available materials such as silicon. Photo credit: Andrew Finkle
There is growing buzz about the future of 3D printing in the media and at science conferences. Romanticized in Star Trek, where futuristic replicators synthesized a martini or steak upon command, 3D printing symbolizes science’s next leap forward. The technology, also known as additive manufacturing (AM), isn’t new, and has been in use for nearly 30 years. The cost of the technology, however, has been prohibitive, with 3D printers running upwards of $100,000, which has meant 3D has been used almost exclusively for prototyping. What has pushed 3D innovation in the past decade is the expiration of patents for desktop 3D printers. This has “democratized access” and led to dramatically reduced costs for those in industry and academia who want to incorporate 3D printing into their laboratories, says Finkle. In turn, this has led to remarkable advances in 3D innovation and technology, especially in the aerospace and automotive industries, which increasingly are partnering with 3D printer manufacturers to test and adopt new manufacturing strategies.
The market today offers mid-level 3D desktop printers that sell for $3,000 to $4,000. These have sufficient top-notch system features to render them capable of competing with commercial 3D printers that command $20,000 to $30,000 each, Finkle says. The drop in price means that more laboratories are adding 3D printers to their inventory, thus increasing the market for supporting structures like Structur3D Printing’s Discov3ry, which allows printers to handle a variety of materials by replacing only a small part: the “ink” handling system. Their system, says Mire, pushes soft material through a tube; at the end of the tube is a plastic tapered tip. The system doesn’t use the existing metal nozzles of a 3D printer, rather, the tip end of the tubing is fastened onto the existing nozzle chassis of a 3D printer. “This allows us to utilize the mechanics of the 3D printer for building stuff with soft materials,” Mire adds.
An iPhone case being printed using silicone with the Structure3D Printing prototype. Photo credit: Andrew Finkle
One of the key benefits of Discov3ry’s universal paste extruder is that it allows lab experimentation and prototype development without investing in expensive equipment, Mire continues. “Our solution fills that gap where you can at least get testing done to see if an idea is feasible.”
Structur3D Printing has attracted government backing, including a grant from the Ontario Centres of Excellence, investment from Business Development Canada, as well as a Small Business Development grant from Communitech, a Kitchener, Ont.-based funder of new tech start-ups. Structure3D Printing was also accepted into Communitech’s HYPERDRIVE startup accelerator program. As well, Mire and Finkle turned to crowdsourcing last year with a Kickstarter campaign to fund the production of Discov3ry. More than 500 backers pledged about $125,000 — four times more than was needed — for the first Discov3ry production run. Mire says further production runs are in the works.
Three-dimensional printing uses Computer Aided Design (CAD), the software workhorse for engineers and architects, for creating templates and schematics that act as the blueprints for a 3D-printed item. One well-known 3D printing process uses a powder spreader to deposit very fine powders layer upon layer. A laser melts the powder and then a new layer is spread on the previous one. Discov3ry’s uses fused deposition modelling, or FDM. The process works by taking a thermoplastic filament to its melting point and then extruding thin layer after thin layer to create a 3D object. The value lies in its accuracy and level of detail, which is in the “hundreds of microns range,” Finkle says. “It is a logical step to explore using FDM for soft materials instead of thermoplastics,” Mire adds. “However, getting such technology to produce results that are comparable to the accuracy of thermoplastics is difficult.” This is where the pair’s materials science background has been beneficial, because understanding the rheological, or consistency and flow, properties of these soft materials is paramount to getting successful “prints.”
The potential for 3D is vast, although not without controversy. For example, in the United States, CAD is being used to manufacture a 3D printed metal gun using powdered metals and alloy materials that don’t require tooling, according to Texas-based Solid Concepts – A Stratasys Company, a leading manufacturer of 3D printers. Plans for creating plastic 3D handguns: Glocks, Rugers, Berettas as well as parts for M16s and AK-47s, among other deadly weapons, have also been available on the Internet for several years. (Even 3D silencers are being created.)
Meanwhile, the Web is rife with videos of people shooting 3D plastic armaments and 3D bullets, undeterred by the US Undetectable Firearms Act, which prohibits owning a gun that cannot be seen in a metal detector.
Other potential uses of 3D printers, however, are more positive. At the University of Victoria’s biomedical engineering program, 3D prosthetic limbs with an adaptive grasp for picking up small objects are being created at a cost of only $100 each. In the US, at the Columbia University Medical Center, researchers are on the cusp of joint regeneration. Researchers have created a 3D polymer version of a meniscus, which is the shock-absorbing cartilage in the knee, for use as a tissue scaffold for healing damaged joints. The polymer is embedded with specialized proteins that attract stem cells that will rebuild the meniscus as the polymer breaks down, according to a 2014 article in Science Translational Medicine titled “Tissue Engineering.” (So far, the meniscus implants have been tested only in sheep.)
The enormous potential for 3D printing to dramatically change the face of manufacturing is no where more evident than in the automobile industry. Car parts and even entire vehicles are being made from 3D printing. A recent example is the unveiling this past January at Detroit’s North American International Auto Show of a racing Shelby Cobra. The car, which is drivable, was printed in six weeks — requiring 24 hours of print time — at the US Department of Energy’s Oak Ridge National Laboratory (ORNL) in Tennessee. Researchers at ORNL, a leader in advanced materials research and development, used 225 kilograms of printed parts, consisting of about 20 percent carbon fibre, for the 635-kilogram vehicle.
The holy grail of 3D printing is the creation of human organs from biopolymers.
Despite such successes, researchers say that 3D printers need refinement in performance, including speed, reliability and repeatability, the ability to incorporate embedded devices like batteries and electronics, as well as the ability to use a variety of materials, and even mix materials, during the printing process. Currently, 3D printing typically uses two types of plastics: polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS). PLA is a biodegradable thermoplastic aliphatic polyester that is derived from renewable starches like sugarcane, tapioca roots or corn. ABS is a petroleum-based thermoplastic polymer that is used to make LEGO blocks. ABS is less brittle than PLA, however, if implanted in the body, it can break down to produce acrylonitrile, which is potentially carcinogenic, and thus should not be used in medical implants. Additionally, problems can arise when printing thermoplastics, such as “clogging, jamming and burning” of the material, says Finkle.
Mire and Finkle have experimented with numerous materials other than Nutella: silicone, icing sugar, wood filler, polyurethane and latex. However, these materials have limitations. Most significantly is the ease of flow through the tubing linking the ink container to the 3D printer. To tackle such problems, Mire and Finkle will be experimenting with a variety of materials, including nanomaterials, in the coming years. Mire, who completed his PhD in chemistry at Australia’s University of Wollongong, is a specialist in polymer materials that conduct electricity like metal — practical for building structures used in tissue engineering. His expertise complements Finkle’s, whose master’s degree in chemical engineering from the University of Waterloo Institute for Nanotechnology’s Mike and Ophelia Lazaridis Quantum-Nano Centre focused on nanotechnology. Finkle’s current PhD studies incorporate nanocrystals for enhancing the properties of materials, as well as to bring down the cost of thermoplastics that can be used for 3D applications in the automotive and aerospace industry.
The potential use of polymers that conduct electricity like metal is that they can be used for electrical applications where metal simply cannot be used. An implantable drug-release device is an example of one such system, says Mire. It could be made out of a dissolvable biopolymer (the structure could be 3D printed), containing a drug. Electrical stimulation via the conducting polymer would trigger metered drug release over time. Once the device has done its job, it dissolves into the body with minimal side effects.
Finkle and Mire are carefully positioning Structure3D Printing to be a front runner in the area of 3D materials by strategically differentiating it in the marketplace as “expanding beyond plastic. That’s where our research is focused: exploring the cutting edge of the materials side,” Finkle says.
The future, indeed, is bright, not only for researchers like Mire and Finkle but the 3D sector as a whole in innovation and, ultimately, commercialization. While there may be a limited number of materials used today for printing, Finkle predicts that there will be a much bigger selection of materials for 3D printing “five years from now. Our company is positioned to become one of the leaders.”