Newborn Kiaba sat still in a tiny hospital bed in Michigan wearing a little monkey t-shirt. Kiaba was suffering from tracheobronchomalacia, a condition where the primary airway in his throat couldn’t fully open. Without immediate intensive therapies, most children with this birth condition die. While he lay with tubes and wires weaving in and around him, two medical scientists, Scott Hollister and Glenn Green, found a new solution. After some CT scanning, a splint was designed in a computer program, using the exact dimensions of Kiaba’s throat. The split, a small cylinder that resembles a thimble, was created using 3D printing technology. While time was running out, Drs. Hollister and Green were able to surgically implant it, freeing his young airways. Shortly thereafter, they two were able to save the lives of two other infants suffering from the same condition. After several years, the splint was able to react to Kaiba’s natural growth and throat tissues, dissolving without a trace.
Hollister and Green were able to accomplish this daunting task thanks to the recent advancements of 3D printing. That was six years ago. The technology has grown to heights never before imagined since then. The image that comes to some people’s minds when considering 3D printing is usually a large clunky machine slowly creating a plastic mold of something silly, like a miniature replica of your favorite cartoon character. However, it’s much more complex than that. Recent leaps forward have allowed for breakthroughs in fields like medicine, but it doesn’t stop there. 3D printing has created more ways for manufacturing to become more efficient and sustainable. It’s very possible that 3D printing can change our lives in the ways that we travel, build infrastructure, utilize energy, even how we dress. These innovations aren’t just contained to Michigan with Hollister and Green; they are happening all over where people gather to learn and innovate.
Dr. Amrita Basak is one of these innovators. She’s a professor at Penn State University who specializes in manufacturing and 3D printed materials. However, she claims that she “doesn’t really have an area of expertise” and is instead mostly interested in “general ‘why’s and ‘how’s.” Although that’s selling her credentials short. She was born and raised in Arunachal Pradesh, India’s easternmost state, with her father on a farm where she spent her childhood wandering around, looking for things to fix. After going to school for chemical and mechanical engineering, she went to graduate school in the United States and worked for General Electric for six years, where she continued to fix things (except, well, professionally). Today, she’s one of very few women of color teaching engineering and actively working in the field at Penn State. The best part of working as faculty at Penn State though? “I can just start projects and nobody’s really telling me what to do,” she says with a wide cheeky grin.
She’s most enthusiastic about additive manufacturing. “Additive manufacturing is sort of a hot topic these days. It allows you to build a complex part in your computer. Suppose I want to build a prototype of you, I scan you and fit it to the computer. Then the computer does some splices and then creates an exact replica of you.” Additive manufacturing, or digital manufacturing, is the industry term for 3D printing, particularly when it has to do with special metals and different materials constructed in layers.
For those of you unfamiliar with how 3D printing works, the process is actually quite simple on the surface. Basically, a team of scientists and engineers will create a digital blueprint using Computer Aided Design (or CAD) software. This software functions as 3D imaging software, like something from an Iron Man film. Then, when the design is complete, it’s sent to humungous additive manufacturing machine that looks like an industrial oven. The design is broken down into small “slices,” which it will replicate one layer at a time. The machine will lay a super thin coating of metal down, almost like dust. And this where things get crazy: a precision-focused laser will melt the first slice of the design. It repeats the last two steps ad nauseam until each slice has created the full physical design in the correct order. Sounds simple enough, right? Think of it as making a towering club sandwich. Each layer is stacked on top of the last to create the perfect combination of the material in the right order: Bread, turkey, bacon, lettuce, tomato, mayo, and bread again! Both are a precise science. Just like experimenting with different kinds of sandwiches, engineers are limited only by their creativity. This process allows them to create structures that are highly specific and custom purposes.
Using this technology, engineers like Dr. Basak are able to do any number of things. Engineers in Ann Arbor, for instance, were able to recreate a titanium rib cage for a cancer patient after some damaging surgery. Because the software allows for such precision, they were able to create the metal ribcage and sternum to perfectly fit what remained in his chest. A permanent variation on little Kiaba’s procedure. This kind of revolutionary form of implant is extraordinarily new.
“Implants would usually come in a set number of shapes and sizes,” Dr. Basak says. “You go to the market and find an elbow and just wear it. But all of our bodies are different. Imagine putting a part in a body where there’s an obvious mismatch.”
This seemingly archaic way of creating implants is because of the two primary modes of conventional manufacturing. One is “mold-based.” This method required the construction of a rigid frame that is hollow only in the places that would form your desired part. You pour liquid metal or another raw material inside and once it cools, you break the mold and voila! There’s your part. The other method is called “subtractive manufacturing,” which is similar to the additive method. Basically, you take a huge clump of raw material and you just cut off the smaller pieces, often done with a laser, until you have the part that you want. This process is similar to creating a sculpture, you must chip away pieces from marble until you get the exact final product. While that process works when flexing one’s creative muscles, it can be time-consuming. It isn’t good for business. In many circumstances, these methods are rendered impractical and extremely wasteful. Every time you want to make a new product or a variation on an existing product, it requires an entirely new mold which will itself break down over time.
“If you use traditional manufacturing to make a mold for a specific patient,” Dr. Basak says. “By the time it’s done, they will be dead. It takes that long. Using additive, they just scan you and then it takes about seven or eight hours to get a part, like a perfectly fitted rib cage.”
However, she emphasized that additive manufacturing will not replace these methods, at least not anytime soon. We have been using these strategies for hundreds of years when it comes to making parts. When it comes to large production projects, like designing aircrafts and their engines, traditional methods are important but 3D printing methods are helping to change the industry, slowly but surely. For instance, she describes how General Electric’s Leap Engine (used in commercial jets) utilizes additives for their fuel nozzles; this has saved them millions of dollars, and untold amounts of wasted materials.
Planes have come a long way from the Wright Brothers’ days. Long gone are the flimsy wings and sputtering propellers. That process didn’t happen in a day, in fact it took decades for humans to harness the true power of flight. The massive jets that we use today require tremendous amounts of energy to build and fly. This can come at a huge cost. According to some research, if the aviation sector were its own country, it would break into the top ten CO2-emitting nations. We depend on fossil fuels to enable man to soar through the sky. As each new innovation occurred, the main focus became fuel efficiency because of its gigantic cost and impact on the environment. Until more environmentally friendly aircrafts are created, we need to innovate on a smaller scale in this vein. This is where Dr. Basak comes in.
Working with turbines and engines is one of Dr. Basak’s primary objectives. According to her, fuel efficiency is directly proportional to how much heat the engine can take. If they can be made of superalloys containing metals like treated nickel and iron, they can withstand insane amounts of heat. Keep increasing the temperature and the fuel efficiency will proportionally follow, which can be a problem because the fuel burns are about 3000 degrees. These superalloys can be created with additive methods and can operate at about 90% of their melting point, far beyond another kind of material like steel. This answers the burning question, “how is the plane I’m on not melting right now?”
This high level of energy burning can cause significant damage to the environment and the aircraft itself. “Wear and tear” is putting it lightly. The turbine blades, even when manufactured using efficient superalloys are prone to wearing down; they last about seven years and are usually thrown out with yesterday’s newspaper and empty pizza boxes. But just like those things, couldn’t airplane turbines be recycled too?
In fact, Dr. Basak worked to address this as part of Penn State’s “Project Drawdown.” The project sees students and academics from across the world join forces to work toward solutions to curb climate change and “drawdown” greenhouse gas emissions. Drawdown tackles projects in all kinds of fields, but Basak and one of her students sought to change what we do with turbine blades. Essentially, they worked on how the blades can be repaired using 3D printing to fill in where the parts have broken or worn down. You can repair the turbine several times using this method, which is better than the wasteful conventional methods. Energy loss may be decreased by 71-87% by the year 2038 by repairing these blades.
Energy doesn’t necessarily function in one particular way when it comes to additive manufacturing. Dr. Basak, as well as other faculty who worked on Project Drawdown, are researching “smart structures” that utilize a compound called barium titanate, which is a white powdery substance that acts as an electrical insulator. In additive manufacturing, that can store energy and function as a semiconductor, meaning it only conducts electricity under certain circumstances.
Smart structures, at least in this point in time, are like the final evolution of 3D printing technology. So much so that it’s been labeled “4D printing.” Structures built using 4D technology are similar in that they’re building a physical object using additive manufacturing to create a material except it is programmable and responds independently to stimuli. But how is this possible outside of science fiction?
These smart materials consist of nanocomposites, metal alloys, and shape-memory polymers that allow for greater strength and flexibility. Researchers are able to sequence these materials on a microscopic level, putting them in such an order that they behave differently from typical metals. These constructed super-elastic materials will expand and contract to heat, get larger in water, will move in light, and will even fold up in complicated shapes like origami. They are able to sequence the metals when they’re printed, basically making them into tiny computers that can act on their own accord. But don’t worry, they don’t have free will. There won’t be a cyborg apocalypse any time soon.
“Think about a sunflower,” Dr. Basak helps to explain. “When it sees the sunlight, it opens. When the sun isn’t there, it closes. That means the flower, as a structure, has a way to interact with the sunlight. Similarly, you can make these same structures using additives. You join two different materials, one will expand and the other will be unresponsive. This will cause it to bend.”
4D Printed materials can even react chemically and change their composition depending on natural or human intervention. The fibers of the material can take the formation of a honeycomb or other geometrical patterns and can be printed in a variety of different shapes to accommodate specific needs and transformations. This happens primarily because different kinds of metal and elements react differently to different stimuli. Think about how the metals in turbine blades can withstand heat better than other materials. If engineers 4D print something, some parts of it will contain those metals and others will be sequenced with different not-as-heat-resistant materials. This will cause the structure to bend and change shape when under a certain, programmed temperature.
This kind of technology has been making breakthroughs in areas like robotics and medicine. If there needs to be some kind complex surgery on the human body, you can put a “smart” 4D printed needle inside somebody. When the needle encounters a particular stimulus like chemicals in the blood, it will react and move where it is designed to. Similar to how the splint reacted to Kaiba’s throat chemicals and naturally dissolved, it all comes down to the sequencing of materials with a full knowledge how they will react to a variety of stimuli.
There’s a limit on how these work, though, according to Dr. Basak. The material aspect is finite. Just like everything, it will break eventually. These 4D materials are fragile and will usually break after a few reactions. Like a smart surgical needle that “knows” how to bend and detect certain chemicals in the human body will only be able to do this a few times. You probably wouldn’t use the same smart structures over and over for a surgery anyways. These are great first steps though. The potential of these materials is endless, they will be able to save tons of energy that would be spent running a regular electronic.
People often think of “smart” technologies as small but mighty computers like an iPhone. What makes 4D Printing materials “smart” is that the actual substance of it is programmable. The studies looked at a satellite, constructed with smart materials, that assembled itself in space. The compact components reacted to the solar heating and transformed into a deployed state, reducing the risks of human manpower in space. Eventually, we could expect to even have clothing that will change depending on elements like perspiration or the weather outside, accommodating our uncomfortable states.
The field of 3D and 4D printing have been exploding in recent years and have provided many continuing advancements across many fields. It’s going to be crucial to implement these processes where they can possibly affect the health of our planet. While the technology behind 4D printing is confusing to the average person, this technology will soon change the way we live our daily lives and will be more accessible to us.
“Within 30 minutes or so,” Dr. Basak said. “You’re already talking about old stuff. This is really fancy stuff. We say in this industry that you’re only limited by your imagination. If you think of it, you can probably make it.”
Works Cited
Chowdhry, Amit. “How Surgeons Implanted 3D-Printed Titanium Ribs In A Cancer Patient.” Forbes, 19 Sept. 2015, www.forbes.com/sites/amitchowdhry/2015/09/19/how-surgeons-implanted-3d-printed-titanium-ribs-in-a-cancer-patient/?sh=27c734262a9b.
“How 3D Printed Devices Saved Three Babies’ Lives at Mott.” YouTube, uploaded by Michigan Medicine, 29 Apr. 2015, www.youtube.com/watch?v=s9r2gYT0aX4.
Morrison, Robert J., et al. “Mitigation of Tracheobronchomalacia with 3D-Printed Personalized Medical Devices in Pediatric Patients.” Science Translational Medicine, vol. 7, no. 285, 2015. Crossref, stm.sciencemag.org/content/7/285/285ra64.
“New Manufacturing Milestone: 30,000 Additive Fuel Nozzles.” GE Additive, General Electric 4 Oct. 2018, www.ge.com/additive/stories/new-manufacturing-milestone-30000-additive-fuel-nozzles. Accessed 15 Dec. 2020.
Park, Calvin. “Computational Modeling Single Crystal Repair Development using Directed Energy Deposition.” Penn State University, https://sites.psu.edu/climatedrawdown2020/files/formidable/6/CP-Drawdown-Poster.pdf
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“What Is Additive Manufacturing?” GE Additive, General Electric, www.ge.com/additive/additive-manufacturing. Accessed 15 Dec. 2020.
Yeap, Mika. “The Future of 3D Printing: Beyond 2020.” All3DP, 11 Jan. 2020, all3dp.com/2/future-of-3d-printing-a-glimpse-at-next-generation-making.