Smart Parts Riding on the Wing of a Newly Developed Technology

Smart Parts

When an engineer sits down to design an electro-mechanical system, he might find himself scratching his head at finding a way to fit ten pounds of electrical wiring, clips, passive components, and brackets into a five pound area. But what if all those electrical components could be printed onto a part using additive manufacturing and electronics printing technology?

Stratasys and Optomec Inc. recently combined forces to create the world's first fully-printed hybrid structure--a "smart wing" for an unmanned aerial vehicle (UAV) provided by Aurora Flight Sciences that has opened doors for a slew of other parts in various industries that could be made faster, cheaper, and altogether "smarter."

For the aerospace industry, that could mean printed parts that instantly access sensitive electronic data on a future generation of airplanes, said Jeff DeGrange, who worked at Boeing for 20 years before becoming Stratasys's current VP of direct digital manufacturing. "What happens if an aircraft control system valve gets stuck? With 'smart' capability, you can sense the pressure drop that might cause a flap to malfunction. It's about being able to sense that quickly. I think that's where the technology can go to make a more robust, smart product as we head to the future," DeGrange said in a phone interview.

An Optomec Aerosol Jet system was used to print a conformal sensor, RF antenna, and circuitry directly onto the wing of a UAV model provided by Aurora Flight Sciences. The wing was 3D printed with Stratasys's patented Fused Deposition Modeling (FDM) process. The RF antenna transmits live video from a camera to a remote display monitor, and the propeller and LED are powered by circuits also printed on the wing structure with Aerosol Jet. A video on discusses the making of the hybrid structure.

"I think the smart wing project now brings forward the notion of the fully printed device--that you can print the substrate, as well as the electronics that go onto that substrate," said Ken Vartanian, director of marketing for Optomec. "I think this project is opening the eyes of industries to the potential of a fully-printed product and that's what's getting people excited. We're able to fully print not just the mechanical or plastic structure that makes up the body of the device, but also the electronics that give it the smarts. We have received an incredible amount of interest in it," he added, explaining that the technology can benefit numerous industries, including aerospace and automotive, by allowing for thinner, lighter, fully-functional structures that cost less to manufacture.

Optomec recently showcased some of its "smart structures"--including two complex mechanical structures that were functionalized using Aerosol Jet 3D printed electronics capabilities--at the IDTechEx conference held in Berlin, Germany, in May. One was the smart wing; the other featured fill-level sensor and control circuitry printed on the end of a molded plastic tank. When water is pumped into the tank, the sensors register the water level as it rises, lighting LEDs to indicate the fill level. When the tank compartment is full, the circuit senses the water fill level and reverses the pump direction.

Because numerous steps are eliminated in the manufacturing process using the additive technique, coupled with less chemical waste to deal with and a more efficient use of material through the Aerosol Jet technology, there are significant cost savings involved with the pairing of the two processes, Vartanian said. The system has also proved efficient and cost-effective for 3D printing of interconnects on semiconductor packaging, and Optomec is focused on bringing its Aerosol Jet technology to high-volume electronics industries, such as smart phones and tablets.

"Aerosol Jet technology is very scalable. We're in the process of scaling it up so we can have multiple nozzles that are depositing material simultaneously on a single device," Vartanian said. "If you look at our R&D efforts today, that's where we're devoting our efforts--to high-volume applications."

Optomec is a provider of additive manufacturing solutions for high-performance applications in electronics, solar, medical, aerospace, and defense markets. These systems utilize Optomec's patented Aerosol Jet Printed Electronics technology and LENS powder-metal fabrication technology.

Recently, an Aerosol Jet printer was used to directly attach an LED die to heat sinks, rather than the current multi-layer package architectures. The direct-attach approach offers many benefits, including reduced thermal resistance, improved heat dissipation, increased power densities, smaller form factor, and lower cost. Aerosol Jet can also be used as a replacement for conventional wire bond technology for top-side interconnects, and as an enabling solution for flip-chip configurations. Aerosol Jet printers have the unique ability to produce a wide range of electronic, structural, and biological patterns onto almost any substrate. The proprietary process, which is different from ink jet, utilizes aerodynamic focusing to deliver fluid and nanomaterial formulations that, as required, can be optionally post-treated with a highly-focused laser or other sintering methods. The resulting patterns can have features that are less than 10 microns wide, with a layer thickness from tens of nanometers to several microns. Wide nozzle print heads are also available, which enable efficient patterning of larger size features and surface coating applications.

Hybrid Technology Enhances Complex Abilities

Aurora Flight Sciences, a supplier of UAVs, provided the electrical and sensor designs for the smart wing. The key to the smart wing is that it is multifunctional, said David Kordonowy, who leads the Aurora Flight Sciences Aerostructures Research Group. "It's a wing structure that can do some complex tasks. It can route electronics or it can broadcast signals or monitor strain or the deformation of its own structure using printed electronics," he said. "When you have the ability to embed or to print conductive traces onto a structure directly, what it allows is for that structure to perform tasks beyond simply taking loads."

The combining of printed electronics with 3D printing for the wing has allowed for UAVs to be built more quickly and with more customization. The time and cost to develop complex tooling using traditional processes is no longer a factor with the additive manufacturing process. "The tooling is expensive, and the time and labor it takes to lay up and cure these parts is also expensive," Kordonowy said in a phone interview. "And what additive manufacturing offered to us was the chance to create complex geometries very quickly without having to resort to complex tooling and autoclave or oven curing of parts. We simply insert the geometry into our Fortus machine or some other type of FDM machine and it prints out a part to our specifications."

Stratasys, a Minneapolis-based maker of additive manufacturing machines for prototyping and producing plastic parts, offered up its FDM technology to the project, which enables complex shaped geometries to be produced "seamlessly," DeGrange said, adding that the material properties the machines can build with are stable and varied. "When you look at the final output of those materials, they are very durable. Many of them can withstand very high temperature environments and very cold temperature environments. They are very stable, meaning they won't change over time, and so I think the primary reasons why FDM is a great additive manufacturing technology candidate is based on material properties and stability of those properties," he said.

Bringing the two technologies together is a "game changer" for design and manufacturing, DeGrange said, explaining that "it has the potential to completely streamline production by requiring fewer materials and steps to bring a product to market." All of the wire bundles, clips, and brackets get minimized because they are printed right onto the surface of the parts. The printed electronics allows for a lighter part that also has enhanced electrical performance. The printed circuitry, DeGrange said, enhances performance in terms of response time. "Depending on how you actually route your electronics on your surfaces, you can actually put a signal at one end and it gets to the other end quicker versus a wire," he said. "You're putting more electronics in confined spots, so you get a faster response time from those electronics. And by taking out all of those wire bundles, connectors, clips and brackets, the overall vehicle will be lighter, and so what does that mean? It means if they're flying on batteries or fuel, they will be more energy efficient and can fly longer." All of these benefits will likely mean that the U.S. Department of Defense will become an early adopter of the technology, DeGrange continued.

"I think in the near term, meaning in the next one to two years, you'll see a number of Department of Defense agencies, as well as related defense contractors, start to say, 'Wow, we didn't even think about how you can use just the FDM technology and then print circuits onto it.' They will start to embrace it, buy the machines, utilize the technology, and use both the technologies to prove it out for whatever products they might have in mind," DeGrange said.

A UAV could be especially made for a specific mission, such as attack or reconnaissance, explained Optomec's Vartanian, adding that supply chain and logistics are very important for the military. He explained that the result of combining 3D printing and printed electronics also makes for a lighter part, which makes the technology especially attractive to the automotive and aerospace industries. "From a wiring standpoint, printed electronics are a much lighter weight than traditional wires with insulation on them. They're much lower mass for the printed conductor and we don't have to coat the entire wire with insulation. We just have to put a very thin coating of dielectric on top of the printed wire," he said.

Looking to the Future

Once some of the technical elements get ironed out regarding the combination of the two technologies, such as circuitry holding up in certain temperatures, it will make its way into the commercial market, he said. Some commercial markets will likely "scoop it up, run with it, and go wide stream." An example of this is with the UAVs themselves. They are currently being used in defense department applications, but there's big commercial market potential for UAVs as well, he said. "If you live in a metro area and have rush hour traffic in the morning and afternoon, you can send UAVs, rather than helicopters, to see whether there are wrecks or bottlenecks on the roads. Or if you [have] burning buildings, you can fly them over and see where the fire is," DeGrange said. He also mentioned the ability to integrate the two technologies into the making of prosthetics.

"If you think about someone who has lost a right hand, now you can use all the information from the left hand and get the right weight balance, so it feels natural and you put the electronics into that. With those electronics, you can now give voice commands; you can say 'open' and 'close' so you can drink a glass of water or cup of coffee. So I think that's what this really means when you start talking about future stages of where it (technology) can go."

Other uses for medical devices might be for pressure- and temperature-type testing. For example, DeGrange said, if a company is making a custom surgical tool for hip replacements, they would be able to generate a cutting tool that's unique to the patient's body using CT scan data. "You could then actually print the electronics onto that, you could measure what the patient's body temperature is, and you could measure how much pressure is being applied against a patient so it's (device) not being jammed up against a patient causing any kind of discomfort," he explained.

Although the technology, because of the current number of steps involved, is not suited for mass-produced electronics, such as the iPhone®, it is well-suited for high-performance industries focused on low volumes, DeGrange said. For high-performance consumer cars like Ferraris and Aston Martins, as well as for the stock-car racing industry, this type of hybrid technology could result in lighter cars that can go faster. "Those wire bundles are very heavy in cars, and they're (racing industry) always looking for ways to get weight out of cars. A lighter weight car can go faster down the track." With printed electronics and FDM-produced parts, response time would also be improved, so that the sensors on the race cars can offer faster information on such aspects of the car as oil pressure, engine temperature, and tire and brake temperature. "Being able to sense that and respond to that, even if it's half a millisecond quicker, can sometimes make a difference in how you finish the race," DeGrange said. "I think the Formula One industry will probably really see this (technology) and take a serious look at it and be early adopters as well, in order to get those performance gains. It's all about performance."

According to a recent BCC Research report, printed electronics are steadily proving that they have the potential to bring about a revolution in electronic applications. The global market for printed electronics, which was valued at nearly $3.5 billion in 2011, is expected to increase to $12.6 billion in 2016.  According to the report, the revolutionary character of printed electronics lies not only in its low cost, ease of manufacturing, and small size and weight, but also in its ability to facilitate applications that are not feasible or are uneconomical with conventional silicon-based electronics.

Aurora Flight Sciences is also working with Stratasys on building wind tunnel models in conjunction with NASA and the Massachusetts Institute of Technology (MIT), looking at advanced concepts of aircraft in the 2020-2030 time frame using additive manufacturing to develop concept configuration for a 737 class transport aircraft.  Working with Stratasys has been a "natural fit" as the two companies come up with ways to create multi-functional structures that, while pushing the edge of innovation in 3D printing, offer significant cost savings to customers and a streamlined manufacturing process, Kordonowy said. "As a UAV system provider, we really know the requirements for UAV and also have a sense for what the system could do and should do," he said. "So when technologies come out of these small companies or even big ones like Stratasys, I think it's our role to guide it in a way that could be meaningful for us and our customers."

Headquartered in Manassas, Va., Aurora Flight Sciences focuses on the development and manufacturing of advanced aerospace vehicles. Aurora operates production plants in Bridgeport, W.Va., and Columbus, Miss., and a Research and Development Center in Cambridge, Massachusetts. There is much potential for this new technology, Kordonowy said, and future applications include moving the manufacturing of UAVs and parts closer to the field so that they are immediately available on-site without having to wait for them to be made and shipped from afar. "And similarly, if you have a UAV that is damaged or needs a spare part, instead of having a huge supply chain to have parts available stockpiled and [shipped] to wherever you are, you can have one of these machines that can print out a variety of different parts and bolt those back on. And the multifunctional aspects let you print not only structure, but multi-functional (electronic) structure that can perform tasks like wiring, or electrical signal routing, and antennas," he said.

The smart wing is a good "bench test" that has allowed the  industry to see the feasibility of merging 3D printing with printed electronics, Kordonowy said, adding that the next step is to test that capability under flight conditions, including flying a UAV with the smart wing inside of a controlled simulation environment. "It's a benefit really to be able to explore these types of technologies and to brainstorm how they can be applied," he said.

Fused Deposition Modeling is a trademark, and FDM, Fortus, and Stratasys are registered trademarks of Stratasys Inc.

iPhone and iPad are registered trademarks of Apple, Inc.

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