Infinitely Flexible 3D Printing with … Ultrasonic Manipulation?
Michael Molitch-Hou posted on July 11, 2017 | 6534 views

3D printing is an exciting technology in its own right, but, as it works today, it is normally used to fabricate individual components and not functional objects. At most, hundreds of parts in an assembly can be consolidated into a single 3D-printed item, but that item still cannot function on its own.

Progress is being made to change additive manufacturing (AM) technology into something even more powerful, however. In the future, it may be possible to fabricate complete functional objects in a single manufacturing process. Think of it: your smartphone could be produced in one piece in one automatic process.

One company has demonstrated a possible route to that ideal future. Using a unique ultrasonic technique, Neurotechnology, based out of Lithuania, may be able to 3D print a wide variety of objects, including circuits. ENGINEERING.com spoke to Osvaldas Putkis, research engineer and project lead for the company’s Ultrasound Research Group, to learn more. 

From Biometrics to Ultrasonic Manipulation

Neurotechnology is focused on developing algorithms and software for biometric applications, such as fingerprint, face, eye and voice recognition. Since launching its first fingerprint identification system in 1991, Neurotechnology has begun exploring other technologies, beginning research into artificial intelligence (AI), computer vision and autonomous robotics in 2004.

“While Neurotechnology’s core business is in the fields of biometry, computer vision and AI, it is always looking for opportunities to research and develop new technologies that sometimes can be outside the main company’s focus,” Putkis said. “Ultrasonic manipulation seemed an exciting research area with an unused potential and, with the hiring of key personnel who have expertise in ultrasound, an Ultrasound Research Group was created three years ago.” 

Ultrasonic manipulation? No, it’s not a sleazy method for picking up strangers at a bar from the dirt bags that brought you those pickup artist guides. It involves using ultrasonic waves to grab and move objects. 

A rendering of Neurotechnology’s ultrasonic manipulation technique. (Image courtesy of Neurotechnology/YouTube.)
A rendering of Neurotechnology’s ultrasonic manipulation technique. (Image courtesy of Neurotechnology/YouTube.)

Typically, according to Putkis, most of the research and development in ultrasonic manipulation has been dedicated to liquid media for “for cell sorting, cell patterning, [and] single cell manipulation.” Applied research on manipulation in air, Putkis said, “concentrates on container-less processing and analysis of chemical substances by levitating the samples.”

Ultrasonic Manipulation for 3D Printing

After establishing the Ultrasound Research Group in 2014, the company developed a working prototype, finally releasing footage of its ultrasonic manipulation technique this past June. The process uses a computer with computer vision and an array of ultrasonic transducers, each of which can be controlled individually to grab, move and rotate components by changing the ultrasonic waves they emit. 

In the demonstration video embedded above, the system has been set up to position and solder electronic components on a printed circuit board (PCB). Soldering is performed using an onboard laser that fuses the pieces onto the PCB, and is guided by the vision system. Altogether, there is no physical contact made with the objects being moved and soldered, opening up a number of possibilities. 

Neurotechnology’s ultrasonic manipulation prototype 3D printer. (Image courtesy of Neurotechnology/YouTube.)
Neurotechnology’s ultrasonic manipulation prototype 3D printer. (Image courtesy of Neurotechnology/YouTube.)

"Ultrasonic manipulation can handle a very large range of different materials, including metals, plastics and even liquids," Putkis said. "Not only can it manipulate material particles, it can also handle components of various shapes. Other noncontact methods, like the ones based on magnetic or electrostatic forces, can't offer such versatility."

This range of material manipulation, not seen with other technologies like magnetic or electrostatic techniques, means that the technology can print with elements that have a variety of shapes and mechanical properties. This includes liquids, such as conductive ink, and solids, like electronic components. These elements can range from a couple of millimeters in size to submillimeter particles. And ultrasonic manipulation can do this without causing any damage to the elements or introducing electrostatic forces into the process. 

Ultrasonic manipulation can control a wide variety of substances, shapes and sizes. (Images courtesy of Neurotechnology/YouTube.)
Ultrasonic manipulation can control a wide variety of substances, shapes and sizes. (Images courtesy of Neurotechnology/YouTube.)

By altering the ultrasonic profile of the process, the precision of object movement and placement can become highly refined. With ultrasonic waves of 40 kHz, it’s possible to attain accuracies of within tens of microns. Even higher frequencies result in even more precise movement.

Putkis explained that there may be weight restrictions with the ultrasonic transducers, but that this may not always be the case when the density of the elements is taken into consideration. “[Pa]rticle dimensions should be in a sub-wavelength region of the ultrasonic waves used,” Putkis said. “In terms of weight, it is usually the density of the material that is the determining factor. You will need to create very similar pressure amplitude in order to levitate a 1-millimeter diameter or a 2-millimeter diameter plastic sphere. While the gravity force is bigger for a larger sphere, a larger sphere also has a larger surface area, increasing pressure force respectively. With our semisphere levitator shown in the video, we can levitate materials as dense as solder metal (approx. 8000 kg/m3).”

The technology is also already fairly automated. The camera is capable of determining the PCB’s position and orientation, making it possible to know where a component should be positioned. The circuits used in the company’s demonstration are not overly complex and do not have many elements. Therefore, the trajectories can easily be calculated, according to Putkis.

“The transducers then create appropriate pressure fields and transport components to their designated locations on the PCB,” Putkis said. “However, for more complex circuits, some autorouter algorithm would need to be implemented for calculating those transportation trajectories.” 

The Next Steps for Ultrasonic Manipulation

Neurotechnology has already filed a patent for the technology and is continuing to develop its capabilities. At the moment, the system can only assemble simple electronics, so the Ultrasound Research Group intends to expand the platform.

“[O]ur plans now are to develop and demonstrate capabilities of the technology to print/deposit other materials or components,” Putkis explained. “As our main expertise is in ultrasound, we are willing to cooperate with companies from the 3D printing industry in order to incorporate the technology in 3D printing systems.”

“If we are successful in adding the capability of printing plastics and improving the current prototype for electronic assembly, it would already be a powerful printer that can print some of the electronic devices,” Putkis added. “Another application could be to use ultrasonic manipulation just for component handling and integrate it to existing printing technologies of plastics or metal, in this way also creating a more universal printer.”

To make the platform as flexible as possible, Putkis noted one specific challenge. “The biggest challenges are finding methods for dispensing and soldering material and components that can work for a wide range of different components and materials in order to make full use of the handling versatility of ultrasonic manipulation,” he said.

It would be interesting to see Neurotechnology partner with 3D printing companies already focused on electronics 3D printing. Two immediately come to mind: Voxel8 and Nano Dimension. Voxel8 has developed a fused deposition modeling desktop 3D printer that is capable of printing plastic parts with conductive silver ink traces, making it possible to manually embed electronic components to create functional objects. Nano Dimension, in contrast, relies on an inkjet printhead and photocurable resin to produce PCBs.

In both cases, electronic components must be manually inserted. It’s not impossible to imagine incorporating an array of ultrasonic transducers into either platform in order to automatically move the components throughout the printbed as the fabrication process is taking place.

Facebook also recently scooped up a company, Nascent Objects, that was using EnvisionTEC’s digital light processing technology to 3D print functional electronic goods. Although we haven’t heard from the company in some time, the acquisition is an indicator that this field is a potentially highly valuable one. We may still be years away from being able to 3D print a complete cell phone in a single printing process, but even the steps along the way will be exciting ones, as Putkis’s research shows.

To learn more about Neurotechnology, visit the company website.

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