US researchers have 3D-printed RAM components in zero gravity

Researchers at the University of Wisconsin-Madison have taken a step toward space manufacturing of replacement electronic components by successfully 3D printing RAM devices in microgravity for the first time.

The UW-Madison team achieved this milestone in March 2024 during a parabolic test flight at Fort Lauderdale-Hollywood International Airport in Florida. The NASA-funded research, led by Hantang Qin, assistant professor of industrial and systems engineering, aims to enable the manufacturing of electronic components such as semiconductors, actuators and sensors in space. This would enable repairs in space without having to transport spare parts. “A lot rides on these experiments,” says Rayne Wolf, a PhD student from Potosi, Wisc., and one of the team leads.

Traditional 3D printing relies on gravity to extrude material from a printer nozzle. Since this doesn’t work in space, Qin’s lab developed an alternative called electrohydrodynamic (EHD) printing. This technique uses electrical forces to control the flow of liquid material through an extremely thin nozzle just 30 micrometers in diameter.

“Under this small scale, the surface tension will prevent the liquid from flowing out from this nozzle,” says Qin, whose group is leading the collaboration with researchers from Iowa State University, Arizona State University, Intel and other industry partners. “And then we apply this electrical force to break out of this surface tension force.”

During the first two test flights, technical problems arose as vibrations from the aircraft engine affected the printer’s calibration sensors. The team was able to solve the problem by adapting the system’s code, as Pengyu Zhang, a PhD student in electrical and computer engineering, reported.

“But using our printing system, we can make the droplet way smaller than the size of nozzle,” he says. “Given a 2-micrometer nozzle, we can make a nanoscale pattern. That’s the huge advantage of this.”

On the final test flight, the EHD printer successfully produced over a dozen RAM units of zinc oxide, a semiconducting ink, and several units of polydimethylsiloxane, an insulating polymer ink, under the manual control of Rayne Wolf and Jacob Kocemba.

“We got a good feeling when we were in the air and the stages were working,” says Khawlah Alharbi, a PhD student who was in the air for two of the test flights. “When the results came out, we were really satisfied and happy and excited to move on with our research.”

The team plans to return to Florida in August and November 2024 for further test flights. The plan is to integrate the EHD technology into an industrial partner’s multi-purpose 3D printer to move from individual units to full-fledged semiconductor devices. The goal is to test this technology on the International Space Station (ISS). “If we can send this up to the ISS,” says PhD student Liangkui Jiang, who’s worked on the project since conception, “it would be a happy ending.”