MIT scientists revealed the 3D printed sensors they developed for satellites. This is also the first time that plasma sensors for orbiting spacecraft have been completely digitally manufactured. Satellites use these plasma sensors, also known as retarding potential analysers (RPAs), to determine the chemical composition and ion energy distribution of the atmosphere.
The MIT researchers discovered that 3D printed sensors and laser-cut sensors outperformed expensive, cleanroom-made semiconductor plasma sensors. Furthermore, 3D printed sensors can be made in a matter of days for tens of dollars.
The sensors are ideal for CubeSats due to their low cost and quick production. These low-cost, low-power satellites are frequently used for communication and environmental monitoring in the Earth’s upper atmosphere.
3D Printed Sensors for Satellites
RPAs were created by the researchers using a glass-ceramic material that is more durable than traditional sensor materials such as silicon and thin-film coatings. They were able to create sensors with complex shapes that can withstand the wide temperature swings that a spacecraft would encounter in lower Earth orbit by using glass-ceramic in a fabrication process developed for 3D printing with plastics.
According to Luis Fernando Velásquez-García, a principal scientist in MIT’s Microsystems Technology Laboratories (MTL) and senior author of a paper presenting the plasma sensors, “Additive manufacturing can make a big difference in the future of space hardware. Some people think that when you 3D-print something, you have to concede less performance. But we’ve shown that is not always the case. Sometimes there is nothing to trade off.”
Joining Velásquez-García on the paper are lead author and MTL postdoc Javier Izquierdo-Reyes; graduate student Zoey Bigelow; and postdoc Nicholas K. Lubinsky. The research is published in Additive Manufacturing.
Versatile Sensors
The success of an RPA depends on the housing structure that aligns the meshes. It must be electrically insulating while also being able to withstand sudden, drastic temperature swings. The researchers used Vitrolite, a printable glass-ceramic material with these properties.
The long-lasting material can also withstand temperatures of up to 800 degrees Celsius without degrading, whereas polymers used in semiconductor RPAs begin to melt at 400 degrees Celsius.
“When you make this sensor in the cleanroom, you don’t have the same degree of freedom to define materials and structures and how they interact together. What made this possible is the latest developments in additive manufacturing,”
– Velásquez-García, a principal scientist in MIT’s Microsystems Technology Laboratories (MTL)
Rethinking Fabrication
The MIT researchers used vat polymerization, a decades-old process for additive manufacturing with polymers or resins. A 3D structure is built one layer at a time using vat polymerization by repeatedly submerging it in a vat of liquid material, in this case Vitrolite. After each layer is added, ultraviolet light is used to cure the material, and the platform is submerged in the vat once more. Because each layer is only 100 microns thick (roughly the diameter of a human hair), smooth, pore-free, complex ceramic shapes can be created.
Because the sensors were inexpensive to produce and could be manufactured quickly, the team prototyped four distinct designs.
Velásquez-García added, “This high precision could enable 3D printed sensors for applications in fusion energy research or supersonic flight. The rapid prototyping process could even spur more innovation in satellite and spacecraft design.”
Velásquez-García now wants to explore the use of artificial intelligence to optimize sensor design for specific use cases, such as greatly reducing their mass while ensuring they remain structurally sound.
This work was funded, in part, by MIT, the MIT-Tecnológico de Monterrey Nanotechnology Program, the MIT Portugal Program, and the Portuguese Foundation for Science and Technology.
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