The famous US aerospace and aeronautics agency NASA is currently developing sensors based on graphene. The main leader of the initiative, Mahmooda Sultana, joined NASA's Goddard Space Flight Center in Greenbelt two years ago. She had since then won research and development fundings to install graphene production facilities.
NASA's graphene production is based on Chemical Vapor Deposition a technique widely spread among the microelectronics industry. The same material, also known as CVD graphene, is developed in our labs at Graphenea.
Sultana's group is now manufacturing high quality graphene and is working on applications. For them, the most promising use of graphene is with chemical sensors.
Chemical sensors based on graphene
The original vision of tiny instruments for atmosphere sensing is due to Fred Herrero who has been pushing NASA's research line in that direction for over a decade now. The encounter between Sultana and Fred gave birth to the development of a miniaturized, low-mass, low-power, graphene-based detector. The aim of this device is top measure the amount of single-atom oxygen in the upper atmosphere.
Researchers already know that atomic oxygen accounts for up to 96 percent of the low Earth atmosphere that creates the atmospheric drag experienced by orbiting spacecrafts. This atmospheric drag leads to a premature loss of altitude for the satellites.
"We still don’t know the impact of atomic elements on spacecraft in creating a drag force," he said. "We don’t know how much momentum is transferred between the atom and the spacecraft. This is important because engineers need to understand the impact to estimate the lifetime of a spacecraft and how long it will take before the spacecraft reenters Earth’s atmosphere."
The solution came naturally from graphene and Sultana's expertise. Like many metals, when graphene absorbs an ato of oxygen, a change of electrical resistance occurs. The advantage of graphene is that it greatly simplifies the steps needed to measure atomic oxygen. Sultana also claims a similar chemical sensor could be used for methane, carbon monoxide or other kind of gases. However she admits that her research is still at an early stage.
An other useful graphene application for NASA would be the detection of stress in engineered composites. By embedding stress-sensitive graphene in a multi-layer composite, they can obtain smart material that could monitor internal stress.
For that purpose, NASA is collaborating with the MIT (where Sultana studied as a PhD student). They plan to produce large sheets of CVD graphene to be deployed in a non invasive way to detect damage or potential source of breakage. Replacing the relatively large instruments currently in use for strain detection with thin and light graphene-based devices would be a great step forward.
“We can employ a different combination of its extreme properties and use the same material for different sensing applications,” Sultana says. “That’s the beauty of graphene.”