Who's Who at NASA

Dr. Bin Chen has led the development of nanomaterials and ultra-sensitive detection techniques. Her materials development work directly supports radiation-shielding efforts, artificial photosynthesis, and sustainable energy conversion and storage, including applications in fiber solar cells, piezoelectrics, and supercapacitors.

NASA Tech Briefs: How were nanomaterials used to create a radiation-shielding system?

Dr. Bin Chen: Take one familiar example of a lead used for X-Ray radiation shielding. It would be difficult to wear such an apron in the battlefield or as part of a spacesuit. We wanted something lightweight. We used a hydrogen-rich polymer material as a binding material, which is also very effective to stop neutron penetration. We also used a carbon nanotube in alignment with the polyethylene polymer. When there is a transfer from high energy to low energy, as the polymer composite is processed, heat will be generated. We processed these three-component compound composites so that the heat flowed in one direction and easily dissipated. It’s no longer like you’re wearing a plastic bag.

The custom material is very processable. You can use it as a textile material, or you can use it as a part of a structural material, for an internal habitat or a cabin inside a plastic wall. There are other applications that people are interested in on the defense side, on the battlefield, or for firefighting — any hazardous situation where you can protect yourself from radiation.

NTB: How will composite materials improve energy harvesting applications?

Dr. Chen: Composite materials could be a solution to many old bottleneck problems. For example, we created a piezoelectric polymer device to harvest mechanical energy. In the past, [researchers] used a thin layer of metal electrode – gold or silver, for example – to minimize the cracks in thin metal films as electrodes. Our device electrode can bend and flap, and doesn’t crack or change conductivity. We found a material made with the optimal percentage of carbon nanotube and graphene. The composite electrode has very high conductivity and high mechanical compliance.

The energy harvesting can be used in a lot of embedded devices like wearable electronics. You can integrate the technology with an exercise machine where you have mechanical energy. And, of course, the material can be placed into wind turbines as an energy storage device.

NTB: What are you working on now?

Dr. Chen: We are working on an artificial photosynthesis project. We use nanomaterials to try to convert the CO2 into useful hydrocarbons and oxygen. We don’t just use a photocatalyst or an electrocatalyst. We use a composite material. You can’t plant trees in space or inside the cabin of space, and a tree only works very effectively for one season. We want to keep the tree green all year and maximize the conversion efficiency.

NTB: What is most exciting about your work with nanomaterials?

Dr. Chen: There is a limit to how far any engineering field you can actually do if you don’t understand the material. You can’t just design the circuitry and push a button; you need to invent new materials for the circuitry and device needs. People in the lab come from backgrounds like chemistry, physics, and mechanical/chemical/electrical engineering. You need all of those people to work together. That’s the exciting part. It’s a multidisciplinary area. You need to talk to a lot of different people, and you need to come up with out-of-the-box ideas and solutions.

To learn more, read a full transcript, or listen to a downloadable podcast, visit www.techbriefs.com/podcast.

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