Interview with Yao Zhao

Featured Engineer

Yao Zhao

Yao Zhao - Research Assistant at Rice University

Image: Yao Zhao shows a demonstration rig in which he uses a short piece of carbon nanotube cable to provide standard line voltage to a fluorescent light bulb.

How did you get into electronics/ engineering and when did you start?

I did bachelor and master in physics. At the point that I finished the master degree, I felt that I have built fundamental knowledge and would like to apply the fundamental knowledge in applications. So I started my Ph.D. study in materials engineering at Rice in 2007. At Rice, I started to study electronic materials. When I was doing the nanotube cable project, my knowledge in physics helped me understand the conduction mechanism in the cables and kept me on the right track in optimizing the performance of the cables.

What are your favorite hardware tools that you use?

My favorite hardware is high resolution transmission electron microscopy (HRTEM). This fantastic tool enables me identify the atomic-scale signatures of electronic materials such as carbon nanotubes. Characterization of these signatures is critical for understanding electrical behaviors of materials. Particularly for carbon nanotubes, signatures at atomic scale such as defects and diameter are deterministic factors for electrical properties of tubes.

What are your favorite software tools that you use?

My favorite software varies as I work on different projects. To accomplish a task, normally more than one software can be used. Software should always improve work efficiency. I always think is there a better one can be used when some software is not very handy.

What is on your bookshelf?

I have a lot of physics books on my bookself such as quantum mechanics, classical electrodynamics etc. When I came up with a problem in research, which does not have exact answer in books, I would like to search relevant information on internet and see if it can inspire me to find solutions.

What are you currently working on?

I am working on optimizing production of the nanotube cables. Basically the whole production process can be divided into three stages, nanotube growth, processing and post-conditioning. Currently we are optimizing each stage individually. Eventually we will integrate all the individual optimized steps into an automated production process.

How did the Nanotube cables carrying electrical currents project come about?

Prior to this project, I was studying the electrical properties of the nanotube/polyethylene composite. I found that the hurdles in improving conductivity of the composite are a thin polyethylene layer wrapping around nanotubes and disconnection at tube-to-tube junctions. The finding inspired me to use pure nanotubes and optimize the intertube junctions in creating highly conductive nanotube cables.

What has been your role in this project?

This project involves with three research units. Rice is one of them. I am the researcher at Rice being in charge of processing and post-conditioning. The raw nanotube growth was mainly conducted by a research group in Tsinghua Univerisity, China.

Can you tell us about the process of making nano cables?

First, double-walled nanotubes were grown by chemical vapor deposition (CVD) technique. As grown, nanotubes were interconnected and formed a continuous network. Then, purification was conducted to remove the amorphous carbon and catalysts. Followed by the purification, the nanotubes went through a serial of processing steps, soaking, spreading and shrinking. As a result, the nanotube cables were created. Conditioning step was added at the end, in which iodine doping was applied on the cables.

Can you tell us about the success of this technology?

The iodine doped carbon nanotube cables reached a milestone; the specific conductivity (conductivity by weight) of the doped cable exceeds copper and aluminum. The strength of the cables also beat the metals. Moreover, consider the feasibility of scaling up production and lowering the cost in the near term, the iodine doped nanotube cables could be a serious contender for traditional metals and be used in energy systems of the future.

What direction do you see your business heading in the next few years?

This research will head to commercialization and manufacturing phases from the laboratory research phase in the next few years. We are confident that the technique for producing nanotube cables will become mature in next 2 to 3 years. The cost can be tuned down as the production is scaled up.

What challenges do you foresee in our industry?

I can see more electronics based on nanotechnology will come out to market in next few years.

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