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A bit more about CNT resonators...

Here I show you the image of a high-frequency CNT resonator. It's a suspended SWNT of 100nm length and 4nm diameter.




Now the explication :)
It operates in transistor geometry, as shown below. Source-drain is where the AC current flows, inducing vibrations and with changing voltage on the gate we can change nanotube mechanical tension.
And yes - the actual resonator is the ultra-short carbon nanotube! It's so tiny that it's difficult to image it in SEM. But because it's so small it's easy to achieve high frequency operation!



The details of the high frequency devices will be published in Applied Physics Letters SOON!!! But I'll also try to explain it here in an easier way!
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Carbon nanotube resonators

During this year I worked a on mechanical resonators made of carbon nanotubes.

In general we have two types of carbon nanotubes (CNTs): single-walled (SWNT) and multi-walled (MWNT).  I also put the pictures, for those  who never got the chance to see them before. As the name suggests they are simply very little tubes, but their big advantage for mechanics and electronics is that they are very robust (the most robust material on earth, in fact!) and electrically conductive.



If you want to think of nanotubes for electrical applications, you can consider them as a small cables for nano or micro electrical circuits (easy, they in fact look like small cables) or semiconducting parts of transistor (a bit more difficult).


If you want to think how to apply nanotube mechanical properties, it`s maybe a bit more difficult. One single nanotube is normally too small to be of any use for our world, but is you use big amount of nanotube you can use it to reinforce materials, such as polymers.


Now the last part, think of putting together mechanical and electrical properties of CNTs. One of the options is inducing vibrations of a nanotube (just as you make a guitar string vibrate), but not with mechanical force, but with electric field. (That was exactly the subject of my talk from the previous post!)


Apparently, those little vibrating systems present various interesting properties, quite different from macro-scale. Also resonators made of SWNTs are quite different of those ones made from MWNTs. They can have very good perspective for giga-hertz (GHz) frequency processing and mass sensing.
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My talk in IPN, Mexico, DF

Today I upload a few photos from my recent talk in Instituto Politecnico Nacional in Mexico City, where I came by invitation of  prof. Arturo Borquez.

It was a very exciting moment, first of all because it was my first serious, one-hour talk, but also because I was able to present the results of experiments on carbon nanotube resonators that I was working on during last year!




The announcement! Not yet a PhD, but it felt nice to see the dr title before my name! Of course later I had to explain the misunderstanding..




The introduction



Explaining the importance of nanotechnology


And finally the summary.. Are there any questions???


In the metro, happy with my little reconocimiento :)
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November in Catalunya

A short list of some of the upcoming events that you may find interesting.

ICMAB (Instituto de Ciencia de Materiales) in Barcelona offers a couple of interesting talks:

 4.11.2011
"Superconductivity at 100: Still alluring and hard to predict"  by Prof. PAUL CANFIELD (Laboratory Associate and Distinguished, Iowa State University, U.S.A.)

 7.11.2011
¨Algunos Óxidos Metálicos ocultan más de lo que enseñan…a primera vista: Viejos y Nuevos Materiales obtenidos a Alta Presión” by Prof. Miguel Ángel Alario y Franco (Laboratorio Complutense de Altas Presiones, Universidad Complutense de Madrid)

Another wokshop in ICMAB “Theoretical Approaches in Materials Science”, 14th November . More info http://www.icmab.es/theo2011

In Fira Barcelona will hold a conference about nanomedicine, with round table for doctors and scientists. Nanomedicina. La Ultima frontera. 16.11.2011


In Torre MAPFRE in Barcelona “II CONGRESO DE NUEVAS TECNOLOGIAS y sus repercusiones en el seguro”  (Internet, Biotecnología y Nanotecnología), 17-18.11.2011

 
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Green wrinkles



This is an optical microscope image of many-layers graphene, or maybe better just call it graphite, piece. The wrinkles appear during graphene exfoliation and they mark different crystalographic planes. The color is the result of microscope white balance option, in reality graphite pieces are silver-black.