Au Revoir!

As I'm sitting on the bus back home, typing this… I realize something: my computer is actually connected to the Internet! 

It's a refreshing change only because wireless networks were often jammed throughout the conference, as could be expected when 5000+ people -and almost just as many laptops- descend upon a building. However, it looks like the Hynes Convention Centre has recognized the problem: signs are posted everywhere announcing that $20 million will be pumped into the facilities within the next year "to increase connectivity and to make the meeting spaces better". 

So, connectivity to the world re-established, this concludes my final post to the MRS blog! The only thing left to say is that I regret not going to a few more talks outside my comfort zone. Looking back through the program, the presentations in Symposium WW on Materials Issues in Art and Archeology look particularly tempting for next year!

Au revoir!

Matthew

Blast From the Past: Fred Kavli Distinguished Lecture in Nanoscience

Hey!

As I was preparing to sign-off from the blog, I noticed that one of my earlier posts hadn't gone through (blame the spotty connectivity). So, just in case you're interested in hearing about it again, here's a trackback to Sunday's Fred Kavli Distinguished Lecture in Nanoscience...

Just got out of the Fred Kavli Distinguished Lecture in Nanoscience, and distinguished it was! Prof. Charles Lieber of Harvard University presented a dense lecture entitled Semiconductor Nanowires: A Platform for Nanoscience and Nanotechnology in which he discussed a large proportion of his group's recent research. While George Whitesides is definitely established as Harvard's big man on campus when it comes to self-assembly or micro-scale phenomena, Prof. Lieber seems to have made a name for himself on the nanoscale. Despite Prof. Lieber's background in Chemistry, the presentation was pretty devoid of synthetic schemes, focusing instead on the applications of his work to low-dimensional systems. He broke it up into two sections, the first of which covered the properties of nanostructured photovoltaic (PV) nanowires, with the second dealing with interfaces between nanoelectronic and biological materials. 

Part I - Nanowires
The first question Lieber looked to answer was: What makes an ideal system? He emphasized the need to have materials with tuneable compositions and properties. Looking at the example of Silicon (Si), he remarked that Si only really becomes useful when it is combined with other compounds. With this in mind he demonstrated how materials with determined and determinable properties can be created, in a fairly ab initio manner, by employing hybrid multicomponent materials as building blocks. He elaborated on this idea by presenting some radial core/shell nanostructures composed of single-crystalline Germanium (Ge) cores over which epitaxial Sillicon shells had been grown (i.e. over which Si had been grown in such a manner that its crystalline orientation is the same as that of the Ge core). Lieber specified that this core/shell structure effectively isolated the core from surface effects/inhomogeneities present on substrates and showed how, in some cases, this resulted in semiconductor mobilities approaching the ballistic limit! 


Lieber the presented an extension of this idea, whereby an extra layer was added between the core and shell to yield p-i-n layered nanostructures with photovoltaic properties. Among the more impressive figures mentioned, Lieber presented a nanowire PV device with an open-circuit voltage (Voc) of 0.260 V, and concomitant operational stability of 12+ months. Lieber provided other examples of structures for which the Voc achieved neared 0.5 V: quasi ideal values. He also showed how his team was attempting to understand the fundamental limits to core/shell nanowires by looking into the absolute quantum efficiencies of several of the different organic structures. Interestingly, by slightly varying the composition of the PV nanowires, Lieber was able to tune the nanowire's absorption spectrum to absorb most strongly in the regions of high solar optical density. The take home message of this part, though, I think was that nanowire PVs are sufficiently developed to be able to use them as power output sources for nanoelectronic chips!



Part II - Interface between Biology and Nanoelectronics
There are many examples of technologies which require electronics to interface with biological components (for instance, EKGs). However, electronic components and devices have yet to be merged anywhere near to the scale of natural, biological processes. That is to say, the probes we currently use to interface with biological systems are orders of magnitude larger than the ion channels, substrate synapses and signalling molecules which compose biological systems. Charles Lieber's vision of the future in this regard is can be compared to the history of computing: he is persuaded that we are in the age of vacuum tubes (micro-scale probes) and that once we make the big step towards solid-state transistors (nanoscale probes), sweeping improvements will result. 

As device dimensions keep decreasing, a critical parameter (the surface to volume ratio) will keep increasing, resulting in increasing device sensitivity. For example, we can now complete multiplex room temperature detection of disease markers, including single viruses, with 100 billion fold sensitivity! The field is still progressing towards the detection of single molecules and, more importantly, towards the detection of single molecule binding events. Lieber then related a number of examples of his team's work in this regard, including designing nano-scale tips for cellular patch-clamping experiments.


Good night!

Friday!

The talks I attended on Friday were much more theoretical than those I had seen in previous days. Some of the highlights were:

David Gundlach's presentation, entitled Why Contacts Matter, was a discussion on the difficulty of separating contact effects from material properties in charge transport studies. The main point was to show how analysis of a device can be obscured by the voltage drop at the contacts.



Alessandro Morgera, from the Italian synchrotron facility in Trieste (yes, they have a synchrotron in Trieste!) showed how he had used a model system of 4-hydroxycyanobenzene (4HCB) single crystals to perform Electronic Anisotropic Transport studies with an IR-based setup in the synchrotron.



Dave Herman's talk, entitled Nanoscale Co-assembly of Zinc Oxide and Conjugated Organic Molecules in Oriented Macroscopic Films via Electrodeposition, discussed ways in which we can play with the orientation of hybrid lamellar structures inside bulk heterojunctions. The main goal of his work is to induce interdigitation on 10 nm length-scales, in order to optimize exciton diffusion and charge splitting/diffusion.

Signing off

I am back in Texas and signing off with a few thoughts. I am a big believer in the law of the universe, which goes something like this. If you believe in something (say a research objective or a personal quest) and keep an open, positive mind about it, every force in the universe will try to bring you closer to your goal. I put this theory to the test at the MRS conference this year and I believe it worked. The talks I attended, the posters I saw, the blogs and tweets and even the conversations I had seemed to give me clues and answers to questions that had been bothering me for quite sometime. From reading other posts here, looks like other bloggers have had similar experiences too.

So let me then conclude by saying thank you for this opportunity, and thank you to all my fellow bloggers and tweeters. I plan to continue blogging and hope to see you all again at SFO.

 

Last Note

As my first MRS experience, this week has been amazing. I have enjoyed listening to all kinds of crazy talks and even just walking through the hallways hearing what people are talking about. I've always loved blogging, so having a legit excuse to do it daily also added to the fun. =)

See you all next time!

Thank you ...and good night!

For my last post on the MRS blog, I want to thank MRS for this opportunity as well as my fellow bloggers and tweeters.  The meeting was very informative and loads of fun, and being able to interact with everyone through the blog and twitter made it even better.  This was a great chance to attend the conference but view it from a new perspective.  I hope the other bloggers enjoyed posting as much as I did and I hope the readers were able to gain from what we wrote.  I am excited for the potential of these activities to change the way attendees experience MRS, especially as the popularity of twitter and blogging expands within the materials community.

As a farewell, I would like to offer up another challenge to you the reader.  With the explosion of social media, there is a lot of emphasis on interaction with other people.  As a materials scientists, I feel there has to be some form of pun or joke involving van der Waals interactions.   After a week at MRS, my brain needs a bit of rest, but I challenge you to find this pun/joke.  All of the talks this week touched on the importance of materials science in the world today, don't forget about the importance of fun in materials science.  Embrace your inner nerd!

 

-Trevor

Hindsight

I am taking this afternoon to wander around the Boston area near the convention center.  In my wanderings, I realized something that maybe I should have done...researched the area before coming to the conference.  With the jam packed schedule of the conference, there is not exactly time for site seeing, but we still need to eat.  Most people, I saw, had no trouble finding a quick lunch at the mall, but sometimes you want to sit down to a nice meal, or maybe have a beer to celebrate winning that poster competition.  If I were to repeat this blogging experience, maybe some quick googling and a short post on a nice place to get a burger and a drink would have been helpful to my fellow scientists. 

I am fortunate to be staying with friends who were able to point me in the direction of a few places that they knew I would like, but not everyone has that benefit.  For all the others that traveled some distance to Boston, hopefully you got to see more than the inside of the convention center.  Even if it was just to step outside breifly and enjoy the surprisingly good weather this week.

Carbon Nanotubes

On this final morning of MRS, I went to a few talks that were not really related to my research.  I think it is refreshing to be able to listen to a talk out of just curiosity for a subject outside or my comfort zone.  So I wandered into some discussions on carbon nanotubes and listened in on what people were doing. 

The discussions after the talks were very interesting because the audience would not let any speakers off the hook to easy.  While there wasn't any heckling, there were some very specific and nit-picky type questions.  Fortunately the speakers handled themselves well and everything continued as a discussion rather than a one sided argument.

The most incredible, in my opinion, talk of the morning was about the temperature independent viscoelastic properties of carbon nanotubes.  The speaker had a very high energy and the presentation had plenty of visual depictions of the material properties as well as videos showing her material in action.  Even the name of the group was clever The Super Growth CNT Team.

I hope you were able to venture outside your specific research area and learn something new this week.

One less experiment to do after I get back

Just before coming to Boston, I had been trying to grow Cu oxide films by a sol-gel method and must say didn't have much success. I was planning to try out few more ideas after getting back. Guess what, walking through the poster session, I discovered a poster describing exactly what I needed. Better yet, my original method was not wrong, it just missed a simple step. I had to store my sol for a day before using it. That's it....can't wait to get back and try this. Thanks MRS :-)

P.S. If anybody needs more details, feel free to post a comment here and I can send you the recipe.

 

Thursday - Poster Session

One theme I saw throughout the conference, but particularly in the Thursday poster session, is the desire to decrease the cost of producing any given structure.  One common method seems to be ink jet printng of structures, but each poster had it's own unique flavor with regard to technique or material types.  I know that this is a hot topic right now-- what if, instead of cleanroom processing that requires special training, expensive tooling, and the use of harsh chemicals, anyone with a printer could print circuits or other devices?  It's an interesting concept, and I can understand why it is such a popular topic. 

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