Two of the most promising fuel cell technologies are PEMFCs and DCFCs. The first one is a proton exchange membrane fuel cell, also known as polymer electrolyte membrane fuel cells. The effectiveness of this kind of device depends on the proton conductivity of the polymer electrolyte. On the other hand, DMFCs (direct methanol fuel cells) use methanol as main fuel and have a polymer as electrolyte. The methanol is oxidized in the presence of water at the anode and their only waste products are water and carbon dioxide. A problem with DMFCs is that the electrolyte material is very expensive. Thus, the creation of suitable materials for PEMFCs and DCFCs is something that researchers can possibly find through nanotechnology.

The research group at MIT led by Paula T. Hammond, has discovered a material for DMFCs by using a LBL assembly (Layer-by-Layer) technique, a method for thin films fabrication. Their technique is based in sulfonating a stable aromatic polyether and pairing it with other functionalized polymer. They first built thin films of two different polymers and then put them together to achieve a material with high proton conductivity and mechanical stability.  These films also have a low methanol permeability which is very useful in DMFC. Moreover, tests reported an increase in power output of more than 50 percent.  This kind of energy storage device has the advantage of being environmentally friendly as well as having the potential to improve electronic devices.

Angelica Azcatl, CNSE Intern
July 8, 2008

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For the past few days I have continued my attempts at understanding how to write scripts in MATlab and today all my efforts came together in a script for a program. Without getting into too much detail the script is basically helping identify outgassing elements that are in our chambers. Since I just wrote it today the script works but needs a lot of tweaking before it provides the best results. In the meantime as I was looking at other options to provide the answers the team is looking for, I was told to look up simulated annealing. Simulated annealing is an algorithm that is typically used for optimization problems that become insurmountable. It is said that simulated annealing is best used for the "Traveling Salesman Problem", click here to learn more about simulated annealing. Hopefully after reading about this method I can come up with an efficient way to identify the outgassing elements.

Emily Michlewski, CNSE Intern
July 8, 2008

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The photoelectric effect was one of the first physical phenomena not explained by classical physics.  It states that when a surface is exposed to electromagnetic radiation above a certain threshold frequency, the light is absorbed and then electrons are emitted.  The energy of photons depends on the frequency of the light and if a photon which has more energy than the work function of the electron, it is absorbed by that electron and that electron is emitted.  Different materials have different work functions; the work function is the minimum amount of energy that needs to be absorbed before electrons are emitted.  We use Xenon plasma which emits Extreme Ultraviolet radiation to excite our electrons.  I measure the photoelectron yield using a picoammeter.  It is thought that there is some correlation between the photoelectron yield of a material and its rate of contamination.

Kathleen Tracey, CNSE Intern
July 7, 2008

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Over the last couple weeks, I have been steadily working on my project.  However, so far I've done a lot of my work generally helping out with other projects, which is helpful because I get to learn a lot about the different tools we are using to do experiments.  Just yesterday the last part that I needed to get my project done came in, so shortly I will be in full swing to try to get my device up and running allowing me to test it for leaks and general effectiveness. 

Kyle Watters, CNSE Intern
July 3, 2008

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Recently, researchers have made a discovery which could be an important step in the pioneering field of molecular electronics. By developing a way to attach light-sensitive molecules to a metal substrate, they were able to produce light-driven reversible nanoswitches. The chosen molecule is azobenzene which is made up of two nitrogen atoms connected by a double bond with a benzene ring attached to each nitrogen atom. When exposed to ultraviolet light, the azobenzene molecule switches from the trans configuration (benzene rings on opposite sides of the molecule) to the cis configuration (benzene rings on same side of the molecule). Upon exposure to visible light, the molecules switches from cis back to trans. In order to make use of this mechanism, the molecule must be anchored to a substrate. By developing a tether which isolates the azobenzene molecules from other molecules and from the substrate, researchers at Penn State University and Rice University, were able to overcome the interactions that had previously prevented switching of attached molecules. For more information, click here.

Georgia Russell, CNSE Intern
July 2, 2008

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Currently, the software for the modeling, design and simulation of electrical devices is a common tool for the development of new technology. For nanotechnology, such tools are very useful for analysis and prediction of the performance of nanodevices. With software we can also solve complex equations that describe nanoscale systems. In fact, many semiconductor manufacturing companies all over the world have incorporated the computer simulation for the optimization of their technologies and to be part of global competition.

TCAD (Technology Computer Aided Design) for example, offers varied products for the device simulations and is widely used in semiconductor manufacturing. Sentaurus TCAD software, which is related with the project I am working on, combines advanced models, algorithms and meshing for simulations in 1D, 2D and 3D of electrical devices such CMOS, bipolar transistors, memories, optoelectronic devices, sensors and other novel devices. Also, it allows for improving the manufacturing process and is a potential tool for nanodevice development.  For more information, click here.

Angelica Azcatl, CNSE Intern
July 2, 2008

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German and Korean scientists of the Max Planck Institute and Pohang University have developed a technique to produce some extremely small capacitors. These nanoscale capacitors have allowed the scientists to achieve a solid state memory density never before realized. In fact, the achieved density of 176 billion bits per square inch is a world record. To give you some idea of what that means, present memory capacity approaches only a few hundred million bits per square inch. This has some obvious applications in the electronics industry as the push to make things smaller is ever present, as is the demand for higher memory capacity to store more music, videos, games, etc. To learn more about the nanoscale production of these tiny capacitors and their applications, click here.

Chris Simpson, CNSE Intern
July 2, 2008