RET@ND

RET 2009
This summer kicks off my second year in the RET program at Notre Dame. I will again be working with Dr. Xing in the Electrical Engineering department. My focus is quite similar, as I am still focusing on the creation of a functional nano-scale pH meter. However, there has been a material change. Last summer I was working with GaAs as a semiconducting material; whereas this summer, I will work on depositing (via a variety of methods) a thin sheet of graphene onto either silicon/silicon dioxide and/or copper foil. Graphene is especially exciting because it is theoretically a more energy efficient and “faster” material from which to build transistors. Silicon tends to hit a speed barrier around 10 nm, whereas graphene does not see this limitation.

New equipment: CVD furnace, AFM

RET 2008
This summer marked my entry into the RET program at Notre Dame. When I previously taught in Chicago I had been interested in a similar RET program at Northwestern University, but balked at the daily commute (Chicago traffic is HORRIBLE!). Having since moved to Indiana, I was up for the task of a daily 90+ mile roundtrip commute, even with gas prices being quite high.

I have been working with semiconducting materials over the past six weeks attempting to fabricate a functional ISFET that can be used as a pH meter.  My research experience is overseen by Dr. Grace Xing, who has provided a wealth of challenges to me.  Along with constructing a working ISFET pH meter, I have also been charged with presenting a series of talks on the book, “Crystal Fire“, by Michael Riordan and Lillian Hoddeson.  It is an excellent piece of non-fiction which details the invention of the transistor and the monumental shift in technology that came about as the result of its invention.  It served as not only a primer on transistors, but also as a way to connect with the other members of Dr. Xing’s group.

My presentations on Crystal Fire, as well as other presentations are saved at SlideShare
. SlideShare is an online presentation hosting site…great as a backup for powerpoints that you may use regularly or just would like to share with others. Slideshare is also a great safety net that enables you to upload your presentations such that if needed, you could present directly from the web using your uploaded presentation.

I spent the bulk of the summer reading various articles on ISFET devices, trying to figure out how I was going to go about making a functioning device.  To make a functional pH meter, an ISFET would serve to detect the ion concentration (in this case, the H+ ion) by the varying electrical potential upon the gate of the device that comes as a direct result of the conductivity of the electrolytic solution the device is submerged in.  A reference electrode provides a stable electrical potential to the electrolyte solution.  I made several Ag/AgCl reference electrodes, in addition to purchasing a stock Ag/AgCl reference electrode from Fisher Scientific.  I made a short video on how to make a reference electrode:

I have begun preliminary testing of my device, which is proving to be very “leaky”.  Basically, this means that current is flowing where it should not.  Although I have not made a device with is able to determine pH (yet!) , I have found some success in being able to determine the relative conductivity of electrolyte solutions that my device is immersed in.  The problem, as you can see below, is that my device cannot determine the difference between low pH values and high pH values, as both are very electrically conductive.

As my summer ‘08 experience is drawing to a close, I find myself looking expectantly to next summer.  I will again be working with Dr. Grace Xing and her research group, this time focusing on developing molecular sensors using graphene.  Imaging a device that can detect a particular molecule…fascinating stuff that is a real springboard from the research I was able to experience this summer.

If you are interested in joining one of the many RET programs at Notre Dame, a webpage has been established where you can apply as well as see the available research programs involved with RET@ND.  Feel free to contact me if you have particular questions regarding my experience at Notre Dame, or if you have general RET questions that you would like answered from a participants point of view.




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