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Archive for February 2012

Thinking big…while thinking small.

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Ever since people back home got whiff of the fact that I was doing a PhD in “Nanotechnology”, I am usually asked by eager friends and acquaintances about the latest and the greatest in the field. I always start out by saying that “nanotechnology” is in fact too generic a term for anyone to be an expert of,  and I know only a tiny little part of it, before launching into my view on all and sundry. After many a discussion and a talk to the local Rotary club, I thought maybe it would be good to post what I said as a starting point for a series on Nanotechnology. I often find that writing helps to crystallise my thoughts and understand things better, so this endeavour should be educational.

What is it? and why is it different?

A good starting point is to ask what nanotechnology is and what it encompasses. There does not seem to be a definition set in stone, but a commonly accepted (and in this case, heavily paraphrased) one is “any technology that derives its defining feature because some aspect of it is 100 nm or less in dimension“. So a bag of cement which derives some qualities (more strength, less weight etc) from the presence of 50 nm particles inside it is nanotechnology, while the Ipod Nano, however much Apple would like to claim so, is not.

Note: If you are unfamiliar with the nomenclature, a nanometer is a billionth of a meter. A human hair is roughly 50,000 nanometers. That should give a good idea of how small things are.

So what is different with nanotechnology? In the broad context, I would say nothing much is different. The same laws of physics apply as they do to micro, macro and mega-technology (if such words exist). What is different is the relative importance of each law when they act on different materials of different sizes. A good way to think about it is to conduct a thought experiment where we consider that every object is acted upon by gravity and some fictitious force that is pushing it away from the earth. Also assume that the fictitious force has a constant magnitude equal to that which gravity has on a 1kg mass. So how does this situation pan out for objects of different masses? For something human-sized (roughly 70-80Kg), gravity is about 70-80 times stronger and so dominant that the fictitious force will simply not be noticed. As we go to smaller objects, the relative strength of gravity decreases and that of the fictitious force increases. The tipping point is when the mass of the object reaches 1kg. Now both the forces exactly balance out and any object of 1kg will float in space. For objects smaller than 1kg, the fictitious force will be dominant and the the object will start shooting away from the surface of the earth, apparently by its own volition. The ability to float in empty space and shoot off against the pull of gravity may seem magical, but it is simply a change in the balance of forces that causes this apparent magic.

The balance of forces is a very simplistic example and nanotechnological phenomena involve more complicated things, but I find they almost invariably arise from this relative importance of different laws that arise due to small size or mass or specific structure. In my opinion, there are three broad categories that cause nanotechnological materials and devices to get their USP.

New materials.

One of the aspects of nanotechnology is the discovery of new materials that naturally exist at sizes small enough to merit the nanotech label. The classic examples of these are a few carbon based materials, such as carbon nanotubes (CNT), Graphene, Fullerenes etc. They arise out of the propensity of Carbon to form an immensely impressive array or structures (from coal to diamond for instance). CNTs and Graphene are being researched for applications as diverse as improving touchscreens, toughening materials, building electronics, improving battery energy storage and building space elevators.There are still issues with tractability though, and controlling these materials is not easily done.

New uses for known materials.

This is the domain of tweaking known materials such that we alter the balance of forces and tip it into doing what we would like it to.  A good example of such a case is for quantum dots, which are usually made by taking powders of known materials such as lead sulphide (PbS), Cadmium Selenide (CdSe) etc and blitzing them till they are turned into nanometre sized particles.This ultra-tiny size radically changes the properties of the particles vis-a-vis the orginal (mega-sized) powder and makes them more suitable for certain applications. This is a case of an existing material, simply being cast into a different form, so that it takes on different properties and potential applications.

Existing materials in innovation strutures.

Tweaking the balance of forces can also be accomplished by using known materials in innovative strutures rather that simply blitzing them as in the case of quantum dots. A classic example of this is the wing of a Morpho Rhetenor butterfly, a species originating from South America. The wings of this butterfly are shimmering and  brightly coloured, but surprisingly not due to the presence of a dye or any pigmentation. It is in fact due to an elaborate structure of the wing, which involves alternate layers of two different materials, each a few nanometres thick. The thickness of these layers is of a similar magnitude to the wavelengths of incident light and the resulting interaction produces the bright colours that make the butterfly so striking. An exploration into this structure is opening up a whole new area of research focussing on what is known as the “photonic bandgap” and which could have very interesting applications in the future.

So there we have it, my three tier classification of nanotechnology. This is just an introduction, so that the post is long enough to provide information while being short enough to maintain interest. I will examine more detail in further posts as I learn new stuff, which may be tomorrow, the day after, or never, depending on what I am upto otherwise. 🙂

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Written by clueso

February 28, 2012 at 7:34 am

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Education unchained?

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Some time ago, I blogged about my idea of an education system that separated exams from learning and thereby allowed students to have more liberty in choosing how to get the classroom component of their education while earning their desired qualification. Today I learnt of MIT’s new fully automated course on circuits and electronics. MIT have run the open courseware project for a while now, but it was more of a reference point, where people could sample the lecture notes that MIT uses, but do not get credit for reading the notes or completing the exercises. This course however, offers a certificate for completion, which means that any person, anywhere in the world can now gain an MIT recognition of his/her skills from the comfort of their home.

Arguably, if this course gets a large enough market, someone may start a coaching class to help students understand the material. That would in essence be the separation of the classroom teaching component of education from the exam component, akin to what my old post suggested. Maybe those bright sparks at MIT were reading my blog, though I have my doubts about that.

A fully automated course is nevertheless something noteworthy. I am especially interested in how they handled the lab component. Do they purely use circuit simulators? do they plan to extend the idea in the future where there are accredited venues where students can go to complete the labs? Will the exams be purely multiple choice questions or have they devised a way to have computers grade exam papers? I have enrolled for it, so hopefully sometime in June (when the course ends), I will be able to proudly claim to have a certificate from MIT and also be able to report on my experiences.

While this new development has me excited about the direction education can take in this century,  I can think of a few undesirable implications of rolling out multiple courses or entire degrees through this avenue. Someday soon, I will put those thoughts down too.

Written by clueso

February 14, 2012 at 8:15 am