Category Archives: Nanotechnology

Carbon Nanotubes: An Allotrope Worth More than Diamonds?

Recently I read a BBC article that both confused and intrigued me. The article was about a Stanford University engineering team and their creation, the “first computer built entirely with carbon nanotubes.” (Morgan, 2013) This reminded me of graphene, a singular sheet of covalently bonded carbon atoms in hexagonal rings, that had come up in class. Remember that graphite is one of the allotropes of carbon along with diamond and the C60 fullerene and that graphene is a single layer of the carbon sheets that make up graphite. (Graphene: World-leading Research and Development, 2012) Interestingly enough, India and Vhristi have both written on graphene, and nanotubes respectively, but through wider and more introductory lens; I hope to focus my research on the application of nanotubes in electronics. Thus with this foundation, I decided to investigate further the one claim the article brought up that really fascinated me, that carbon nanotubes could eventually replace silicon chips as the linchpin of modern electronics. (Hsu, 2013)

Carbon Nanotube Arrangements
Carbon Nanotube Arrangements

Single-walled carbon nanotubes are sheets of graphene rolled up into a cylinder; depending on the direction in which the sheet is rolled, the nanotube will possess different physical properties. (Nanocyl, 2009) Extreme strength, up a hundred times stronger than steel, while maintaining lightness is one of the characteristics that have made scientists so interested in carbon nanotubes. (Bonsor & Strickland, 2007) The other is the ability to act as a semiconductor, a substance with conductivity less than that of most metals but greater than that of an insulator. (Forbus) Currently, the heart of the ubiquitous tablets, computers, and smartphones is the silicon transistor, a semiconductor switch that allow for the control of electrical signals. (Brain, 2001) To keep up with society’s demand for smaller, lighter, and faster devices, engineers have had to shrink transistors. (Hsu, 2013) However as silicon transistors get smaller, with the smallest being Intel’s 22-nanometer Ivy Bridge model, more of the energy that goes in is transformed into heat and wasted. This physical limitation has prompted research into carbon nanotubes as an alternative because of their minute size and “energy-efficiency at small sizes.” (Hsu, 2013)

So, after establishing that carbon nanotubes, theoretically, could outclass the silicon chip I went back to the BBC article to ask: what does this ‘landmark computer’ really mean for the future of carbon nanotube technology? While the computer the Stanford team, led by Subhasish Mitra and H.S. Philip Wong, created is only an elementary prototype that can only count to 32, it is definitive proof a computer could be made solely from nanotubes. (Morgan, 2013) The process in which they arrived at the computer also made great strides in use of nanotubes in electronics. The team aligned the naturally misaligned nanotubes in chips with only 0.5% disparity, designed an algorithm to bypass those that were skewed, and vaporized the “metallic” nanotubes that always conducted electricity. (Shulaker, Hills, Patil, Wei, Chen & Wong, 2013) Although these improvements have streamlined the process of creating carbon nanotube based nanoelectronics the 8000-nanometer transistors are still far from being able to compete economically or technically with silicon chips. (Palmer, 2012)

Carbon Nanotube Transistor
Carbon Nanotube Transistor

Given that silicon chips will eventually reach their limits, this test has shown that carbon nanotubes are progressing as a viable replacement for the current industry standard. (Hsu, 2013) An economic implication of this development is that if the nanotubes keep making significant progress, this possibly more efficient option to the silicon chip will be met with great demand in our technology driven society from firms and governments, the former to produce the next-generation of electronics, and the latter to improve domestic technological and military infrastructure. Just like the silicon chip allowed for a surge in technological innovation, carbon nanotubes could too engender its own rush of progress. A more short-term implication of this auspicious advancement will be reenergized investment and resources dedicated to nanotube research by firms and laboratories not wanting to be beaten to the possible patent of the next half century. But for carbon nanotubes to make the transition from laboratory to factory to store shelf will be costly and time-consuming. One must consider the economic and technological quandaries that will undoubtedly arise as this technology advances, as with all innovations. How can we mass-produce carbon nanotube transistors? How do we maintain a high quality when dealing with such tiny basic components? Each is a question that must be resolved before this new technology hits the shelves.

But I have to say, after reading about the nanotube computer I felt genuinely excited. I know that many obstacles stand in the way of carbon nanotube devices, especially the development of a cost-effective means of mass-producing nanotube transistors. On the surface this seems like a classic case of a scientifically sound theory without any means of practical execution but in this case I have hope. Ever since I have remembered I’ve been waiting for that futuristic advancement that really ushers in a new technological age like home computers and mobile phones did in the 1990s. If this it, I have hope that some combination of entrepreneurship, capitalism, and scientific curiosity will see carbon nanotube technology commercially possible, if not in our smart houses, supercomputers, and flying cars.


BBC. (2011, May 04). Intel unveils 22nm 3d ivy bridge processor. Retrieved from

Brain, M. (2001, April 25). How semiconductors work. Retrieved from

Forbus, K. D. (n.d.). Retrieved from

Hsu, J. (2013, September 26). Carbon nanotube computer hints at future beyond silicon semiconductors. Scientific American, Retrieved from

Morgan, J. (2013, September 25). First computer made of carbon nanotubes is unveiled. Retrieved from

Nanocyl. (2009). Single-wall nanotubes (swnt). Retrieved from

Palmer, J. (2012, October 12). Carbon nanotubes fit by the thousands onto a chip. Retrieved from

Shulaker, M. M., Hills, G., Patil, N., Wei, H., Chen, H. -., & Wong, H. -. P. (2013). Carbon nanotube computer. Nature, (501), 526-530. Retrieved from

(Graphene: World-leading Research and Development, 2012)The University of Manchester.(2012). Graphene is going to revolutionize the 21st Century. Retrieved 24 December, 2012, from

Image Sources:

Groeben, N. V. D. (Photographer). (2013, September 25). Hand holding cnt wafer [Web Photo]. Retrieved from

How Stuff Works. (Designer). (2007, October ). Nanotechnology [Web Photo]. Retrieved from

Fun in the Sun

I got my first sunburn this summer (ouch) because I forgot to put on sunscreen. Actually, I pretty much forgot to use sun protectant the whole summer. That got me thinking about sunscreen. It’s just something that we rub onto our bodies, so how does it protect our skin? So in this post I’m going to investigate how sunscreen works, why it’s important to protect your skin from the sun, and how to do so.

The reason we need to protect our skin is because of the UV rays that are present in sunlight. UV rays come in wavelengths from 10nm to 400nm, but there are 3 main categories: UVA (315-400nm), UVB (280-315nm), and UVC (100-280nm). UV radiation has “low penetration” so its effects are mainly limited to the skin. (Encyclopædia Britannica, 2013)

(Skin Cancer Foundation, 2013) – diagram of UV ray penetration of skin

UVC rays are completely absorbed by the Earth’s atmosphere, so we don’t need to worry about that. It’s the UVA and UVB rays that cause trouble. UVB rays are the ones responsible for sunburns and suntans. (Everyday Mysteries: Fun Science Facts from the Library of Congress, 2010) UVA rays, since they have a longer wavelength, penetrate deeper and are the main cause of wrinkles and age spots. (Bytesize Science, 2012) UVA rays can also penetrate through clouds and glass, and 99% of the UV rays that reach the Earth’s surface are UVA rays. (Encyclopædia Britannica, 2013) Both UVA and UVB rays can cause skin cancer. (US Food and Drug Administraton, 2011) Also, sun exposure is responsible for 90% of wrinkles! (Youtube, 2013)

To protect ourselves from these UV rays, sunscreens were invented. There are two types of sun protectants available: chemical and physical sunscreens. Physical sunscreens, also known as inorganic sunscreens, are made out of nanoparticles that are approximately 100nm. They act as tiny reflectors on the skin to deflect and scatter the UV rays that shine onto our skin. (PBS Newshour, 2010) The large particle size is also what attributes to the “white cast” look of sunscreen on the skin. ( Chemistry, n.d.) Typical ingredients in physical sunscreens are titanium dioxide and zinc oxide.

physical sunscreen

(Bytesize Science, 2012) – structures of titanium dioxide and zinc oxide

Chemical sunscreens, also known as organic sunscreens, are much smaller in size, around 40-50nm. The small sizes of the nanoparticles allow it to be more transparent than physical sunscreens. (PBS Newshour, 2010) The most common ingredients in chemical sunscreens are octinoxate and avobenzone. (Bytesize Science, 2012)

chemical sunscreen

(Bytesize Science, 2012) – skeletal structure of octinoxate and avobenzone

Unlike physical sunscreen, chemical sunscreens protect the skin by absorbing the UV rays instead of reflecting it. The molecules in the sunscreen absorb the high-energy UV photons, and the electrons become “excited.” When the molecule returns to its original state, the energy it absorbed is released as insignificant amounts of heat. This process can be done more than once, in a cycle. (Nonprescription Drug Manufacturers Association and Cosmetic, Toiletry, And Fragrance Association, 1998)

Yikes, those UV rays don’t sound nice at all. In the interest of having younger looking skin, not getting a nasty sunburn, and preventing skin cancer, protecting our skin from the sun is a must. Physical sunscreens can only defend our skin from UVB rays, but chemical sunscreens can protect our skin from both. So when buying sunscreen, look for products that are labeled “broad spectrum” or have a PA value because those indicate both UVB and UVA protection. (Youtube, 2013)

(Youngerberg, 2013) – sunblock that have UVA and UVB protection

SPF, which stands for “sun protection factor,” can be a useful way of determining the effects of sunscreen. If your skin can stand 10 minutes in the sun without burning, then a SPF of 30 will allow your skin to be out in the sun for 30×10, or 300 minutes (5 hours), before burning. ( Chemistry, 2010)  Keep in mind that most people don’t put on enough sunscreen (a shot glass worth, or 45mL, of sunscreen is what’s recommended to cover your body), and sweat and water can make the sunscreen less effective, so it is important to reapply sunscreen often (around every 2 hours if you’re active).

It seems that I’ve found the fountain of youth – sunscreen! The next time you’re out in the sun, remember to protect yourself from those pesky UV rays, and do yourself a favor by putting on sunscreen. You’ll thank yourself when you’re older!

References Chemistry (n.d.). How Does Sunscreen Work?. [online] Retrieved from: [Accessed: 19 Sep 2013]. Chemistry (2010). How to Choose the Best Sunscreen. [online] Retrieved from: [Accessed: 19 Sep 2013]. Pediatrics (2010). SPF – Sun Protection Factor and Sunscreen. [online] Retrieved from: [Accessed: 19 Sep 2013].

Bytesize Science (2012). Repelling the Rays: The Chemistry of Sunscreen – Bytesize Science. Available at: [Accessed: 19 Sep 2013].

Discovery Fit and Health (n.d.). What do SPF numbers mean?. [online] Retrieved from: [Accessed: 19 Sep 2013].

Everyday Mysteries: Fun Science Facts from the Library of Congress (2010). How does sunscreen work?. [online] Retrieved from: [Accessed: 19 Sep 2013].

Gizmodo (2013). How Sunscreen Works (And Why You’re Wrong About It). [online] Retrieved from: [Accessed: 19 Sep 2013].

Live Science (2010). How Does Sunscreen Work?. [online] Retrieved from: [Accessed: 19 Sep 2013].

Nonprescription Drug Manufacturers Association and Cosmetic, Toiletry, And Fragrance Association (1998). Tentative Final Monograph for OTC Sunscreen. [e-book] Food and Drug Administration. Available through: [Accessed: 19 Sep 2013].

PBS Newsroom (2010). Just Ask: How Does Sunscreen Work?. [online] Retrieved from: [Accessed: 19 Sep 2013].

Science & Engineering News (2002). C&EN: WHAT’S THAT STUFF? – SUNSCREENS. [online] Retrieved from: [Accessed: 19 Sep 2013].

ultraviolet radiation. (2013). In Encyclopædia Britannica. Retrieved from

US Food and Drug Administration (2011). How Sunscreen Works. Available at: [Accessed: 19 Sep 2013].

Youtube (2013). The Ultimate Guide to Sunscreen. Available at: [Accessed: 19 Sep 2013].


Bytesize Science (2012). Repelling the Rays: The Chemistry of Sunscreen – Bytesize Science. [image online] Available at: [Accessed: 19 Sep 2013].

Bytesize Science (2012). Repelling the Rays: The Chemistry of Sunscreen – Bytesize Science. [image online] Available at: [Accessed: 19 Sep 2013].

Skin Cancer Foundation (2013). Untitled. [image online] Available at: [Accessed: 22 Sep 2013].

Youngerberg, E. (2013). Untitled. [image online] Available at: [Accessed: 22 Sep 2013].

Nanotechnology: A Source of Free Energy?

Recently, I have been researching on alternative energy sources as part of a Chemistry related science club presentation. Solar panels, hydroelectric dams, wind turbines, geothermal heat pumps, were the first ideas that popped into my mind. We commonly hear about these forms of technology that are used to harness the renewable energy sources that are available to us and significant research and development have vastly improved our efficiency in utilizing these sources. However, many of these options are of larger scales and as an individual consumer, we may not have the capability or accessibility to switch towards these renewable sources even if we wanted to. Researching further into smaller scale forms of renewable energy technology, I found that innovations of all sizes are taking place, the most interesting of which is in the nascent field of nanotechnology used in harnessing solar power.

A Ted Talks by Justin Hall-Tipping, founder of a nanotechnology based energy research company called Nanoholdings, discusses some of his latest creations on how to “generate, transmit, store, and use”(Nanoholdings) solar power. Initially, he began with a common problem of the transfer of heat energy through windows in a home. The picture below illustrates how in the summer, the energy coming from the sun is heating the home that we are trying to keep cool, while in the winter, the heat is escaping from the home we are trying to keep warm.

Screen shot 2011-11-09 at 11.22.52 PM

Aiming to give consumers the ability to control the heat transfer occurring through their windows, Nanoholdings’s nanotechnology material uses Carbon, which undergoes a reaction where “graphite is blasted by a vapor, and when the vaporized Carbon condenses, it condenses back into a different form…called a Carbon nanotube”(Hall-Tipping).

Screen shot 2011-11-09 at 11.37.02 PMScreen shot 2011-11-09 at 11.37.44 PM

Vaporizing Carbon                             Structure of Carbon Nanotube

The unique thing about this nanotube is that it is “a hundred thousand times smaller than the width of one of your hairs” and “a thousand times more conductive than Copper”(Hall-Tipping). Because Carbon at the nanoscale behaves and looks very differently, instead of being black and solid, it is actually transparent and flexible. Combined with a plastic during manufacturing, this Carbon nanotube can actually undergo permanent changes in color by using merely “two volts from a millisecond pulse” (Hall-Tipping) per color change. If this material were used on a window, in its colored state, it will reflect away all heat energy from the sun, helping to insulate a cool home. Vice versa, while in its transparent state, it will allow all heat energy from the sun to pass through, helping to warm a home.

Screen shot 2011-11-09 at 11.41.19 PMScreen shot 2011-11-09 at 11.41.26 PM

Transparent Carbon Nanotube            Colored Carbon Nanotube

Another ongoing project at Nanoholdings called “NIRVision”, uses nanotechnology like above to develop “flexible, thin films…to convert infrared light into visible light”(Nanoholdings). Similar to how more modern night-vision goggles work, a “photo-detector film converts invisible infrared light into electrons…these electrons stimulate an optical film like a thin flexible display, to create a visible image”(Nanoholdings). As we know, the flow of electrons is a source of electrical energy. Hall-Tipping goes on to describe how if we combined the film created in NIRVision with the Carbon nanotube illustrated above, then we would have a material that takes “infrared radiation and converts it into electrons” (Hall-Tipping) and because of its flexibility and transparency, we would be able to attach it to any surface to ultimately become a free source of clean energy.

The applications of this nanotechnology-developed material are endless, as a free source of clean energy is the solution to both our rising energy demand and our Earth’s rising temperature. Unfortunately, this material is still being tested and until we are able to efficiently manufacture it at a low cost to the environment, we must continue our gradual movement towards renewable sources of energy and a more environmentally conscious mindset. Similar to Steven’s post on the revolutionary perspective of silk, Nanoholdings was able to take one of the most common and abundant elements, Carbon, view it from a different perspective, and alter it in a way as to develop a material with new and desired properties. An even greater implication lies in how Hall-Tipping is able to combine two different technologies with different applications and generate a new one with completely new applications. Developing brand new technology may be life changing, but sometimes the most sublime of solutions can lie in how well we can take advantage of what we already have.

Works Cited

Hall-Tipping, Justin. “Justin Hall-Tipping: Freeing Energy from the Grid | Video on” TED: Ideas worth Spreading. TED Conferences, Oct. 2011. Web. 09 Nov. 2011. <>.

Nanoholdings. “Nanoholdings – Portfolio – New Technologies – Nirvision.” Nanoholdings. Nanoholdings LLC. Web. 09 Nov. 2011. <>.

(An Invisible Title)

Harry Potter Invisibility Cloak

“I am Harry Potter and this is my invisibility cloak! Look – now you see me… and now you don’t!” The eleven year old me gushed as I was getting ready for a night of trick-or-treating.

“It is just a black cloak wrapped around you, I still see you.” That was when I realized that invisibility was only possible in Harry’s magical world.

Or is it?

Recently, I stumbled across an article that claimed that scientists have created an invisibility cloak by using the ‘mirage effect’. Propelled by my childhood dream to possess such a cloak, I began to delve further into this topic. Before we can move into the science behind how such a cloak is made, we need to first understand the concept of refraction, how the human eye perceives objects and how this leads to the mirage effect. Humans are able to see an object because light waves are reflected or refracted (bent) from the object and then travel to the human eye. Sometimes, however, light waves from an object pass through another medium and bend the light wave another direction. Imagine, for instance, a spoon inside a glass of water – when inside a glass of water, the spoon appears to be ‘broken’. This is because the light waves reflected from the part of the spoon submerged under water, are refracted when they pass through the surface of water. Unfortunately, our brain does not know the light waves from the spoon have been refracted, and thus we perceive the spoon to be at different position under water. Figure 1 below further explains this concept.

Concept of Refraction

Figure 1: Concept of Refraction

The mirage effect is based off this concept. Many of you must have probably experienced driving down a road on a hot summer day and seeing a pool of water in the distance, only to realize that it was actually a mirage. Mirages form because of a temperature gradient between the air and surface of the ground. Usually, light waves from the blue sky are reflected off the surface of a road and thus allow us to see the road ahead. However, in a mirage, a very hot surface causes the light waves from the sky to refract before coming in contact with the road. Since our brain does not know the light wave has been bent, the eye traces the light wave in a straight line to the ground, thus causing our eyes to incorrectly perceive the light waves as a pool of water in the distance (when it is actually refracted light waves from the sky).

Using the concept of the mirage effect, scientists have made an invisibility cloak out of a lattice of carbon nanotubes that when electrically stimulated, either by electrical heating or by a pulse of electromagnetic radiation, create a temperature gradient that cause light waves to bend away from whatever object is under the invisibility cloak. The most important aspect of such an invisibility cloak is the lattice of carbon nanotubes. In order to bend visible light waves, the lattice of carbon nanotubes (also known as metamaterial) must be spaced less than the wavelength of visible light. Till now, researchers have only been able to succeed with near-infrared radiation as our technology is not sophisticated enough as yet to create a lattice with smaller spaces between the carbon nanotubes. Thus, until scientists are able to create a lattice small enough to bend light waves from the visible spectrum, an object will remain visible to the human eye.

Refraction of Light Waves to make Object Invisible

Figure 2: An object covered in an invisibility cloak made of carbon nanotubes that bend the light waves around the object, making the object invisible.

So what does all this really mean? Could Harry Potter’s invisibility cloak really exist? In the future, perhaps yes. Yet, there are even bigger implications of a possible invisibility cloak – good and bad. Using metamaterials to bend light waves, society could improve its security by placing ‘invisible’ policemen around each city. A country’s military could also benefit from such technology as tanks and airbases could be hidden from the human eye. However, such an invisibility cloak could also increase crime rate in the future as this technology could be further developed to bend sound and magnetic waves as well, allowing terrorists carrying guns or bombs to walk through metal detectors undetected. This could arouse an ethical debate over the use of metamaterials and invisibility cloaks. Yet, the debate can wait till the day researchers create the first cloak invisible to the human eye.


1. “HowStuffWorks “Metamaterials: Bending Light Waves”” HowStuffWorks “Science”Web. 07 Oct. 2011. <>.

2. “Researchers Create Functional Invisibility Cloak Using ‘Mirage Effect’ | Fox News.” Fox News – Breaking News Updates | Latest News Headlines | Photos & News Videos. Web. 07 Oct. 2011. <>.

3. “How Do ‘invisibility Cloaks’ Work?| Explore |” | Home. Web. 07 Oct. 2011. <>.

Stain-repellent Khakis??

Ever strolled into an outfit store and picked out a pair of khaki trousers from a rack that has a big red poster hanging from it with three simple words printed on it: “Stain-Repellent Fabric”? And you go thinking, “Yeah right!”

All of us have gone through the unpleasant experience of dropping drinks and foods on our clothes before and watching in distress at the giant stain that appears soon after. So, how can fabric be stain-repellent? It must simply be a marketing stunt? Incorrect. Welcome to the realm of nanotechnology.

On a basic level, nanotechnology is the manipulation of molecules in order to build structures starting from the molecular state. When working with nanotechnology, scientists work with structures from 1 nanometer to 100 nanometers. In order to understand how small that actually is, you can see below that a red blood cell is approximately 7000 nanometers across.The size of a red blood cell

Now, imagine working with particles seven hundred to seven THOUSAND times smaller – and we all have trouble putting a thread through the eye of a needle!

So how does the concept of nanotechnology have anything to do with stain-repellent fabrics? Working with structures so small allows textile manufacturers like Nano-Tex, to work with nano-sized particles and fibers that further enhance the quality of the fabrics. By using nano-sized fibers, also known as nanowhiskers, these manufacturers are able “to pack extra atoms” into the fabric atoms, which help repel liquids spilt on the surface of the fabrics.  Thus, the fabric is almost invulnerable to liquid as the tightly packed atoms cause the liquid to bead up and slide off the fabric rather than soak into the fabric.

Kool Aid beads up on Fabric

In this picture, red kool-aid is poured onto a pair of trousers and you can see that instead of soaking up into the fabric, the liquid is beading up.

Nanowhisker embedded in fabric

In order to embed the nanowhiskers into the fabric, as shown in the picture, the fabric is submerged into water filled with billions of nanowhiskers. As the water is heated and evaporated, the nanowhiskers bond chemically with the fabric. The nanowhiskers make the fabric hydrophobic, i.e. water-hating. Therefore, the implanting of nanowhiskers prevents the water from soaking into the fabric, and instead they act like “the fuzz on a kiwi” and create a cushion of air around the fabric, causing the liquid to bead up (due to surface tension of the liquid droplet) and roll off. Unfortunately, the chemical makeup of nanowhiskers is unavailable in the public domain and thus, it is not possible to demonstrate the bonding of cotton fabric (cellulose) to nanowhiskers.

So, it turns out that “stain-repellent” clothes are not just a marketing gimmick, but rather cutting-edge technology. However, nanotechnology is not limited to consumer-based products only. Research is ongoing in the field of medicine to produce delivery systems that can pinpoint and destroy viruses and cancers with laser-like accuracy rather than the collateral damage of chemotherapy today. In addition, work is ongoing to produce light-weight carbon materials many hundred times stronger than steel among other applications.

As nanotechnology advances, there are several unanswered questions. What is nanotechnology: 1nm to 100nm or just up to two-tenths of a nanometer? How long will it take before nanotechnology is useful from the mainstream perspective? Are we aware of all the possible deleterious effects of nanotechnology (stain-repellent fabrics), and are there any regulations to protect us from the same? One of the areas of research is increasing the human lifespan – will this be available to all or a prerogative of the rich only?

598 words.


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ITJ.” The Indian Textile Journal – Technology & Trade Info for Tomorrow’s Textile

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