Thursday, February 12, 2015

Nanolaser cancer therapy - A new spaser powered phothermal cell destruction method

Encircling tumors with a phalanx of miniature nanolaser could offer a new way to battle cancer,we propose as a new method of cancer treatment. Technically, the proposed device isn’t really a laser at all, but a spaser, with surface plasmons rather than light undergoing amplification.

Earlier last year, we proposed a different design, using graphene and carbon nanotubes. In this setup, a carbon nanotube would absorb the energy from a separate laser source and transfer it to the surface plasmons of a nearby nanoflake of graphene, creating the spaser effect. Pumping the spaser with 1200-nanometer light would cause it to output light at 1700 nm.  

The nanotubes and graphene flakes could have antibodies or ligands attached to them that would draw them to the tumor. Once at the tumor, they’d self-assemble into a cluster of spasers.“You surround cancer cells with very tiny lasers, instead of nanoparticles,”

An external laser producing light between 1000 and 1350 nm could penetrate several centimeters of human tissue and act as a power source for the spaser cluster. The spasers would then deliver a concentrated blast of heat to the cancer cells. At the same time, the nanotubes could be designed to carry drugs to their target, hitting the tumor with a one-two punch.

Discovery article ,  IEEE spectrum article

Graphene- carbon nanotube spaser nanolaser introduced

We have been able to design the world's first 'spaser' - a nanoscale laser - made out of graphene and carbon. A spaser (surface plasmon amplication by stimulated emission of radiation) is effectively a nanoscale laser, or a nanonlaser. It has been touted as the future of optical computers and technologies. It could enable ‘nanophotonic’ circuitry, extremely small circuits far tinier than anything available today. This could usher in many technological advances including microchips hundred times more powerful than anything we have today.

'Our device would be comprised of a graphene resonator and a carbon nanotube gain element.'

'The use of carbon means our spaser would be more robust and flexible, would operate at high temperatures, and be eco-friendly'

See article for more information

Wednesday, April 10, 2013

Spasers (nanolasers) - for the continuation of Moore's law

           The emerging era of nanoplasmonics is expected to improve the speed and efficiency of optical devices by facilitating miniaturization beyond the limitations of conventional optoelectronics. It is seen that, as the technology matures during the last few decades, the utility and advantages of ‘electronics’ can be surpassed in certain instances by using ‘photons’. However, the used wavelength in most of these technologies is around the order of micrometers, thus the fundamental diffraction limit has intervened to constrain the advantages of scaling below the subwavelength stage. The solution is to use a hybrid particle state  between electrons and photons which is known as ‘surface plasmon’ to operate in the nanoscale. The SPASER (Surface Plasmon Amplification by Stimulated Emission of Radiation), is the active nanoplasmonic device that can generate surface plasmons and amplify them similar to the lasers.

A video explaining the principle of operation of spasers:


Graphic credits :

3.Bergman et al., Phys. Rev. Lett., 90:027402, Jan 2003
4.Chang et al., Opt. Express, 16(14):10580–10595Jul 2008
5.Lisyansky et al., Phys. Rev. B, 84(15):153409, 2011
6.Zheludev et al., Nat.Photonics,  2(6):351–354, 2008
7. Seidel et al.  Phys. Rev. Lett., 94:177401, May 2005
8. Noginov et al., Nature, 460(7259):1110–1112, 2009

Friday, June 10, 2011

Can there be both 'rational and irrational' numbers ?

Everyone knows, from the school, that square root 2 is irrational . I still remember the fashionable way in which my school teacher proved it. (for those who do not remember ). As all know, an irrational number cannot be written as a/b where a and b are integers. We know following facts which are proven in fashion in real analysis.
1. Any real number is rational or irrational
2. There are infinitely rational and irrational numbers
3. There are infinitely integers
 'Can we say a given number is rational or irrational ?'. (If it is given in decimal points, number is rational for sure) . What I really mean is if I marked a random number on number line (see how irrational numbers are marked on number line at, who on the earth can say it is rational or irrational ? Since there are infinitely integers it can be a ratio of any two of them. Or since almost all the real numbers are transcendental (  and all transcendental numbers are irrational, there is a higher probability of randomly marked number is being irrational. 
Therefore until being confirmed (or observed) we cannot comment about the rationality of the number. But we can give a probability distribution for the rationality of the randomly marked number. 
According to quantum mechanics, we can say this number is in superposition of states.  i.e. the number is both rational and irrational. Described probability distribution is the wave function. 

Saturday, February 12, 2011

2011 -2020 a decisive decade for mankind

    2011 is the first year of the 202nd decade which is to be end in 2020. This decade is going to be one of the decisive decades in human history due to many scientific, economic and political reasons. We had something similar decade in 1940-1950 where initial steps to the digital revolution kept with the invention of the transistor and Von Neumann and Alan Turing publishing their papers on stored program computers (First Draft of a Report on the EDVAC by Neumann and Automatic Computing Engine by Turing), first nuclear bomb was produced and world power was shifted to US and Russia.
   This decade is similar because by 2020, we are approaching the end of Moore's law (doubling the performance of semiconductor fabrications in every other year ) , there will be plans replace modern computing with quantum computing, reaching the end of the era of fossil fuels and will be having earth with an unpredictable climate patterns.

End of Moore's law and quantum computing

    While we are making the processors smaller and smaller, there is a limit that behavior gets unpredictable according to the laws of quantum mechanics. Then we will face a quantum leap or saturation. But recent developments in quantum computing and nanotechnology say we are not that unfortunate to face a saturation and coming to a dead end. However this will be decided by 2020. If we are going to replace modern computing by quantum computing, programming concepts will entirely be changed. New languages will replace C, C++ , Java etc.

End of fossil fuels

    Despite the end of fossil fuels is not a proven fact, most nations have plans to replace fossil fuels by alternative sources in 2020. Sweden have plans to 100% fossil fuel eliminations in some regions and most other nations have plans cut off the fossil fuel usage by some percentage. Since we are reaching the end of the resource, finding alternatives is a must and otherwise it'll be serious energy crisis. This will be decided by 2020 and there we will be able to say whether we have to travel by carts or not.

Climate change

     Since no proper agreement to limit global greenhouse gases came effective and US and China have not shown a commendable commitment, unpredictable climate patterns may occur by 2020. Even in this year, 2011 we have seen much of them all over the world. (Australia, Brasil, China etc.) . We will probably  start experiencing the effects of global warming in 2020. There we will see the fate of mankind.

P.S. : New world order

    Although shifting the world power from US to China may not happen there will be many world super powers unlike we had in last century. Anyway this matter is a topic of political scientists and does not suit the scope of this blog :)

image source :

Thursday, December 9, 2010

Science, Religion and Technology

Science, religion and technology  have different objectives as,

Science - understanding the nature (or universe)
Religion-  understanding nature and teach human the good and bad
Technology - make human's life easy

Their is no doubt that religions' all time mission on teaching human the good and bad is successful though many wars (in medieval ages and after in Europe, Crusades etc.  ) and some terrorist activities (at present) have direct relationships with religions. But religion was a crucial factor in civilization. One might argue that UN's "The Universal Declaration of Human Rights" ( can replace religion. But we've become civilized enough to prepare that 'universal whatever' as a result of religion. When talking about 'good and bad' ,all regions are similar. But the interesting part is religion's other objective 'understanding the nature' which overlaps with science.

Let's consider some concepts in religion

After life : All major religions (Christianity, Islam, Hinduism and Buddhism) possess some sort of an after life. In Hinduism and Buddhism one can be born again as human or animal. There is also a little difference between two regions. But for this discussion we ignore that. In other two regions human will be born in heaven or hell (different words may used )

Neither proven nor disproved scientifically

God/s : All 3 other religions except Buddhism teach that universe is created, maintained by God. In Hinduism, it is quiet different from other two. However the important thing is,

Neither existence nor non-existence of God is scientifically proven.

Even Einstein had talked many times about God. (God doesn't play dice). In his 'The Grand Design', Hawkings has some other thoughts. There are many famous questions of God. "What is god ?" , "Where does he stay ?" etc.

In addition to after life and god, there are many other concepts as well. But the important thing to notice is incapability of science to prove or disprove the concepts in religion. Does it imply that human still need religion ?

Current trend seem to be the technology which doesn't have problems with religion. Technology is to make our life easier and it doesn't need to find answers to unnecessary (?) questions. It only concerns "How to get a thing done ?" (programming, networking etc.) But there will be a day that technology needs go deeper in understanding  nature. We'll be able to find the answers of religion that day.

Acknowledgement for image source :

Monday, September 27, 2010

Using pattern recognition techniques for controlling dengue epidemic in Sri Lanka

Dengue epidemic has become a threat to Sri Lanka with a fast spread all over the country. The National Dengue Prevention Unit of the Ministry of Health, Sri Lanka has reported 30,607 cases of dengue and 221 deaths during January-September, 2010 . Situation is same for many other countries as well.  The only way to get rid of this danger is the extinction of the cause-mosquitoes.

The lot of money which is spent for the prevention of this epidemic, can be optimized and maximum results can be gain if the pattern of the dengue vector-Aedes aegypti spread can be properly identified. Countries such as Singapore, USA and Cuba has used GIS (Geo Information Systems),statistical analysis and sensor network technologies to overcome this issue.

Currently, the foliole community ( works on a pattern recognition technique based on fuzzy neural networks and k-means clustering. The neuro fuzzy system is used to estimate the influence of prominent factors affecting the spread of dengue vector, Aedes aegypti - precipitation, temperature, humidity and urbanization. Other socio-economic facts such as education of the people and poverty can also be considered. Meanwhile training data is prepared using k-means clustering for reported dengue cases.

Read the full article here :

Saturday, July 24, 2010

Is Paul the wave function ?

       Wave function is known as the mathematical model that used to calculate the probabilities of an observable. As an example wave function of an electron, Ψ(x,y,z) provides us the probabilities of finding it at the position x,y,z (actually modulus of squared wave function gives the probability) after the observation.
       The phrase "after the observation" is very important in quantum mechanics. As an instance lets take the Schrödinger's cat. There is a cat inside a covered box and a gun is pointed to the cat. Triggering the gun is depended on a random event. Mechanism is gun will be triggered if a particular radiation happens within the period of the test. Hence there is a non-zero probability for both emission and non-emission. According to quantum mechanics, system is under quantum superposition until the observation is made. That is triggering and not-triggering at the same time which leads to the conclusion that cat is both dead and alive until it is observed.
      When the observation is made, we can only see only one state, dead or alive. This is known as 'wave function collapsing'. From the superposition, it comes to a single state at the observation.
      Lets go to the Paul's case. Lets assume the Germany vs Spain match is isolated so that quantum decoherance (avoidance of quantum superposition due to interaction/entanglement with environment) is avoided and no one observes the match. So match is in the superposition state of both teams are qualified for finals. Then we call our friend Paul, and give him the flags. He selects Spain and becomes a traitor.
      Now, what happens ? we don't know the results of the match. But with the record of the Paul, we decide, chance of poor Germans to be in finals is 10% and 90% for spain. Isn't this the wave function ?
      Then we go to Durban and open the gates of the ground to collapse the wave function. What we see is the verification of Paul's wave function...

Thursday, June 3, 2010

Research paper based on ninithi published

           Research paper based on the visualization part of ninithi was published at the "4th asia international conference on mathematical modelling and simulation" (AMS2010), Kota Kinabalu, Malaysia. Paper was titled as "3D modelling of carbon allotropes used in nanotechnology".
          Research paper is available on IEEE Xplore
          If you want more details about the paper please drop me an email to

Abstract :-
         Graphene, Carbon nanoribbons, Carbon nanotubes and Fullerene (Buckyball) are allotropes of carbon which are widely used in Nanotechnology research due to their remarkable properties. Electrical and mechanical properties of those allotropes vary with their molecular geometry. Theoretically, an infinite number of such geometries do exist and it is impossible to physically prepare samples of all of them in the real world. This paper is based on modeling the atomic structures of those carbon allotropes with all the molecular geometries in 3D space, given variable user inputs to select the geometry, and customizing the view varying the angle and colours. Equations to derive the coordinates of the atoms, algorithms to derive the orientation of the bonds of the molecular structures and the manner in which the algorithms are implemented using java3D are described in this paper. Successful results were obtained after the implementation of the algorithms which are illustrated with few screenshots at the end.

Friday, April 30, 2010

ninithi released

         ninithi which is a free and opensource modelling software, can be used to visualize and analyze carbon allotropes used in nanotechnology. You can generate 3-D visualization of Carbon nanotubes, Fullerenes, Graphene and Carbon nanoribbons and analyze the band structures of nanotubes and graphene.
         For more information visit and download the software free.