Akhlesh Lakhtakia

Akhlesh LakhtakiaAkhlesh Lakhtakia is the recipient of Sigma Xi's 2016 Walston Chubb Award for Innovation. He was born in Lucknow, India, and obtained a Master of Science and Doctor of Philosophy degrees in Electrical Engineering from the University of Utah, Salt Lake City in 1981 and 1983, respectively. He went on to earn a Doctor of Science degree in Electronics Engineering from the Banaras Hindu University in 2006. In 1983, he joined the faculty of the Pennsylvania State University, where he is currently the Charles Godfrey Binder (Endowed) Professor of Engineering Science and Mechanics. He also serves as a Professor in the Graduate Program in Materials. 

His current research interests lie in the electromagnetics of complex materials including chiral and bianisotropic materials, sculptured thin films, chiral nanotubes, nanoengineered metamaterials, surface multiplasmonics, bioreplication, bone nano-refacing, and forensic science. His research accomplishments have been discussed on CNN and in a NOVA movie. 

Dr. Lakhtakia has published more than 800 journal articles; has contributed 27 chapters to research books and encyclopedias; has edited, co-edited, authored or co-authored 18 books and 17 conference proceedings; and was the first editor-in-chief (2007-2013) of the online Journal of Nanophotonics  published by SPIE. He serves as an international lecturer for the International Commission for Optics, SPIE, and the Optical Society of America.

Dr. Lakhtakia is a Fellow of the Optical Society of America, SPIE (1996), the UK Institute of Physics, the American Association for the Advancement of Science, the American Physical Society, and the IEEE. 



Heather Thorstensen: Hello. My name is Heather Thorstensen and I'm the manager of communications for Sigma Xi, the Scientific Research Society. Today I am speaking with Akhlesh Lakhtakia who is the Charles Godfrey Binder Professor of Engineering Science and Mechanics at Pennsylvania State University. He is Sigma Xi's 2016 Walston Chubb Award For Innovation recipient.

This award is presented to honor and promote creativity in science and engineering. It carries a $4,000 honorarium and invitation to give the Walston Chubb Award Lecture at Sigma Xi's Annual Meeting. The 2016 Annual Meeting will be November 10th through 13th in Atlanta, Georgia, and you can find more information about that meeting on Sigma Xi's website at www.SigmaXi.org. I'm going to start by asking Professor Lakhtakia to explain what sculptured thin films are, which is a technology that he's developed.

Akhlesh Lakhtakia: Hi. Thank you, Heather. Imagine that you have a lot of hair altogether. Something like spaghetti, except that they're all lined up, they're all the same, they're all identical to each other, okay? They all have the same shape and they are stuck, not on your head of course, but on some flat surface. This is a model of a sculptured thin film. The diameter of each one of those hairs can be very small. The smallest that we have made are as much as small as about 50 nanometers. One nanometer is about a millionth in diameter of your normal hair.

When you make a material of this kind then you can classify it as a nanomaterial because the material has essentially physics occurring in the nanometer regime, in the nanometer size level. Now these materials turn out to be optically very useful because you can guide light through them in a way that you have designed beforehand. You can change the spectrum of light that passes through and you can change a property: polarization.

Polarization of light is something that you appreciate when you put on those wonderful glasses that make you look like James Bond. Right? Okay, you can also use them for a variety of other optical purposes.

Thorstensen: Okay. We'll talk more about that in a little bit. Could you explain how you came up with the idea of sculptured thin films?

Lakhtakia: Well, that's an interesting story. My daughter was about five or six years old, six years old or so, and I went to pick her up from a birthday party at another child's home. While I was waiting for her to get dressed I happened to see a specimen of a mineral lying on a table. I picked it up and I was immediately floored. I had never seen anything like this.

Now here is an example of that kind of a crystal [shows the audience a crystal]. You can see this way you can probably see through. You can probably see me through the crystal. If I rotate it by 90 degrees then you can't. The reason for that is this crystal, this material, is made up of long fibers that are all glued together. If you look through the fibers you can see on the other side. If you look at right angles of the fiber axis then you can't. Okay?

I was just amazed to see that a rock like this or a mineral like this exists in nature. I asked the mother of the child whose birthday party it was what was it and she said to me, "This is called ulexite and it is popularly called TV rock at the rocks and minerals stores." I came back and the next day I called up a colleague of mine who used to make thin films. His name is Russ Messier. I said, "Russ, can a material like this be made in a laboratory?"

He said, "Yes, of course." He came over the next day and showed me various kinds of papers and scanning electron microscope pictures. Yes, this could be made. I said, "You know Russ, can we do something like this? While this film is being deposited, which has this fibrous structure, can we rotate the substrate on which it is being deposited?" He said, "It should be possible." That is how sculptured thin films were born.

Thorstensen: Can you explain what it is about the rotation? It actually makes you able to design the shape?

Lakhtakia: Well, when you can have substrate rotation, then light, when it passes through a collection of fibers like this, light has a property called polarization. Polarization has to also rotate along with the fibers. Now this property changes with the frequency of light. Light of some frequencies can rotate, light of other frequencies cannot rotate.

Also, light itself may have a rotational polarization. In which case if it has the same type of a rotation as the fiber has, then it passes through. If it has the opposite type of rotation it does not pass through. Okay? These things of course, in order to understand them you have to solve equations called Maxwell’s equations. That is of course a big theoretical study all behind it. It can all be done and now we have seen that we can actually make these things in a lab in a way that we want them to function optically.

Thorstensen: These films can have applications for optical devices, that is one of the areas. Let's start by talking about just the optical device application potentials.

Lakhtakia: Well, they can be used as filters. They will allow light of a certain frequency range to pass through, but not of other ranges. As an example, human eyes are tuned to—I will not use the word frequency now. I use the word wavelength. That is easier to understand—wavelength of light that we are sensitive to light between 400 and 700 nanometers.

Some insects can see light below 400 nanometers or above 400 nanometers. Above 700 nanometers, I'm sorry. Light can come with a certain wavelength into this kind of a material and then when it leaves it may have some other wavelength range. In this way we can filter out light which will not be allowed to pass and we will allow light only of a certain wavelength range to pass through.

That's one use. 

The second use is of polarization. The electric field vector that comes with light vibrates. It can vibrate like this [in a straight line, back and forth], that's called linear polarization. This also is linear polarization. Or it can vibrate like this. This is, let me see here, like this. This is circular polarization. There are two types of circular polarization. One is like this. The other is like this.

Left handed and right handed, okay? Different types. We can, by designing the fiber shapes, we can allow light of a certain polarization to pass through and knock off the other type of polarization. In other words, we can use this to have filters which are filters of wavelength and are filters of polarization.

Thorstensen: How would those filters of wavelength polarization be used? Who would be wanting to use that kind of filter?

Lakhtakia: Those kinds of filters are used all the time. For example you use them in your cameras when you put filters on your camera to change the characteristics of light, right? Or you use them in your glasses when you want to reduce the intensity of light outside. Those polarized lenses. Or you use them in 3D cinemas. The two lenses in 3D, when you watch a 3D movie, one of them rotates light this way and the other one rotates light this way.

That's why you don't get both signals mixed except in your brain, of course where you want them to be mixed. Yes, so that has numerous, numerous uses. They also use it in spectroscopy when you want to look at the characteristics of materials. For example when you want to identify what kind of material is found for example at a crime scene, as an example. You look at it spectroscopically. If you don't believe me follow Abby [Sciuto] on NCIS.

Thorstensen: Okay. Then can you talk about how you've also been applying the sculptured thin films to other areas like solar cells?

Lakhtakia: Sculptured thin films for solar cells are sort of in a roundabout way. One of the things that I had noticed as a child was that flies are difficult to catch. The reason is that they can see you from behind, when your hand comes from behind they can see you. You have to be very, very fast to be able to capture a fly. I reckoned years ago that there must be something about the eyes of a fly that allow it to see from a very wide sector, in a very wide sector.

I thought it would be a good idea to somehow replicate the structure of the eye of a fly. One of my graduate students, he caught some flies and plucked out the eyes after killing the flies and then he deposited these thin films. Not very thick, I would say about 500 nanometers thick films of this kind. They were made of nickel. When the eye was separated from the film, the film was left, nickel film was left as the mold. Then we would press it on different other types of materials and make copies of the eyes.

This was the start of my research on a technique called bioreplication. A couple of years later a colleague of mine said, "Can we somehow bioreplicate the surface, the upper surface of an emerald ash borer. Female ash borers are seen by male ash borers. They're actually seen. They're not sensed by some chemical.”

If therefore we could replace a female ash borer by a decoy that looks like a female ash borer with a male, then in that case we could disrupt the mating cycle. At least that was the idea. We did the same thing with a female emerald ash borer. We coated its top with a nickel film, nickel sculptured thin film and the result was that we got a mold.

Then using that mold we made many hundreds of copies of that fly, of that particular emerald ash borer, which were then deployed in experiments by entomologists. They reported that the decoys that we had made were 40% better than dead females in attracting males. This is certainly a success story because just last year my group published a paper in which we actually were able to make ten copies at the same time. In fact the technique is such that you can make hundreds, maybe even thousands of copies at the same time. This is a bioreplication technique that is industrially scalable.

Thorstensen: Okay. Now you're moving into an area of making items that have multi-functionality with this, with the sculptured thin films. Could you talk about that?

Lakhtakia: Well, sculptured thin films have fibers that have a diameter of 50, 60, 100 nanometers or so. If we were to increase the diameter to 5,000 nanometers, then the films would acquire totally different properties. We make those films of a polymer called Parylene C. This a polymer that is bio-inert which means that it does not have, it will not impede biological functions.

We make these films. We call them micro-fibrous films. On top of these micro-fibrous films we have seen that cells can grow and eventually form a tissue. They have definitely biomedical qualities which can be used at a later stage perhaps for transplants. 

Another thing that we do with them is to determine if they have acoustic properties. In fact that is what one of my graduate students is doing right now.

We have found that these can be used as ultrasonic filters at frequencies that range from a few megahertz to about 160, 170 megahertz. At the same time, exactly the same material without any change can be used for optics, but at a much lower frequency than we can see with our own eyes. That is called a terahertz regime. The film that will have acoustic properties or ultrasonic properties in the megahertz regime has special properties that make it very attractive electromagnetically in the terahertz regime.

Thorstensen: Sculptured thin films also have potential with forensic science. Could you talk about that application?

Lakhtakia: That's a fantastic application. I like to watch forensic shows on TV. Some years ago I was thinking about, it's more like nine years ago now. Okay, I was thinking about using the sculptured thin films for sensing toxic materials, except I don't know anything about toxic materials. I had a colleague here, Bob Shaler at Penn State. He is a forensic scientist.

He didn't tell me too much about toxicology, but he said to me, "Can you find a way to lift fingerprints from surfaces which are most likely to have fingerprints at crime scenes, but we cannot see them?" I said, "Well, the one thing that I can think of is to take a specimen from a crime scene of that kind and deposit a sculptured thin film on top."

The reason why I think we should be able to see it is that the sculptured thin films would be formed on top of the fingerprint. It would not disturb the fingerprint at all by itself. That's exactly what happened. He gave me a specimen and I deposited a sculptured thin film on top in my laboratory. Yup, the fingerprint was as clear as it could be. It could be very easily seen by a fingerprint examiner and then classified, identified for identification purposes.

For several years then we looked at various types of materials like sandwich bags and garbage bags, white trash bags and black trash bags and knife handles and cartridge casings and wood of different types, hard plastics and on some of these existing techniques would work to identify fingerprints. On some of these existing techniques would not work very well or not at all.

For example, on cartridge casings: we were able to deposit sculptured thin films on top and these films are anywhere from 50 to 1,000 nanometers in thickness depending on the type of material. Some of these films are made of gold. Others of nickel, still others of a material called chalcogenide glass, germanium oxide. Various types of materials.

These films could then be seen. Now as I said earlier, the sculptured thin film is formed on top of a fingerprint so whatever is inside the fingerprint is entombed by the sculptured thin film and is therefore preserved. Whenever you touch something you are likely to leave behind one or two cells. Cells contain DNA and DNA can be identified as yours or of somebody else's depending on whose it is.

Fingerprints that have been visualized using sculptured thin film technology have entombed DNA. Another colleague of mine, Reena Roy and I, we have been working now for about three years on this, we have been able to show that we can take a fingerprint, coat it with sculptured thin films, keep it in moist air or dry air or high temperature or low temperature, cold or high heat, when it is cold or when it is hot for various periods of time, as much as six weeks.

Then we can still recover DNA from the fingerprint that had been coated with the sculptured thin film and identify it. This way we have a dual identification scheme, first of all the fingerprint itself visualized with the sculptured thin film can identify, can be used to identify, the person whose fingerprint it is. Secondly, the entombed cells containing DNA can then be analyzed for the DNA content and be matched to various people and determine the identity of the person.

Thorstensen: That's very interesting. It's interesting to hear you talk about how you've come up with these ideas just based off of your own life experiences. You saw this crystal when you were picking up your daughter. You thought about how else it could be, how that concept could be used. You saw the flies growing up in India so you were thinking about how that could be applied to solar technology. Since this award is for creativity, would you say that you've always had that type of taking from real life and using it into your own field in your life?

Lakhtakia: I would like to think so. I'm not quite so sure. Maybe at one time I wasn’t, I didn't look. I should tell you a few years ago I was asked at a conference to talk about innovation. I said that practically anybody can become innovative if they do three things, three very simple things. The first is they should look. Most of us walk around with our eyes shut most of the times.

We do not look. I certainly have found that the more I look the more I find. The second thing we have to do is to organize. Whatever you look, you have to say okay, well this is this kind of a phenomenon, or that kind of a phenomenon, right? You then have to put it in some sort or, in a set of pigeonholes, okay? The third thing that you then do is you learn how to make those pigeonholes, how to classify.

If you can look and if you can organize and if you can learn to organize, then gradually I think you begin to see patterns. Once you start seeing patterns, then you can formulate hypotheses. Then you can test them. I think that is all there is, the secret of innovation.

Thorstensen: It seems that also has helped you to be innovative in order to know who it is to go to when your own discipline is at the end of your own knowledge and then you know who to take it to. How is that you've been able to build those connections?

Lakhtakia: Learn. Meet people. Read. Read the Scientific American. Read the American Scientist. Go to a book store. Watch television shows on nature. Watch television shows on science. Listen to NPR reports. They often have fantastic reports on science. Basically, keep your senses fully engaged and find the right people to collaborate with, so that your ideas would come to fruition is then not a difficult job.

I was blessed by being at Penn State which has a wonderful, I have a wonderful collection of colleagues, but I don't have to be confined to Penn State. This is the age of Internet. I can find experts anywhere in the world.

Thorstensen: Great. Well, thank you so much for sharing your research with us today and congratulations on your Sigma Xi award.

Lakhtakia: Thank you, Heather. Thank you very much. It was a pleasure to talk to you.

Thorstensen: Goodbye.

Lakhtakia: Bye bye.