What makes someone a great teacher is not just his/her skill in spreading knowledge but in creating a sustainable environment for this knowledge to thrive and perpetuate in the minds that it resides. Bearing in mind the impact they have on us, this series will delve into the lives and experiences, as well as the academic expertise of the professors of Indian Institute of Technology, Madras. Here, they open up about their specific contribution to their chosen subject and the personal growth they have witnessed over the years. Ramcharan Reddy pens his interaction with Dr Ashis Kumar Sen.

Bionote: Dr Ashis Kumar Sen is an Associate professor in the Department of Mechanical Engineering. He graduated with an undergraduate degree in Mechanical Engineering from NIT Rourkela and went on to pursue a master’s degree from IISc, Bangalore and subsequently a PhD from University of South Carolina (UoSC), with work experiences in several product development companies, in between years of his study. He also does research with his team of research scholars in the field of microfluidics with a major focus on Lab on a Chip (LOC) technology and Interfacial phenomena in fluids. He discusses his unique pursuits in the relatively new and booming field of Microfluidics and its Biomedical applications.

Walk us through your journey to IITM.

I did my B. Tech from NIT Rourkela and I was placed in an oil corporation. Then I attempted GATE in the first year after my graduation while working in that company. Later in the wake of my good scores in GATE and the seat in IISc which was too good to pass up, I joined IISc, Bangalore for a Master’s degree. After that, I got placed in a product development company. I was working on cooling solutions for electronics.

There was this one time where we were faced with the problem of developing a cooling solution for Intel Pentium Prescott (Pentium 4), without compromising noise and vibration control. It was challenging. You can always put a bulky fan or a big heat sink but an unnecessary increase in mass will cause unwanted noise and vibrations which is not desirable. It later hit me that this problem needs a greater thinking and understanding than what usual master’s graduate students could do. It also sparked an interest in me towards this field of science and I went ahead with doing a PhD at University of South Carolina.

I worked on microfluidics and I have worked on development of several micro devices for doing proteomic analysis (subjecting proteins to an electric field and calculating the amounts of proteins present from mass to charge ratio observed). After PhD, I again joined a product development company in the UK and also did some research in a local university first on the development of a microfluidic device for detection of bacteria in soil and then a micro flow cytometer for enumeration and detection of microparticles. But I had some commitments here in India and I moved back.

I never had this whole plan of 4+2+4 at the beginning of my B. Tech, it all just turned out so. But I knew that I would come back and do research in an IIT, partly because companies here didn’t have that much focus on research and it’s been 8 years now; all going great.

NIT-R vs IISc vs UOSC, tell us the biggest differences you noticed in the students and faculty.

One common thing is that there are definitely a lot of people driven by passion, be it research or teaching but the intensity is inevitably different. In NIT-R, the focus is more on undergraduate teaching whereas at IISc and UoSC there was more focus on research.

(Then we dug a little deeper into his field of study)

How did you take up Microfluidics and got set into this path you are on?

I came to know more about microfluidics when I was working for the company after my master’s, and micro-channeling was an upcoming field. New kind of electronic systems (MEMS) were coming up, so liquid cooling through micro-channeling was a hot field those days. Though I joined my PhD with this in mind, my field was not in cooling but in Biomed applications. I had an option for liquid cooling studies also. I did work on it parallelly with Biomed for some time, but then I chose Biomed. Though the applications are different the basic underlying physics was not very different.

Can you shed some more light on Microfluidics?

Microfluidics is an interdisciplinary field which requires knowledge of Fluid mechanics, Material sciences, Electronics, Communications, Biology and Chemistry. We have MSc. Biology graduates as project staff and I grasp a lot from them about Biosciences. I have also collaborated with professors from other departments for example, Electrical engineering and Chemistry. However, most people think it has a major involvement in Fluid mechanics which is not entirely true.

(When asked about the noticed fear of Fluid Mechanics among students and its effect on prospective students joining this field)

I think the heavily nonlinear equations such as Navier-Stokes equations and differential forms of conservation equations are at the root of this problem. Involvement of experiments in courses by making the students practically visualize the theory we teach in the class will help a lot in improving this scene. Even in the beginning when I first joined the institute, several students did not know much about the field of Microfluidics and were hesitant to join this research group, but now I send students back because of no left spots. There are actual PhD students who come specifically for Microfluidics at IITM even before writing the admission test. I could say we improved a lot.

Not only here but around the world too. This field has been around for more than a couple of decades but it has been evolving and picking up the real pace for the past few years.

(On the origins of this field)

Microfluidics received a revamp in its scope of study after a pioneer pointed out in a 1989 convention that Biology and Chemistry are going to be a major part of this field of study. Before that, anything and everything that involved fluids at a microscale were considered Microfluidics even though it didn’t have any connection with the microfluidics we know today whatsoever.

What are the applications of this field in particular?

A simple search will yield you that Microfluidics is giving remarkable results in the field of cell and DNA analysis using LOC technology. However, overshadowing the Biomedical applications seem, there is considerable research going on in micro-propulsion, electronics cooling and mechanical understanding of microfluidics. Just a breakthrough is all it needs. The real advantage of this micro-level study is the reduction of length scale and volume, and the new Physics it offers which ultimately facilitates new operations in science.

Can you elaborate on LOC – Lab On Chip?

LOC eliminates the tedious process of sending a sample to a lab and doing countless procedures on it with a small credit card shaped device which will just do all these processes then and there. Once it takes a sample, data can be retrieved from associated devices. Many feel that it’s more like a chip in a lab than lab on a chip because of the peripheral systems. (For example, instead of using a conventional lab scale centrifuge one could use a microfluidic device to separate plasma from whole blood, as a sample preparation unit thus facilitating optical detection of analytes in plasma). There are nevertheless successes like pregnancy test kit, dengue and thyroid detectors. Removing these external systems leads us to problems like “How does one manage the incoming or source of analyte channels; if not a pump, do a capillary tube? But we have no way of controlling capillary flow in-situ.” We also need simple mechanisms for detections like the colour change, not a big multimeter box.

Can you elaborate more on the focus of this research station at IITM on Microfluidics?

Interfacial phenomenon is our major interest and we hope to produce something for the society. We also look at diverse problems. It is quite the Shrek.

Droplet microfluidics: Aqueous drops in oil phases are in the order of Pico liters. These droplets can be controlled to capture cells and chemicals to the droplet and these droplets can be streamlined and thus cells can be monitored.

Magneto fluidics is one of the upcoming fields. We heard about it at a conference and began working. All we want is to manipulate these drops. Ferrofluids can be oil based and can be used to manipulate aqueous droplets. Some magnetic beads are being used to detect cancerous cells.

Elastocapillarity: Channels can be designed without designing a conduit or path for flow. We have created a flat membrane of a particular polymeric material is laid down and drops are added onto it. Due to the presence of the droplet, an internal pressure difference is created and the film folds up itself and the drop moves through it. This field is called elastic membrane fluidics/ elasto-capillary studies. It is a very upcoming field and only a handful of people are doing it. Pioneers say that we don’t have control on capillary flow, it only happens according to the geometry. Magnetic field is also being used to control the capillary meniscus.

A differential radius of curvature causes the drop to move on its own because of Laplace pressure difference.

Wetting: We have done diverse work on wetting. We tried to create a super hydrophobic surface. Candle soot on a glass surface is an unstable superhydrophobic surface. We have used candle sooting of a PDMS coated glass slide to prepare stable superhydrophobic surface. A contact angle of 160o-180o is being noticed in these cases. We have also shown that the superhydrophobic surface can be converted into a superhydrophilic surface and vice versa.

(He showed me several simulations of fluid flows based with external materials and droplet formations.)

Based on droplet size encapsulating a cell, the droplets encapsulating cells and empty droplets can be sorted out.

Coalescence of aqueous drops into a water stream under an electric field for demulsification was demonstrated.

Acoustics: Blood and plasma are separated. With the interaction of the waves, particles with different natural frequencies (control flow) get subjected to a different kind of force and thus accumulate in different streams. Some waves have shown to create vortices in fluids. Only a few groups around the world are working on it. Fluid flow can also be tracked when is subjected to acoustic waves.

We developed a device to count emulsions by using scattering light experiments and the number of peaks and size of peaks to tell the sizes and number of the emulsions.

We also did something for capillary-based plasma and blood separation system and also developing a subsequent testing system for dengue detection. It is a static source, use and throw device. It makes blood and plasma streams adjacent unlike the previous case of parallel streams.

Collaboration with Apollo Hospital: As part of a project funded by IMPRINT and IITM, we collaborated with a cardiothoracic surgeon about these applications in the medical field. It was on Post operation defects recognition techniques, studying on causes of death of patients after a fine surgery. Based on a few proposed hypotheses, it was taken that some white blood cells (WBC) attack the organs itself and the patients die due to multi-organ failure. He noticed that there are differences in contents of Hydrogen Sulphide (H2S) and three other gases (NOx types) too. They have done a lot of clinical trials for this but testing had to been done using microfluidics then and there, as taking it to a lab makes the gases escape soon. Tests like these really give hope in case of unsolvable cases.

We developed a device for this, for which we even stayed in the hospital. Sepsis is also one of the diseases that needs micro attention The field is booming and we have made some real progress. Few researchers in China have published about this but, they had a different approach. So it would be great if a single device that can measure all the gases could be invented.

What is going to be the next big step in Microfluidics?

I think it is creating artificial organs such as heart, lever, lungs etc.- Organ on Chip. These microfluidic devices would mimic the functions of organs. Some devices are being made to replicate liver and the organs are to be developed. It would take time to realize to build these artificial organs. However, once developed, this would have tremendous effect on various other fields such as drug development etc. which currently has a very large cycle time. Seeing through the eyes of science, isn’t making lungs easy? It doesn’t involve any complicated reactions as it is just a mixing chamber. But it’s of great difficulty as the chip should accurately represent the structure as well as the functions of organs in the body. All these difficulties need to be crossed.

What do you like more, teaching or mentoring researchers?

I like teaching. I like interacting with students. Good students are those from whom you learn. Research scholars we get are reasonably good. The quality of incoming students is improving each year. If we can help them reach the correct kind of problem to solve, they can do a lot. Though the minimum threshold for intelligence is needed, willingness, sincerity and perseverance are very much needed for a research scholar. We can mend them to do great work by proper mentoring. During mentoring, either be PhD or DD students, you have to observe and notice what they would really thrive at and mend them in that direction. Seeing them transform from a beginner to the peaking of their thought process when they leave is quite satisfying.

How does teaching students of different years affect your preparation?

Teaching 5000/6000 level courses is not so different compared to 1100 ones. I try to do my best in delivering. But sometimes a large class can be too hard to manage, irrespective of the year of study.

How did you choose IITM among all the IITs?

Me choosing IITM was serendipity. When I sent applications to all IITs, only IITM replied with a visiting offer and later a permanent offer. I went through all the vetting processes and accepted the offer. I also got a grant immediately. Also, I had a lot of support and this place was good. So, I stuck with my choice, even though I received callbacks from other IITs after joining here. IIT KGP is near my home Bhubaneswar. I could have chosen that but I stuck with my commitment.

What do you do in the Institute during your free time?

I like walking in the morning. I watch movies in OAT with family. I also go to Gurunath, Zaitoon and the New Academic building cafe. I love walking, especially with this new stadium. IITM is quite lively, except for the occasional, inevitable, monkey attacks.

What are your other hobbies and interests?

I used to play cricket during my B. Tech and after a brief hiatus, I restarted with the friendly faculty vs student match organized by MEA last year.

What would you be doing if you weren’t in academia?

I like growing plants and living by nature. Maybe, I would have been doing that.

One final quote for our students?

I think the students should ask what they really want to do, beyond the whims. Maybe something that is not practically pleasant or momentary. More meaningful decisions are expected from PhD students as they are more mature than undergrads. Ask yourself what you want to do really. Search for bliss and resist whims. Students have a lot of potential but they have to channel it in the right path. You achieve the real satisfaction by achieving a greater accomplishment rather than with the pleasures of temporary distractions. They should have the courage to overcome such distractions.












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