Engineering futuristic fabrics for personal thermal comfort

Published! is a series of chats with women in science highlighting their publications as leading authors. If you know someone who has recently published a scientific manuscript who would like to chat with me, you can get in touch via Twitter @laurenpoppi or email <lauren.poppi@rutgers.edu>.

Kony Chatterjee is a PhD Candidate from North Carolina State University and Wilson College of Textiles. Kony recently published a paper as first author, titled “In-plane thermoelectric properties of flexible and room temperature doped carbon nanotube films”, in the journal ACS Applied Energy Materials. You can read the article here. We chatted about the nitty gritty of testing new materials, why we should blow the dust off that old Chemistry textbook, and how familial support could be a key factor in the success of many women scientists moving forward.

How did this research paper come about? What was the motivation behind characterizing these carbon nanotube films, and can you explain to us non-material scientists what carbon nanotubes are and what they can be used for?

I’ll start with what carbon nanotubes are, and that will explain the motivation too. Carbon nanotubes are these really, really, really tiny tubes. Their diameters [can be] less than 100 nanometers. If you take a flat sheet of graphene, which is kind of like the same material that your pencil lead is, but your lead is graphite actually. If you just took one sheet of that graphite, that becomes graphene. You just roll it up, like you would a sheet of paper into a cylinder, that’s what a carbon nanotube is. So of course, graphene and carbon nanotubes go hand-in-hand in having a lot of interesting properties. People must hear about CNTs (carbon nanotubes) all the time, and that’s because they have very good (what we call) ‘transport properties’. They move electrons within themselves very well, so they conduct electricity really well. They can also move heat really well. So that’s why a lot of material scientists are focussing on trying to use these materials, CNTs and graphene, for many applications. This goes even beyond material science and biology.

My overall PhD research project is on thermoelectric devices. Basically, I’m developing a fabric that can provide next-to-skin heating and cooling. So, a big aspect of this fabric is – what materials can we use to provide that next-to-skin heating and cooling, and actively provide some form of thermal comfort to the wearer? Carbon nanotubes are promising materials for that, so that’s why we need to characterize the material and then put it in a fabric.

 

Does that mean that you could, in theory, have a jacket that is really thin and lightweight but heats your skin during the winter??

Yeah exactly (laughs). It’s funny… if you talk to someone in North Carolina they will say “do you mean a fabric that could cool you in the summer!?” (laughs)

It’s always so interesting how people ask these questions because thermal comfort is so personal. We all suffer from different things, some of us feel too hot, some feel too cold. The overall research is asking if we can add different patches on the fabric which can provide localized heating and cooling to you, so that mentally you feel cooler. There are certain parts of the body, where you can feel your pulse strongly, like your neck, your forehead, your wrist. If you provide even one or two degrees Celsius of cooling in these strategic locations, your mind, and to some extent your body, will feel much colder, or warmer, depending on the [design and use].

 

That makes sense. Growing up in Australia, when it was over 40°C (~100°F), our school teacher would tell us to go put our wrists under running cool water. Though my first thought for your material was for the brutal New York winter. Where can I invest? (laughs)

Tell us a bit about the process behind this paper, from collecting and analyzing the data, to preparing the manuscript. Was the writing finalized during the COVID-19 shutdown?

I’ve been doing this research since 2017, but yes, I would say that a lot of the finalization and editing of the paper was during the COVID-19 shutdown. The data collection literally ended for me maybe two weeks before shutdown. So, I had just about finished collecting data at that time.

The process of the paper was sort-of like this: First, I tested a lot of different materials, not just carbon nanotubes, but then narrowed down to carbon nanotubes because they had good properties. Then, I realized that there was a certain aspect of these carbon nanotubes, highlighted in the article title, which is ‘in-plane properties’. So, properties along the length of the film. That hadn’t been reported that well previously. I realized we had this opportunity to report all the properties, in-plane (in the same direction). Most people would report the thermal conductivity through the thickness of the film and measure the rest of the properties in-plane. That’s just how it’s done because it’s easier. The next step was to characterize all the properties multiple times. For a lot of the thermoelectric properties, I made many, many samples and tested them a lot of times to get a lot of data so that I was confident about the variability within data. A lot of the collecting and analyzing of data I did by myself. I am the lead graduate student on this, and for measuring the thermal conductivity, we collaborated with the department of mechanical engineering, Dr Jun Liu. Dr Liu is on my PhD committee as well, so he helped me out with a lot with understanding the conceptual aspects of this. Most of the data collecting and the writing of the paper was done by me, and his students helped with the thermal conductivity measures. That’s how it went.

I think some scientific research is, you start with a team of researchers and you all divide tasks. For me, a lot of it was me doing it myself, and then, you know, getting in touch with collaborators such as Dr. Liu towards the end to figure out how to measure the rest of the properties.

 

You enjoyed writing the manuscript?

Oh yeah! I think I love scientific writing in general. By now, in the fifth year of graduate school, I feel more comfortable. I think there is a certain way you have to write, to be impartial about your own exciting results. You have to say that other people haven’t done this, without putting anybody down. You have to be respectful of the science that [already] existed, but also try to say, “we are making a contribution as well”.

 

Cool. What was the major finding of your paper?

I would say the major finding was that we characterized the carbon nanotube materials all in the same direction which isn’t done very often. After this characterization, we realized that they have pretty good thermoelectric properties. Even though these materials are not very expensive, they can be made at a larger scale. These were easy to make, they are flexible, they are strong, they can be integrated into fabrics, and they have decent thermoelectric properties. So, that’s big. If somebody is wondering whether they should use carbon nanotubes, this paper will be helpful for making that decision.

 

Changing gears slightly… what are some of your ultimate scientific career goals?

I think a big thing for me is definitely to communicate science to a lot of people. As many people as I can. Within the scientific community, sometimes there are blind spots. My background is textile engineering and chemical engineering. A lot of researchers are also making electronic textiles, but they don’t think about the textiles aspect of it. So, they would just stick some material on the fabric. Or they would call a ‘fiber’ a ‘yarn’, or a ‘woven fabric’ a ‘knitted fabric’. These things may not seem that important to a material scientist or a mechanical engineer, but from a textile scientist perspective, I feel like if you are going to do innovation in textiles you have to make sure you think about wearability and comfort. No-one is going to wear the fabrics that I make for personal heating and cooling if they’re extremely uncomfortable or itchy. I know if I wear a sweater that makes me itchy, I will throw that sweater away! Even within the scientific community, science communication is required for bridging the gap between what textiles are and how we can make them smarter and electronic. That has been a goal of mine and I have written a lot of articles to kind of bridge that gap.

 

That’s really interesting. So, from the scientific communication perspective, you’re hoping to see more inter-disciplinary communication so that the science can improve in general.

Yeah!

 

So, what does a day in the life of a textile scientist look like?

Well, before the pandemic, we were doing material science but combining it with fabrics. So, it’s one thing to make an electrically conductive film, for example. It’s another thing to make an electrically conducting fiber or thread, you know? A lot of our efforts on a day-to-day basis are making electronic capabilities in a textile or fabric format, and then characterizing those. We do a lot of mechanical characterization and electrical characterization. The rest of it is working like electrical engineers, probing its electrical properties and trying to understand why it works this way or that way. It’s very inter-disciplinary.

 

Do you work within a fabrication facility, what does the lab space look like?

Oh no, it’s not within a fabrication facility. We have a wet area where we do wet chemistry coatings and things like that, but we don’t make any of the molecules ourselves. We obtain them commercially. Everybody always asks [us] “can this be commercialized?”. We always think of everything in terms of high volume in fabrics. So, we obtain a lot of chemicals commercially, but we do a lot of chemical modifications like coating, spin coating, dip coating, things like that ourselves. More complex fabrication techniques, for example chemical vapour deposition or atomic layer deposition… we have a nanofabrication facility on campus that can be shared by the entire engineering community!

 

Did you always know that you wanted to be a scientist, or is it something that you worked out over time?

I think when I was younger, I wanted to be a veterinarian. But then, I didn’t really like biology at all (laughs). I think I wanted to be an engineer after that, because my father was one and I just always found it interesting. I didn’t think I would go into materials and textiles, I always thought I would become a mechanical or electrical engineer, but it just so happened that after 12^th grade, I kind of stumbled onto the field a bit with my undergraduate university and I really liked it. I really liked chemistry and math, but I could never find the thing that bridges chemistry and math. They seem kind of disparate, but they do come together. Everything related to chemical engineering and textile engineering bridges that gap. I would say I always wanted to go into some sort of educational research field.

 

Could you tell us a bit about your research journey, and how you got interested in what you are working on now?

I came to the US in 2015 for grad school. At that point, I knew I was going to do a masters in textile engineering. I wasn’t sure about a PhD and I didn’t even have an advisor. I spoke with my [now] advisor Dr. Tushar Ghosh in the third week of grad school. He gave me a couple of papers to read on the research he had done. I found them quite interesting… but I also didn’t understand what they were talking about. So, I highlighted a bunch of stuff, and I had about twenty different questions. I went to him the next day and said, “I like these papers, but I have so many questions. I want to understand what is going on!”. I think he liked that about me, he thought it was good that I had showed some interest in reading the papers. When he asked me, “What did you get from it?”, I wasn’t just like, “Oh yeah, I understood, it was fine”. I actually had the inquisitiveness to ask questions. I just so happened to talk to him about being his grad student, and he had this amazing electronic textiles research that he has been doing for 25 years. It was just serendipity, I think.

 

I’m sure your advisor does love when people come back with questions, and I’m sure you’re the same now too. For instance, when you have undergraduate students who come and say “I have all of these questions about your paper!”, it’s absolutely a YES! moment, YES! that I get to talk about all of this with someone (laughs).

Sometimes I can see when I am explaining something to an [undergraduate] intern, I can see from their face that they don’t get anything I’m saying. Then when I ask them if they got it, and they say yes… I know that they didn’t get it (laughs). So, I don’t want to force anyone to ask questions when they don’t feel comfortable, but I do sometimes feel like saying to them, “I didn’t get any of this either and you can just ask me!”. I was really happy to ask questions.

 

Definitely. I think people especially within the sciences are afraid to admit “I have no idea what any of this means”. We are scientists, so we sometimes hold up this front as if we understand everything, when really, it’s a lot smarter to understand how little we actually know! In lab meetings, I’m always putting my hand up and saying “I have a really stupid question”, but generally other people are glad that I asked it, because they were wondering about the same thing.

I have stopped even saying that I have a stupid question. It used to affect my self-confidence. I just stopped even saying it. It’s not stupid, it’s just a question! I’m not stupid, so I’m not asking questions that are stupid. I’ve stopped giving them a preamble, I just say “I don’t understand what this means”.

 

That is so true, a good bit of advice!

Do you have a science fact that you would like to share with us? It doesn’t have to be related to materials or engineering.

Sometimes I don’t understand anything about biology. I always read Wikipedia pages about biological things to understand myself better, I guess. I am fascinated by oxytocin. What an insane molecule. The way it affects how we feel about people who look like us, and who resemble our appearance and skin colour. It makes us trust those who look like us more. I think that we don’t realize what constitutes us at a hormonal level. Me too, I’m examining my biases and trying to be a better human being. I get frustrated when I’m not able to move forward through a backwards thought process. I try to be kinder to myself by understanding these kinds of systems. It’s so crazy the role [oxytocin] plays in everything that we feel and perceive.

See the Wikipedia page for the neuroactive chemical oxytocin that Kony is referring to here, which references one study on oxytocin and human ethnocentrism.

 

What would be your advice for a young person looking to get into material science research?

The biggest advice would be that you should know the periodic table really well. I don’t just mean what element comes after what, not just the [mnemonic] song, but what happens when you go up and down, left to right. What is the periodicity of elements? How does that affect their behavior? There are the inorganic materials, and then there is organic which is basically dominated by carbon. Either of those. I think having a good background knowledge of chemistry is valuable. More than physics. If you know your chemistry, then you can do material science really well.

 

Cool. This reminds me that I definitely need to brush up on my chemistry (laughs).

I do it all the time. I find myself reading about molecular orbital theory every other week. That helps me understand how semiconductors work. Those things are so basic and we learned them a long time ago, so it’s easy to forget but they become important later. Not overtly, I mean, no-one is going to stop me in the hallway and say, “well… what is sp2 hybridization?”!

 

What qualities would you say make an excellent scientific mentor?

I think my advisor is a really good mentor for me. I think his qualities that I have appreciated and that I think make a good mentor are, overall, he is very patient. That is important in a mentor. That they are patient, and they trust that the graduate student also has their own ideas and understanding of the experiment. Of course, the mentor knows a lot more about the field and the overall vision, but on a day-to-day level, since the students are doing the experiments, it’s important to consider their recommendations as well. I think it is hard, you want the person you are mentoring to have independence, but you also don’t want them to keep making the same mistakes. I think having patience and trust, you know, that can help create good graduate students.

 

Definitely. You make a good point about trusting the people that are actually on the bench every day. They are going to see things and come up against problems that their mentor might not have considered or isn’t intimately familiar with. I remember my graduate advisor was very much like that, he would say things like “Oh you know much more about this than me!”. He questioned me, but ultimately, he trusted me which was amazing - and I agree that it’s a trait of a good mentor.

You have served as President of the GWIS Research Triangle. Tell us a little bit about your role there and what you were able to do in that time.

I started in year one as the membership secretary, and then was President for two years of the Research Triangle chapter. The one big thing that we started while I was President was the endowment fund that now gives out a $500 travel award to women scientists who want to go to conferences, etc. Last year we had our first winner, this year we have another one. They are both amazing scientists and really interesting women. This year, we actually let them use that money for anything related to their academic expenses - it didn’t have to be travel. So, that was big. I think we needed some direction in terms of what we were going to do with some of the excess funds we had. [We had to think about] “how do we start an endowment account? How do we convert that into travel awards?”. So that was a big one. In general, we put up a lot of events. An event every month on average. We worked with all the way from elementary school girls to leading career scientists. So that was really cool for me, to interact with people from so many different age groups and backgrounds. I think the other people within the chapter profited from that too.

 

Yeah that’s awesome. I’m looking forward to a time where we can all meet and have events like that again!

I almost feel like it will never happen, but I think I am just a bit pessimistic (laughs).

 

It’s been a crazy year, for sure!

Finally, and this is an important one for GWIS, what headway would you like to see made in terms of supporting women to reach their full potential, and be recognized for that, within their scientific careers?

I’ve been thinking about this too. My experience has been unique, I am also an immigrant, so I think the thing is, of course, financial support is very important for women to become scientists, but I think the most important support is familial. My family has been extremely supportive of me working long hours. My parents supported me to move from India to the US by myself. If these support systems didn’t exist for me, I wouldn’t be able to be a scientist. Recognition is one thing – yes it feels good to be recognized – but if I don’t have the familial support and always have the background stress like “my parents don’t trust me to go outside and be a woman of my own”, then I would never be able to concentrate on research. I think the most important thing is having that familial support. Having a support system that trusts you, that you are making the right choices to go into a male-dominated field, or to become a scientist… or not come home at 8PM but come home at like 1AM from the lab. So that’s something that is so important. The women that don’t have that support system, if they have a toxic support system, I would say that you have to be brave enough to not be in that environment. I feel sometimes myself too that I am emotionally conditioned to always see the good in other people, and to be a caretaker, and not see the toxicity of people trying to hold me back -  but we need to stay focused on moving ourselves forward from those situations. 

 

Wow. It’s something that is so pertinent for women scientists and it’s not something that I had thought about or articulated so directly in this way.

I have a lot of friends who say to me “my parents would never let me go to a western country by myself”, or, they say “they would never let me get married to someone that I choose”. It’s a reality, unfortunately, to some extent in my culture. I think about it a lot more. Maybe other immigrants from countries like mine would think about it more. I think that’s important.

 

Thanks so much for chatting to me, Kony. Is there anything you would like to add or anyone you would like to acknowledge?

Ah, actually, I would just really like to thank you for talking to me. It’s really nice to talk about myself – I don’t normally do that. I was so happy to read your blog and read about other scientists! So, I just want to acknowledge you and your work. I know it takes your time but I’m really glad you are doing it!