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Intro (00:04):
Trailblazers in research, innovators in technology, and those who simply have a good story: all make up the fabric that is ����AV. We're taking on the grand challenges that face our students, graduates, and higher education is our mission and our passion. Hosted by Mason President Gregory Washington, this is the Access to Excellence podcast.

President Gregory Washington (00:27):
Every day at ����AV, our faculty are developing innovative solutions to the world's grand challenges. And the great thing about innovation is that sometimes those grand challenges can have small solutions that come from the most unlikely of places. Joining me today is someone who knows quite a bit about finding big solutions in small, unlikely places: like the bottom of his coffee cup. Jeffrey Moran is an assistant professor in the Department of Mechanical Engineering and is an affiliate faculty member in bioengineering. His research lies in understanding and using microscale thermofluid transport phenomena to enable new solutions to fundamental challenges facing humanity. Jeff, welcome to the show.

Jeffrey Moran (01:22):
Thank you so much for having me. It's a pleasure and an honor to be here.

President Gregory Washington (01:27):
What some of you may not know is that Professor Moran and I have a connection, a really, really strong one. Uh, your postdoc advisor?

Jeffrey Moran (01:39):
That's correct.

President Gregory Washington (01:40):
His postdoc advisor at MIT was a former student of mine back at Ohio State, and so we have a very, very close connection in terms of the work that he's actually doing.

Jeffrey Moran (01:55):
I think we actually met before I came to Mason at one of the cookouts that he had.

President Gregory Washington (02:01):
Oh, that, that could very well, could very well.

Jeffrey Moran (02:03):
I think you were visiting Boston and he had occasional get-togethers, Professor Cullen Buie is his name. And he actually just made full professor at MIT, you may have seen.

President Gregory Washington (02:13):
Yeah, I did. Yeah, I did. And I, I actually have not congratulated him. Yeah. So I need to go back and make sure he knows how proud of him I am. So let's talk a little bit about your work.

Jeffrey Moran (02:24):
Sure.

President Gregory Washington (02:25):
So your work is in the field of microscale transport phenomena.

Jeffrey Moran (02:29):
Yeah.

President Gregory Washington (02:29):
And for those listeners who are out in the audience, who could be just in other fields or students, can you explain a little bit of what that actually is?

Jeffrey Moran (02:40):
Sure. So transport phenomena is a, a somewhat wonky term that basically means the science of how stuff goes from one place to another. And that sounds broad because it is, the stuff could be literal stuff like matter. Think about a drop of food coloring spreading in a glass of water. And if you don't stir the water, then the food coloring spreads smoothly and radially outward in a process called diffusion. It could be something like that, but the stuff could also be something like heat or something like electrical charge, or even fluid motion, a little vortex or an eddy. So transport phenomena, you could argue, underlie just about everything that happens in the universe. But usually when people use that term, they're referring to artificial, engineered systems. And I'm really fascinated by this topic because there are a lot of parallels in the way that different types of things are transported from place to place.

Jeffrey Moran (03:46):
I mentioned the example of food coloring spreading in a glass of water. There's also heat, right?

So you could imagine, like, your stove top in the morning after you make coffee in the morning, you turn the heat on and the temperature is hot right in the center of the burner. And then it spreads radially outward after you turn the heat off. And it turns out the math that describes that process is essentially identical to the math describing the food coloring: diffusing. And so it's fascinating from a fundamental perspective, but it's got lots of applications, especially in things like the chemical industry or in, uh, microfluidics: the science of fluid flow through small passageway. And the microscale is just referring to the fact that I like studying these phenomena at the microscopic level. And my fascination really derives from the fact that we can see some really bizarre consequences of those transport phenomena that you would never see at the macroscopic scale. And we'll get into this, but these include things like a tiny piece of platinum connected to a tiny piece of gold actually propelling itself at the microscale in hydrogen peroxide. Something you would never see at the macroscopic level. So that's a bit of a flavor of what transport phenomena refers to.

President Gregory Washington (05:06):
Well, that's interesting. So what do these phenomena look like?��

Jeffrey Moran (05:10):
Yeah. So some of them are visible to the naked eye, like I was saying, with the dye spreading in water. Some of them are invisible or they're only visible under a microscope. Something like molecules moving from place to place. Some of them are completely invisible. Like for example, my PhD work was studying these self-propelled particles, right? We're, and we'll talk a lot about these, but these are tiny rods, small enough that you need a microscope to be able to see them. And what's fascinating about them is that they actually propel themselves by pushing an electrical current through the solution. So ions are generated on the front end and consumed on the back end. And as a consequence of that, ion motion propulsion is generated. So that's invisible, right? Because if you were to just look at it under a microscope, you would just see the rods zipping around in the fluid in the presence of hydrogen peroxide. So some of them are visible like the dye spreading in the glass of water. Some of them are invisible, like the charges moving their way through the solution and ultimately causing a variety of different forces to be generated that lead to propulsion. So it really depends on the type of transport you're talking about.

President Gregory Washington (06:30):
So as a young person who's gotten into this field and developing a passion for it, how did that develop? What connected you to start looking at the micro and nano scale?

Jeffrey Moran (06:44):
Yeah. So I got into research late in my undergraduate days. I was participating in a program where undergraduates could be paid to do research in a professor's lab. We have an analogous program at Mason called the Undergraduate Research Scholars Program, through which I've mentored about nine undergraduate students. And part of the reason for that is that I, it was such a valuable experience for me, and I just had the chance to work for a professor whose lab focused on microfluidics. As far as how I got into the self-propelled particles specifically, that was by accident. It happened when I went to a master's thesis defense early in my graduate school days. And there was a student who was defending his master's thesis. And the thesis topic was how to manufacture the platinum gold rods I was talking about. And the focus of his work was on more efficient ways to manufacture them.

Jeffrey Moran (07:44):
But he just happened to mention offhand that they happened to propel themselves in water, if you add hydrogen peroxide as a fuel, and that intrigued me. So I raised my hand and I said, how did they do that exactly? And it wasn't really his main focus, but he, his explanation, so he can be forgiven for giving a somewhat arm wavy explanation, but he basically said, well, we don't really know, but it's, it has something to do with the flow being induced in the fluid near the rod's surface. And you know, the flow goes backward and the rod goes forward. And I sat back and I thought, Hmm. So I had the fortune of having a three year fellowship that allowed me the freedom to pursue whatever I wanted for my thesis work. So I approached my advisor and told him I was interested in really getting to the bottom of this.

Jeffrey Moran (08:41):
And that eventually became my thesis. And you know, this is a very young field. It just started in 2004, and so it's just passing the 20 year mark. And I've just never been able to shake off this fascination with how we can make these seemingly inanimate objects that are not living in any way move and do things that mimic biological systems at the microscale. And as an engineer, I'm especially interested in what practical applications these sorts of devices could have. So my fascination with this really arose from that chance encounter at that thesis defense. But people have been thinking about this for a while. You know, there are classic films like Fantastic Voyage from the 1960s where a team of scientists shrink their submarine down small enough to enter the bloodstream of a colleague and treat a blood clot in his brain. So people have been thinking about this and what applications it could have, ways it could revolutionize medicine for, for quite a while.

Jeffrey Moran (09:45):
And at Mason, I'm really trying to marry that fascination that I still have from my graduate school days with a sort of utilitarian outlook and thinking about ways that we can start to realize the vision articulated in things like the Fantastic Voyage film. So that's a little bit about how my fascination came about. You know, when I worked for Professor Buie at MIT, we were doing different things. We were working on some different areas. And it was still in the general field of transport phenomena, but it was much more focused on like batteries and energy devices. So this is a really multidisciplinary field. Transport phenomena cover a lot of different application areas.

President Gregory Washington (10:25):
Well, let's talk about that. Because that is what is so incredibly fascinating. Mm-Hmm. So earlier this year, members of your lab made the news with the invention of what's being called the CoffeeBot. And this is spent coffee grounds coated in iron oxide that can absorb pollutants and water.

Jeffrey Moran (10:49):
That's right.

President Gregory Washington (10:49):
So tell me about how it works.

Jeffrey Moran (10:51):
Sure.

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President Gregory Washington (10:52):
How do they move through the water? And then let's, let's get into it a little bit.

Jeffrey Moran (10:56):
Yeah. So on that topic, I actually brought some visual aids here. So the, the listeners can't see this, but I'm holding a vial of what are just ordinary coffee grounds, right? And these are coffee grounds I literally brought from home.

President Gregory Washington (11:13):
Now spent coffee grounds, which means...

Jeffrey Moran (11:15):
Spent coffee grounds.

President Gregory Washington (11:15):
Which means they've been used.

Jeffrey Moran (11:16):
That's correct.

President Gregory Washington (11:17):
That's even better.

Jeffrey Moran (11:18):
That's correct. Yeah. And by one estimate, we throw away about 23 million tons of spent coffee waste per year. Much of that is being sent to landfills. Although increasingly I'm heartened to see that places like Starbucks are making just bags of the stuff available for folks to use for compost. So I've got a vial of spent coffee grounds here, and in my other hand I have a magnet. Now, if I hold the magnet up to the vial, nothing interesting happens. Coffee is not magnetic. However, if I have another vial here, these also look like spent coffee grounds. They are. But they've been coated in, as you said, iron oxide, which is the main chemical constituent of rust. So we sometimes call these rusty coffee grounds because in a real sense, they are rusty. And if I hold the magnet up, I don't know if you can see, uh, and for the listeners, the coffee grounds, once they've been coated in the iron oxide particles, they will actually follow the magnet.

Jeffrey Moran (12:19):
So I can make them go wherever I want to by holding up a magnet to it. So the essence of what we did was develop a safe and eco-friendly approach to coating the coffee grounds with these little tiny bits of rust. So what does that do for us? Well, it does two important things. First, it allows us to use magnetic fields. You asked how they move. It allows us to use a magnetic field to drive them through the water. So for now, we're just propelling them with the external magnetic field. We can come back to that in a second. We're looking at ways to improve upon that. And one of the things we demonstrated was that moving coffee grounds will actually remove pollutants from water more efficiently than stationary ones do. And this makes intuitive sense because, in a sense, the moving coffee grounds encounter more pollutants per unit time than stationary ones do. So we demonstrated three different pollutant types: methylene blue, which is kind of a stand-in for a chemical pollutant. But methylene blue itself is a textile dye that has some negative health effects, that is itself a pollutant of concern in some areas of the world, particularly where textile production is common. Oil spills and microplastics: those are additional pollutants of concern.

President Gregory Washington (13:41):
So both of those are problematic...

Jeffrey Moran (13:43):
Absolutely.

President Gregory Washington (13:43):
Today.

President Gregory Washington (13:44):
Oil spills and microplastics. So much so fish today have an incredibly large amount of digested microplastics in their systems.

Jeffrey Moran (13:56):
And potentially we do too, potentially. And because there are so many consumer products that contain plastic, they make their ways into waterways, right? And eventually in some areas, uh, it probably varies significantly. I haven't seen the statistics, but definitely lots of different forms of life are consuming these microplastics. And I wanna say, this is not my area, but I think we're still, as a community, figuring out exactly what the health effects are. But they're definitely something to be concerned about for sure. So we demonstrated that we can remove each of those three types.

President Gregory Washington (14:30):
So microplastics...

Jeffrey Moran (14:32):
Mm-Hmm. Oil and methylene blue as a model for a dye—methylene blue is, is a textile dye. And it's blue, as the name suggests. And that was convenient because then it's very straightforward to monitor how much of the methylene blue we've removed at any given time. Because you can use an instrument that essentially looks at how much blue light is being absorbed. You can use essentially the intensity at a certain wavelength to determine how much of the dye is left. So it was, it was partially out of convenience that we chose that.

President Gregory Washington (15:06):
Hmm. So reuse of these coffee grounds was mentioned.

Jeffrey Moran (15:13):
Yeah. Yeah.

President Gregory Washington (15:14):
So how often can you use them?

Jeffrey Moran (15:15):
Yeah. So that brings me to the second major thing that the magnetism enables. So just to recap, the first thing the magnetism does is it allows us to drive them through the water. And that speeds up the pollutant removal process. The second thing it does is it allows us to take the magnet and pluck the coffee grounds out of the water after the treatment is complete. What we do next is rinse it off. We can rinse the pollutants off, and we do still have to dispose of the pollutants elsewhere. That is a separate issue that is, for now, tangential to the work that we're doing. We're mainly focusing on removing them from the water. But that is something that you do still have to do something with—the oil or with the microplastics. And that's something that other researchers are working on.

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Jeffrey Moran (16:00):
So then after you rinse them, we typically rinse them with an organic solvent like acetone. Acetone works pretty well. And then you can actually drop them back into the water. And we showed in the journal paper we published on this that you can reuse them at least four times with a minimal reduction in pollutant removal efficiency. So we haven't gone beyond that. But based on how well the first five trials went, and this is true, by the way, with each pollutant class: with dyes, oils, and microplastics, we have reason to believe that you could go further.

President Gregory Washington (16:34):��So let me get this straight 'cause I want to make sure that the folk out there see the depth and the profoundness of what you are stating. Spent coffee grounds coated and iron oxide can be dropped into, say, an oil spill.

Jeffrey Moran (16:56):

Absolutely.

President Gregory Washington (16:56):

And the coffee grounds will attach themselves to the oil.

Jeffrey Moran (17:00):

That's right.

President Gregory Washington (17:01):

You have a process for then pulling those grounds, separating those grounds with the oil on them from the water. The oil is rinsed off where it can be disposed. You throw the grounds back out to repeat the process. And you can do it up to four times.

Jeffrey Moran (17:18):

Five times total. Right. So four reuses.

President Gregory Washington (17:21):

Four reuses.

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Jeffrey Moran (17:22):

So five times total. So five total uses.

President Gregory Washington��(17:23):

That's amazing.

Jeffrey Moran (17:24):��You nailed it. That's exactly right.

President Gregory Washington (17:26): And so when you talk about the coffee grounds attaching themselves to a pollutant like oil, or microplastic, how long does that take? Is it an immediate attachment or...

Jeffrey Moran (17:36):

So that's a good question. And it's one that we are really working on answering more systematically, to really be able to say, if you have, say, a section of a river that has a certain area, say, an acre, and you have a rough estimate of how much oil has spilled, there's been an oil spill and some X number of liters. We don't really currently have a number to say definitively, this is how much coffee you would need for that section of the river. But much of the testing we've done so far has been mainly on the size scale of, you know, a small beaker, a small container. That's maybe, maybe a quarter of a liter of water. And we can get away with about 50 milligrams of coffee. So just enough to sprinkle the coffee bots in a, a layer that will approximately sparsely coat that top layer.

Jeffrey Moran (18:33):

And then as you say, the pollutants attach themselves to the coffee grounds.

President Gregory Washington��(18:37): Does that happen immediately?

Jeffrey Moran (18:39):

It's not immediate. So it depends actually on how, whether the coffee grounds are moving, first of all. So if they're stationary by themselves, the testing we did was on the timescale of about 40 minutes. And after 40 minutes with stationary coffee grounds, some of the pollutant has been removed. Right? But if you drive them through the water, it increases from about 50, 60% to about 90 to 95% in the case of methylene blue. In the case of oil spills and microplastics, it's on a similar order.

President Gregory Washington (19:12):

Wow. That's amazing. So...go ahead.

Jeffrey Moran (19:15):

Oh, I was just gonna say, because another question that I've gotten a lot, and that is a good question, is what is it that attaches the pollutants to the coffee grounds?

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Jeffrey Moran (19:24):

Right. That's a fair question. And in the case of oil spills, it has to do with a property called hydrophobicity. And it means basically, as the name suggests, hydrophobic, it turns out that the coffee grounds are what we call hydrophobic. So for folks listening out there, if you've ever waxed your car, right? And you put some droplets of water on afterward, it kind of beads up. Because the wax has rendered the surface hydrophobic. It doesn't like water. So when water comes in contact with it, it tries to avoid touching the surface as much as possible. So that's why it forms that bead. And we have some pictures from the paper where if you take a bed of spent coffee grounds, it does the same thing. So why does that matter? It matters because things that don't like water tend to like oil. So the same interactions that cause oil droplets to coalesce together in say, salad dressing are also the forces we believe, and we have good reason to believe, that cause oil to glom onto the coffee bots. And there's some nice videos that are included with the paper, and also in the news segment that was featured on Channel 9 news in March of this process actually happening. So it looks kind of like the coffee grounds are kind of soaking up the oil.

President Gregory Washington (20:50):

Huh. Amazing.

Jeffrey Moran (20:51):

Yeah. And a similar thing we think is happening with microplastics, because microplastics are also hydrophobic in general. So it's a good rule of thumb that hydrophobic things tend to like to congregate with other hydrophobic things.

President Gregory Washington (21:05):

Okay. So you know, this is amazing. So the question that I always have when confronted with, you know, this is an everyday product.

Jeffrey Moran (21:17):

Sure.

President Gregory Washington (21:18):

You know, we toss the coffee grounds all the time.

Jeffrey Moran (21:22):

That's right.

President Gregory Washington (21:23):

How did you discover such a use out of something that most of us consider trash?

Jeffrey Moran (21:28):

Yeah. This is where I have to give credit to my group members. So I had two awesome members of my group who have since gone on to other things. It was a postdoc in my group named Amit Kumar Singh. And at the time, a high school senior named Tarini Basireddy. Amit is now a professor himself at a university back in India. And Tarini is just beginning her sophomore year at Johns Hopkins. We were trying to figure out a project for Tarini to work on, because she was doing a year long internship in my lab as part of a, she was a senior at Thomas Jefferson High School. And they had this program where, um, their seniors can do research internships, and Mason, quite understandably, has restrictions on things that minors can do in the lab.

Jeffrey Moran (22:18):

Uh, so what happened was, you know, we were thinking about a project that would involve the things that I was interested in on using particles that move in liquids that would not involve any particular hazards. And it was one of those, Hey, what if we tried this kind of conversations that I've come to love, I've come to treasure those conversations because they can lead to interesting things like this. And I should say, we are not the first people to use self-propelled or magnetically propelled nanoparticles or microparticles to clean up water. There have been a variety of different studies in that direction already. The problem is a lot of those are just proof of concept demonstrations, that if you have a particle that's made of maybe a metal or some other toxic substance, but if it moves and it's able to break down pollutants, you know, people will publish that and they'll say, look, we can use propelled particles to clean up water. But one of the major focus areas of my lab in general is trying to engineer these kinds of particles from safe materials. And we were brainstorming one day and one of us said, I'm not sure that it was me. I don't think it was me. One of us said, what about coffee as a way to demonstrate water treatment with active particles?

President Gregory Washington (23:40):

Yeah. But why would they say coffee? You know what I'm saying? It makes, absolutely, that's not what you would think of when...

Jeffrey Moran (23:47):

Yeah. Well I have, uh...

President Gregory Washington (23:50):

I mean, I would think of sand before I would think of coffee.

Jeffrey Moran (23:52):

Yeah, absolutely.

President Gregory Washington (23:53):

You know what I'm saying?

Jeffrey Moran (23:54):

Well, sand is another material that we work with or silicon dioxide. And we'll, we will get to that in a separate project. But, you know, my postdoc, particularly Amit, I used to say, you give him any three materials, he would figure out a way to make, make a self-propelled particle out of it. And so he had a previous paper on using tea buds, like bits of tea, to make nanoparticle antibiofilm treatments. So things to treat bacterial biofilms, for example, which are part of how antibiotic resistance comes about.

Jeffrey Moran (24:28):

So it was just one of those random sort of suggestions that once somebody said it, we all kind of sat back for a minute and thought about it. And it started to make more sense. Because first of all, as we've already said, coffee is discarded by the millions of tons every year. It is hydrophobic. So it, it can pick up other hydrophobic things. And if you look at a microscope image of a coffee ground, it has this very irregular, very dense surface where what I mean is that there's a lot of active surface area given the size of the coffee ground, which means it can pick up a large quantity of pollutants relative to its size. So the answer to the question "why coffee?" is really three-pronged: it's hydrophobicity, it's common and it's relatively safe to work with, and it has a high surface area to volume ratio, which turns out to be important.

President Gregory Washington (25:25):

Hmm. That is amazing. So what do you think a discovery like this could have on protecting and preserving water systems around

Jeffrey Moran (25:35):

Yeah, I mean, we certainly hope that this has far-reaching impacts across the world. In many regions, two things are true at the same time: one, there is an urgent lack of clean, accessible water, and two, coffee is produced and consumed in large quantities. Take Ethiopia, for example. It's currently facing a water crisis, and they also grow and consume more coffee than any other African country, to my knowledge. Brazil, Vietnam, Peru, and other coffee-producing countries face similar challenges. The issue often isn't a lack of water, but rather a lack of access to methods to decontaminate it without needing complex infrastructure, which isn't always available.

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Jeffrey Moran (26:42):

So our goal is to eventually disseminate this method, allowing people with little scientific training and without access to advanced equipment—like the nano-fabrication tools many in my field still use—to make use of materials they already have. For instance, it could be implemented in the home to decontaminate a simple cup of water. You could even imagine it being deployed in small boats, where a magnet on the boat could drag a bed of "coffee bots" to clean up an oil spill in a river. News segments have animated this process. In sewage treatment plants, where sewage is left to sit and decompose, you might just need to place coffee grounds on top. We believe this will absorb pollutants more efficiently than just leaving the sewage to decompose naturally.

President Gregory Washington (28:12):

Huh. Interesting.

Jeffrey Moran (28:13):

Yeah, there are a lot of potential uses. We’ve applied for a patent on this.

President Gregory Washington (28:21):

Yeah, you should.

Jeffrey Moran (28:22):

We published this work in a scientific journal a few months ago. Tarini, now a sophomore in college, is a joint first author on the paper.

President Gregory Washington (28:31):

Wow.

Jeffrey Moran (28:31):

And I have to say, at her age, I didn’t even know what research was.

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President Gregory Washington (28:35):

Let’s be clear—most high school seniors don’t get a publication.

Jeffrey Moran (28:42):

Oh yeah.

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President Gregory Washington (28:43):

A first-author publication, no less. That’s really cool. Your previous advisor at MIT, when he was my student, came to me after his freshman year to start working in my lab.

Jeffrey Moran (28:57):

I remember that.

President Gregory Washington��(28:58):

So you're keeping that tradition alive.

Jeffrey Moran (29:02):

<laughs> Yeah.

President Gregory Washington (29:02):

That’s phenomenal.

Jeffrey Moran (29:03):

Getting started early.

President Gregory Washington (29:05):

Exactly. You see where it can lead. I hope you stay in contact with her and guide her toward grad school.

Jeffrey Moran (29:16):

She definitely has a bright future ahead.

President Gregory Washington (29:18):

Outstanding. Now, shifting gears a little. In August, it was announced that you and a colleague from Purdue University received NSF funding for a study to be conducted on the International Space Station. The goal is to better understand thermophoresis, or the migration of particles in response to temperature gradients, which can happen with or without gravity. Since your work typically focuses on particles moving through water, how did you realize there was a gap in knowledge about how aerosols migrate in response to temperature without gravity?

Jeffrey Moran (30:02):

Mm-hmm <affirmative>. Yeah, so this is another example of a project that came from a casual “what if we tried this” conversation. The impetus was the National Science Foundation’s program called��Transport Phenomena Research on the ISS to Benefit Life on Earth. Transport phenomena came up again. I should also mention that I’ve been obsessed with space since I was a kid. My childhood home is still filled with drawings of space shuttles and models of fighter jets. That passion for space was one of the reasons I got into engineering.

President Gregory Washington (30:45):��I can relate to that.

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Jeffrey Moran (30:48):

I’ve wanted to be an astronaut for a long time. I applied in 2016 but wasn’t selected. Still, sending an experiment to space is the next best thing.

President Gregory Washington (31:09):

Exactly.

Jeffrey Moran (31:10):

So I was talking to my friend and collaborator David Warsinger—we’re going through the junior faculty process together. We met at MIT when he was a grad student, and I was a postdoc. I mentioned this project, and he asked, “Has anyone made a micro-swimmer that moves in air?” A micro-swimmer refers to self-propelled particles, also known as micro-motors or active colloids. Initially, it seemed like an odd question since my field is mostly concerned with propulsion through liquids and gels, not air.

President Gregory Washington (31:52):

But air is a fluid in some sense.

Jeffrey Moran (31:55):

Absolutely, yes. That got me thinking. It was a bit like the time in 2008 during my master’s defense when someone mentioned that particles could swim. I sat back and thought, "Huh, how might that work?" I began considering mechanisms active in both liquids and gases. One of those mechanisms is thermophoresis, a transport phenomenon where particles in a temperature gradient—where one side is cold, and the other is hot—experience a force that pushes them either toward the hot or cold side.

President Gregory Washington (32:59):

Oh. So the force works both ways?

Jeffrey Moran (33:02):

It depends.

President Gregory Washington: (33:02):

So it's not always hot. Usually, it's cold to hot, right?

Jeffrey Moran (33:05):

In liquids, it can be in either direction.

President Gregory Washington (33:08):

I see.

Jeffrey Moran (33:08):

It depends on the liquid and it depends on what you add to the liquid. And I should mention in liquids, it's not really fully understood exactly what causes it to move towards hot or towards cold. In gases, however, it's more straightforward. In gases, motion by thermophoresis pretty much always occurs from hot to cold. So if you have a particle that's in air, and the air is hot on one side and cold on the other, then the nitrogen and oxygen molecules on the hot side are by definition zipping around with more velocity, right? When they collide with the surface of the particle, they impart a force to it. On the cold side, they're zipping around with less energy. So the force that they impart from the cold face is less. And so the end result is that there's a net force owing to the more forceful collisions on the hot side that pushes the particle towards cold.

Jeffrey Moran (34:02):

So this is known to happen in gases, but then I got to thinking, okay, could we then quantify it somehow? And it's difficult to do on earth because of things like gravity, which will cause the particles to fall out of the air. And there's an additional problem with thermophoresis because hot air rises, right? So if you were to try to have a sample of particles and air, and you somehow kept them from falling to the ground and you heated the air on one side, it would rise. And that would cause the particles to move. And it would be hard to discern how much of the particle motion is really due to thermophoresis in that case.

President Gregory Washington (34:41):

I see. I see.

Jeffrey Moran (34:42):

So what we realized was that in microgravity on the international Space Station, you don't have those confounding factors, right? And it would be possible, we think, to isolate just the component of thermophoresis that drives different types of particles through air.

Jeffrey Moran (35:03):

So why would anybody care about this? Right. That was kind of the next question that we had while we were thinking about this. And it turns out that aerosols, small particles suspended in air, are very important to our understanding of the global climate. And they pose a pretty large amount of uncertainty actually, in terms of what their net effect is on the global climate. Some aerosols actually can exert an overall cooling effect. Some aerosols warm the planet. Aerosols are produced by volcanic eruptions, dust storms, other natural events like that. Human activity like burning fossil fuels also injects a bunch of aerosol into the atmosphere. And so it's a very active area of research in climate science right now. And so what we're intending to do is take measurements of how efficiently different aerosols move by thermophoresis. And the hope is to help climate scientists understand how important this mechanism is in the atmosphere, because the problem of aerosols in the atmosphere is only gonna increase. Rocket launches are another major source of, uh, space junk that can sometimes be in the aerosol range. Um, and it turns out that this phenomenon, thermophoresis, is most important at very high altitudes.

President Gregory Washington (36:27):

Hmm. Interesting.

Jeffrey Moran (36:28)

So that's one part of the project. And the, the swimming part, the self propulsion part is to look at whether, instead of say applying heat on one side and cold on the other side, looking at just a single particle with half of its surface coated in a metal, something that absorbs light really efficiently shining a light on it, and then seeing if the metal side absorbs the light more efficiently than thus heating up faster, that will then heat the air surrounding the, the metal side leading to propulsion. This is something that's been demonstrated on earth but has never been seen in air before. So we call this self-thermophoresis because here the particle doesn't require an external temperature gradient, but it generates it itself and then moves. So we're gonna also see whether that happens and we call those micro flyers instead of micro swimmers

President Gregory Washington (37:18):

<laugh>. That is a great way to describe them. Hey, so there's a healthcare, uh, spin on this as well, right? I mean aren't the vectors for carrying disease, especially Covid, for example, as carried like an aerosol.

Jeffrey Moran (37:35):

Yep, absolutely.

New Speaker (37:36):

And so, so you have, if you can deliver something harmful using this mechanism, you can actually deliver something helpful.

Jeffrey Moran (37:47):

That's right. That's right. So I think NASA would probably balk at the idea of us sending virus-laden aerosols to the space station. They might have one or two issues with that.

President Gregory Washington (37:58):

<laughs> I understand.

Jeffrey Moran (37:58):

But it's a very good point. And that is an additional application we're interested in because if we find that thermophoresis indeed is an efficient way to move aerosols around, this could suggest another method to collect virus laden aerosols from say, the HVAC systems of hospitals, right? Which is obviously a big problem there. And we're still figuring out exactly which aerosol materials we're going to send. So we launch sometime likely in the second half of 2025. And most of the materials we're interested in are things like, I mentioned sand earlier, sulfate aerosols. These are aerosols that come from volcanic eruptions. They're also geoengineering proposals to intentionally inject aerosol to cool the planet.

Jeffrey Moran (38:53):

Obviously controversial. Lots of research going on into them. So we're looking at that: sodium chloride, believe it or not, table salt. Comes from sea spray. And that can actually drift to different parts of the globe. And that can affect the climate in ways that we don't fully understand. But we're also looking at something that could act as a stand-in for an aerosol that is produced by say, somebody coughing or somebody sneezing, and we'll see what we see. But you could easily envision, and this has somewhat been explored before, but you could envision, say, having a stream of air where you have the stream going in one direction, and then a temperature gradient perpendicular to the stream of air so that the particles, the aerosols, if they migrate thermophoretically, they would bend toward the cold side. And just be collected on the cold plate. So the viability of that, you know, that is something you could in principle test on the ground, you could test

President Gregory Washington (39:49):

On the ground and you can test that at scale.

Jeffrey Moran (39:51)

Yeah, that's right. So what's gonna happen is on the space station, there's actually a microscope on the space station already. And so what we're doing is designing and building a, an apparatus to apply the temperature difference to a series of different cuvettes--tiny transparent containers--that each of which contains a different particle sample. And so the ISS crew is going to then look at those different samples, apply the hot and the cold as needed. We're gonna be able to watch in real-time as the astronauts perform the experiments and measure the migration speeds of these different aerosol particles as a function of say, what type of particle they are, you know, the temperature difference, things like that.

President Gregory Washington (40:39):

As we start to wrap up here. So what drives you to, towards this sort of innovative research?

Jeffrey Moran (40:46):

I could sum it up in one word, which is curiosity.

President Gregory Washington (40:51):

Hmm. Interesting.

Jeffrey Moran (40:52):

I have in this job as a, one of my favorite parts of this job is that I have the privilege to pursue ideas that pique my interest without much more of an imperative than that. Actually, Professor Buie, my mentor, your protege, he once described it as being an idea entrepreneur. And, you know, it sounds like him, right? He's, he, he's, he's got a way with words, with he is a way of coining those kinds of phrases. But I think it captures a lot of what I love about this job, along with, of course, working with and teaching and mentoring students. That's definitely another favorite portion. But like I said, you know, both coffee bots and this ISS project both grew out of just conversations I was having. That piqued my curiosity. And because I have this role, I was able to follow up on that curiosity.

Jeffrey Moran (41:46):

And in the case of the ISS project, write a grant proposal about it that just so happened to be funded. And so I really think curiosity-driven research is a buzzword you hear sometimes. And I think it's certainly good for doing research that is just kind of on the pure science side that is just, you know, to kind of satisfy our, our curiosity. But I think it's also a good way to unexpectedly discover new roots for applied research, like in the example of coffee. So I'm a big fan of curiosity. I think I've been able to work on a really eclectic mix of different problems as a faculty member from making more insulating wetsuits to the projects that we've been talking about today to other projects and collaborations I have that are more on the medical side where we're trying to, say, penetrate a bacterial biofilm with active particles.

Jeffrey Moran (42:44)

A lot of these really, the impetus for me, really stems from my curiosity. That's what got me into this self-propelled particles field in the first place. Just that I wasn't really satisfied with the answer that I got in that master's thesis defense. And, you know, I was able to just follow up on it and make it my thesis. So if there's one driving force, it, it would definitely be that just, I'm just a curious person by nature, and I have a hard time shaking off questions that really get under my skin and that I really wanna know more about.

President Gregory Washington (43:13):

No, that's cool. Well, Jeff, there's plenty of room at the bottom.

Jeffrey Moran (43:17)

<laugh> <laugh>. That's exactly right. That's exactly right. So I often invoke that speech <laugh> that, uh, there's plenty,

President Gregory Washington (43:25):

Plenty of room at the bottom.

Jeffrey Moran (43:26):

There is, uh, the, the speech by Richard Feinman in 1959

President Gregory Washington (43:30):

Fineman. That's exactly right.

Jeffrey Moran (43:31)

And in that speech, he talks about swallowing the surgeon. He said, there's a friend of his that said it, it, it would be very interesting in medicine if you could swallow the surgeon that it goes inside the body and, you know, goes to an organ and looks around. And actually later in that speech, he challenged the community to build a tiny motor that fits inside a cube, 1/64th of an inch on its side. And a lot of what we're doing is, is exactly that, is we're really trying. In fact, we could probably fit much smaller than 1/64th of an inch. Some of the particles we work on are too small to even be seen on an optical microscope. So, well, yeah. There's plenty more to do. Yeah.

President Gregory Washington (44:09):

That is really cool. Yeah. Um, that's cool for drug delivery. That's cool. For all types of treatments for disease. So really, really cool stuff.

Jeffrey Moran (44:21):

And I should mention, you know, this has really grown in the last 20 years to a, a robust field in its own right. The first ever startup company that I'm aware of was founded recently by a guy in Spain named Samuel Sanchez, who's kind of one of the superstars of the field. They're looking to develop a better treatment for bladder cancer. Part of it has to do with making particles that use enzymes, nature's catalysts, as the engines, basically. And we have some other projects in the lab that use those very same enzymes partly for, for biofilm eradication or other sorts of applications like that. So it is growing, and I don't know if we're gonna see it, we're not gonna see it in clinics in a year or in five years, or probably not even in 10 years, but maybe in 15 years, right? There are some fundamental challenges that we still have to address. And on the medical side, we haven't really talked about that today, but on the medical side, we're really trying to address, uh, some of those, particularly making them from safe materials.

President Gregory Washington (45:21):

That is cool. As a wrap up here, one of the things that I really, really like about you is that your passion is not just in engineering. It's not just in the sciences. You know, I was happy to see, uh, one day when we had our jazz musician quartet at the house playing music for one of our events to say, wait a minute, that guy looks familiar.

Jeffrey Moran (45:49):

<laugh> Yep. Yep. That's me.

President Gregory Washington (45:49):

And so you, and so you moonlight as a freelance jazz musician. Specializing in the double bass.

Jeffrey Moran (45:55):

That is correct.

President Gregory Washington (45:56)

So talk a little bit about that, how long you've been playing the double bass and what excites you about jazz.

Jeffrey Moran (46:02):

Yeah. Well, I've been playing the bass since I was in sixth grade. So, quite a while, quite a while. But I've been entranced by the double base for as long as I can remember since I was about four, I think I was about four when I started begging my parents to get me an upright bass. And my mom still has some embarrassing photos of me as like a 4-year-old wearing a tuxedo for Halloween. I was a conductor trying to conduct the orchestra, and I can't really say what drew me to the bass. I still can't really fully explain it. And maybe that's part of a, a testament to how powerful it is. I just love the way it sounds. I love the depth, I love the character of a well-struck double bass string, a well-plucked double bass string, you could say. And so I did piano lessons as a kid, like many kids do. Didn't really enjoy them that much, but it really, it, it was useful though because I learned how to read music that way. And, you know, also having a pretty robust interest in math. I, I saw pretty quickly the parallels between music theory and mathematics.

President Gregory Washington (47:14):

Okay. So that was gonna be one of my next questions.

Jeffrey Moran (47:16):

Yeah. Yeah. So <laugh>, but then in the sixth grade, I had the chance to take a music appreciation elective, and there was one day where they just turned us loose to try out different instruments and I made a beeline for the double bass and just haven't really set it down since. In college, in undergrad, I was briefly for about two years, a double major in jazz performance and mechanical engineering. I ended up just sticking with the engineering major. But during that time, I had the chance to study with a jazz bass instructor who really was a fantastic mentor to me, not just as a musician, but just as a, as a young adult. So I think I got what I needed because I realized that you don't need a music degree to play music. But the same is not exactly true for doing engineering work professionally.

Jeffrey Moran (48:08):

So college was when I really started to freelance on the bass. And it ever since has been a creative outlet and it's been something I've been able to continue to do, which I'm really, really happy about. Um, so, so you asked about jazz. You know, we, we had jazz records playing in the house growing up. I was in, you know, classical orchestra in high school. And I still enjoy classical music as well. But I think part of what drew me to jazz was it can be very mathematical, it can be very complex in terms of the harmonies. So I think the mathematical side of me gets really, you know, intellectually stimulated by that. There are a lot of parallels actually between, and that's, this is the great thing about jazz is that it's such a mix of different rhythms, different traditions.

Jeffrey Moran (48:59):

And so there's the, the left brain and the right brain side, right? I think both of those things appeal to me. Of course, the improvisation aspect. Improvisation is a very important part of jazz. So being able to play the same tune night after night after night, but differently each time is another thing that I really enjoy about jazz. So it's really, I think it marries the cerebral with the visceral, you know, because there's a lot of intellectual stuff to appreciate about it, but there's also a lot of rhythm and a lot of groove. And just having that complicated soup-- jazz is such a soup. It's a rich soup together. And I think it, that's

President Gregory Washington (49:42):

Exactly right. That's why I love it. So, last question. So what would you say is the value of the arts in arts education and producing advancements in STEM? Science, technology, engineering, and mathematics.

Jeffrey Moran (49:57):

Yeah. It's really, I think, undervalued. I think I, I kind of like the acronym STEAM you know? science, technology, engineering, arts and mathematics. There's a colleague down the hall from me who has a quote on their door. It's from, uh, Theo Jansen, the Dutch artist. You may be familiar with the Strandbeest. Those mechanisms that look like these big creatures that walk. And he has a quote. It's something like, the walls between art and engineering only exist in our minds, right?

President Gregory Washington (50:27):

I agree with that.

Jeffrey Moran (50:28):

That engineering, I mean, you know this as an engineer yourself, that engineering at its best is a very creative pursuit. Even the pure sciences and mathematics can be creative pursuits as well. And so I would say, I mean, I can speak from my own experience. My main creative artistic outlet has been jazz bass. I think I'm absolutely a more effective and creative engineer for being a musician. It's certainly made me better at giving lectures because that's a performance, right? And so a lot of the same skills from playing jazz bass, like thinking on your feet and reading the crowd and reading their response. That comes in handy when you're giving a lecture too. I'm also a better musician for being a scientist and an, and an engineer because it made me appreciate the complex theory. And when I listen to a Charlie Parker solo, I can appreciate the genius that is on display there.

Jeffrey Moran (51:25):

Right? In a very deep and richly satisfying way that I would not necessarily have if I didn't study jazz theory. Right.

President Gregory Washington (51:33):

Understood.

Jeffrey Moran (51:53):

So for me, I guess maybe the value is in realizing how similar they are, how they're almost two sides of the same coin, you know, and they're just two different ways that I can be myself and be creative and produce things, right? So I think I would exhort everybody listening to this, particularly those who have a bent towards either the arts or towards science to try to explore the other thing too, right? And to start to see kind of the commonalities between them.

President Gregory Washington (52:06):

Outstanding. Outstanding. Well, we're gonna have to leave it there. Jeff Moran, thank you for working towards a cleaner, healthier future for us and for the planet.

Jeffrey Moran (52:20):

Thank you again for the invitation. And uh, it's really a pleasure to be here. And it's a pleasure to be working at Mason and I love it here. So hope to keep doing, hope to keep doing this for a, a very long time. Keep doing good stuff.

President Gregory Washington (52:34):

Alright. I am ����AV President Gregory Washington. Thanks for listening. And tune in next time for more conversations that show why we are All Together, Different.

Outro (52:52):

If you like what you heard on this podcast, go to podcast.gmu.edu for more of Gregory Washington's conversations with the thought leaders, experts, and educators who take on the grand challenges facing our students, graduates, and higher education. That's podcast.gmu.edu.