 Let me tell you about an award that goes out every year to the top scientists and engineers across the U.S. government. It's called the Presidential Early Career Award for Scientists and Engineers, or P-Case. And it embodies the high priority that the government places on maintaining the nation's science leadership by producing outstanding scientists and engineers and nurturing their continued development. The award identifies a cadre of outstanding scientists and engineers who will broadly advance science in the missions important to the participating agencies. The P-Case award is the highest honor bestowed by the U.S. government on outstanding scientists and engineers beginning their independent career. Hi, I'm Dr. Phil Percanti, Director of the U.S. Army Combat Capabilities Development Command's Army Research Laboratory, and you're listening to our podcast, What We Learn Today, and where we talk about the underpinning research that will help build the army of tomorrow. Today, we're joined by one of the newest recipients of the Presidential Early Career Award for Scientists and Engineers, Dr. Nathan Lazarus. Nathan, welcome to the podcast. Thanks so much for having me. So I just wanted to have an opportunity to chat with you, Nathan, about your award and to personally congratulate you on achieving what I view as one of the finest awards you could win early in your career. So congratulations. Thanks so much. It's definitely a great honor. Nathan, I am extraordinarily pleased for you that you're the P-Case winner, but I'm also extraordinarily pleased that something else has happened to you that's pretty major. Can you tell me a little bit about that? So it's kind of amazing when the P-Case is the second most important thing happened to you in a given week, but I actually got married a few days after I was told I would be awarded the P-Case. Congratulations. Thanks so much. That's awesome. Where is your wife from? She's actually, she lives in Rockville, but she's a local vaccine researcher. Oh, she's a researcher too. That's OK. So a perfect match. Yeah, I think it definitely has been a great match and it's definitely a wonderful wedding. So here's the question I have for you because my wife is a teacher. My kids, fortunately, were blessed with two boys who every day when I was home, we made a rule that we all ate dinner together. So our dinner conversations were never about science. What about your dinner conversations? I think it varies, but definitely we do chat a little bit about because she's a chemical engineer by training and I do a lot of work on fluidics. And so definitely I think we do chat a little bit about the kind of, there is some overlap between our backgrounds and everything, particularly the common experiences in grad school and so on and so forth. So yeah, it probably does have a little bit more scientific kind of day to day conversation. So bringing new meaning to interdisciplinary research. Congratulations. So thanks so much. Cool. So now I have to ask you a few questions about your career. So how many years have you been here at ARL? So I've been here a little over seven years now. I was a couple of years as a no-route postdoc and then I've been about five years as a civilian employee. So a postdoc right out of your PhD? That's right, that's right. Where'd you go to school? Carnegie Mellon. Carnegie Mellon. We have several researchers on our staff from Carnegie Mellon. Yeah, my team lead actually, Sarah Bader. She also came out of Carnegie Mellon. So we recruited out of the same advisor there. Same advisor, I know your advisor. I saw your advisor probably three or four months ago. He mentioned Sarah. Now I'm going to have to go back next time I see him. I mentioned that you are a P-case winner. That's very cool. So you're an electrical engineer then. What was your PhD thesis on? So my PhD work, actually very similar to Sarah's, was on MAM's chemical sensors. I actually used a lot of the techniques she developed for fabrication to look at other types of sensors, mostly capacitive sensors for measuring humidity. And upon graduation, you came here and you did a two-year postdoc? Yeah, that I was two years as a postdoc and then converted at the end of that. I liked it so much you decided to stay. Yeah, I think definitely it's a great place to work. And I think it's something that we, I feel like we get a chance to really look at some really difficult problems and a lot of the flexibility to kind of work on those problems. So tell us a little bit about what you're working on. So a lot of my work is focused in an area called stretchable electronics, which is a subset of wearable kind of devices, but primarily trying to make wearable devices that can actually put in close contact with the skin. And the skin, unlike a lot of traditional electronics, is a very soft and very stretchable kind of substrate. And so making particularly things like wearable sensors, wearable actuators to monitor soldier health, monitor kind of soldier emotional state and so on, as well as trying to actually, a lot of my work was in the context of a DARPA program, DARPA Warrior Web, trying to protect joints during, basically during motion. Protect joints, but these are joints that have electronic elements to them? These are... So actually human joints. So one of the main, we think about soldiers getting shot and so on, but the reality is the vast majority of soldier injuries are rolling an ankle, damaging a knee. And so this DARPA Warrior Web program was trying to embed sensors and actuators, basically a soft exoskeleton on the surface of the joint to detect the joint was going some direction it wasn't supposed to and then provide a counteracting force to help protect the joint. But you were developing a sensor. Specifically, I work actually on power systems for these devices. Power systems for the devices, but were they embedded into the soldier or was it? So the program actually was a wearable exoskeleton. So it's not in the soldier, but something more of like a, let's let's picture something more similar to like long underwear type of form factor. And then one of the biggest challenges in stretchable electronics as well in this program is that most traditional work in this field was very low power, like a sensor that might have needed a nanowatt of power. And when you're starting to have these larger systems intended to really actuate and actually provide a counteracting force, suddenly power management became a much more important role. And so my work is specifically stretchable power management. So how do we manage these, the power for these systems to prevent excessive heating, prevent discomfort for the soldier, as well as to use batteries and so on more efficiently. So you need to be able to, when you say stretch, it's way beyond bending. That's right. So what is the difference between stretching, stretchable electronics, flexible electronics, and bendable electronics? I would say the, within the scientific disciplines, flexible is a somewhat broader term. Flexible includes things like particularly materials made of polyamide and PET type of plastic. That bends by let's say less than 5%, type of thing, less than 5% deformation, where a lot of the truly stretchable devices we're talking tends to hundreds of percent strain. And on the surface of the body, the skin in certain parts of the body can stretch by as much as 100%, significantly beyond what you can do with this more traditional flexible electronics. I see, so I would think that the market for this, the commercial market, could be pretty hot, right? I mean, there's a lot of companies, particularly those who make garments, things like that, who are looking to incorporate some sort of electronics, either for sensing or other activities into the garment themselves. But this will be an area ripe for research of your sort. That's right. I mean, the stretchable electronics discipline as a whole is relatively recent. The field mainly originates from a major science paper about 10 years ago, but it is increasingly becoming commercialized, that there are a number of startups, and I think definitely people really can see that vision of, okay, rather than carrying a cell phone, having the cell phone, write a temporary tattoo on your skin or something just right in your t-shirt, that type of thing, I think is real. As you said, there's a potentially massive commercial market, and I think that is definitely where the field is going. Would you consider your work pacing or are you sort of a contemporary of a particular university or a particular company? We would, I guess, be in probably the second generation of stretchable researchers, that the very earliest, I think the, yeah, so the big paper that kind of made the field was about 2011, and so, and I guess I would have started my career in stretchable more like about 2014. So it's not too long after kind of the big seminal work in the field, but we probably would be second generation. Where did the seminal work come from? A professor, John Rogers, then at University of Illinois. And then I actually have a close collaboration with one of his postdocs that wrote the paper, Nanshu Liu, through our ARL South site, looking at trying to use some of my power technologies in her fabrication processes. I see, so what is the difference between the power technology work that you're doing and say the work that, I think Roger's spun off a big company, a pretty big company. Okay, MC10. MC10, so is MC10 still around? MC10 still around, I think it's still considered one of the more successful kind of players in the stretchable space. I mean, not other companies are very old, but it is the biggest player. Right, so what's the big stumbling block to get fairly high power stretchable electronics that you could put on your skin or on a joint or in clothing, what are the stumbling blocks? So one of the biggest ones with a lot of the early technology in the space was that making physical connection was a big challenge, that wires tend to pull out, tend to be broken. So wireless power has been fundamental to these right from the beginning. And using their technology, I think the best they really had shown for wireless power efficiency was about 20% efficiency. And so a lot of my contributions in the space, a lot of the work that I've done was taking that 20% and changing the conductor material, incorporating my nag materials and to bringing up to power efficiencies, I think I've done as high as 92%. So a very, very large improvement in power efficiency. Suddenly, rather than these very low power sensors that have really kind of started hitting in the commercial sector, we can envision something like a radio. We can envision something like an actuation system because the power efficiency is dramatically, dramatically stronger, better. So let me make sure I understand this. So much of what we're considering for flexible electronics, the power is coupled in wirelessly. Yeah, that's right. And what you're describing is the loss of power through inefficiencies, and of course that would be heat or some other dissipation, otherwise dissipation of power elsewhere in the environment around the human. But what you're describing is that loss of that coupling efficiency? I'm actually describing loss in power efficiency. So the inductor was burning up too much power, therefore not enough power was getting to the sensor to wherever you're trying to power with it. So the inductor that's actually in the flexible circuit? I see. So your work has really been to improve the inductor piece of that? Yeah, the coil that's being used for this wireless power transfer. And then you can partner with anybody who's doing wireless or anybody who's doing flexible electronic circuitry in that sense once you get your inductor onto their sensor or whatever. That's right, that power systems in general tend to be, I mean it could be incorporated into any kind of stretchable system for, as you said, for sensing, for communication, for actuation, that my systems in general are more or less agnostic to the output. What was the hardest thing about your experimentation? What were some of the problems you had to overcome? So I'm an electronics engineer and that's a component of, I mean, much of my advances have come from understanding the power engineering aspect. You know, how do you make a good inductor? How do you make a good power circuit? But in particularly in stretchable electronics, it is a very, very multidisciplinary problem. I mean, you have to be able to fabricate it. You have to be able to understand the mechanics of it. And in many cases, those are the more difficult problems to solve that I'm using fairly conventional electron engineering, but I'm doing it with very exotic materials and I'm doing it with very exotic mechanics. And so learning a lot of those kind of basics of these other fields was definitely one of the bigger challenges for advancing the discipline. So what did you do? Did you decide to learn all of that on your own or did you pull together a team, an interdisciplinary team? So we definitely did rely very heavily on experts in mechanics. I mean, I've definitely worked with other colleagues here. There was a colleague, Jeff Sleifer, up at VTD at the time. The Vehicle Technology Director. And Composite Mechanics. He provided a lot of guidance on, and he had had a history of doing some work in stretchable electronics. He provided a lot of assistance. I've had some students in several different, who kind of have been able to kind of take advantage of some of their knowledge and things like materials and mechanics, as well as the team of other researchers within the power components branch. This is kind of the nature, I think, of research today. It's very difficult to stay within your own silo domain and really make big, innovative disruptions. You have to partner with people across multiple different disciplines, oftentimes to solve the problems that we face today. And I think your work is a great example of that. Without pulling together people from other disciplines, your research would not be as far along as it is. And I think all of us are realizing now, and particularly for guys who have been around a while, like me, it took us a while to learn this lesson, but I think as an early career winner, you recognize that right away. And most researchers of your generation recognize that really to be successful, you have to partner. Yeah, I think I definitely agree that collaboration has been very important. I mean, you can't know everything about particularly a very complex discipline, like stretchable electronics, without relying on other people's skills. And then that's definitely been an important part of my career. So where do you see your research going in the future? So one of my priorities is definitely trying to look at 3D printing of stretchable devices as well, trying to make, rather than just a flat patch, printing a glove, printing a sock, something that really is intended to be significantly more complex and taking advantage of a lot of the advances in really fabrication technology, even since when I started in the field five or six years ago. I think the notion of putting flexible sensors on people, it's very compelling. There are many opportunities in the commercial space. I think the Army is still trying to understand as an open question, where one should apply a sensor to a soldier and what the value of the data that's collected actually is for improving the soldier's performance, let's say. And what is the correlation between what's collected and performance? I think those are all open research questions which are part of an even larger community that your work really enables, because if you can't get the power in, then you can't drive whatever sensor you wanna put on a soldier. So your work is critical to being able to even understand a whole plethora really of different questions for usability of sensors on soldiers and even a broader question of sensors on people in the commercial space. Yeah, I think I definitely agree with that, that the Army, as you said, there's a lot of different potential applications. The commercial sector has chosen to focus on medical sensing specifically, which has been a little bit less of an Army challenge. And so the Army, I think we do definitely think things like soldier protection, we think like improving soldier performance are really the likely kind of the killer app or whatever within the more Army kind of application space. What do you think about the soldier protection space? Where do you see application for your research? Oh, so I guess I was referring specifically to things like protecting the joints and so, yeah. So more of this kind of warrior web type of space. Not ballistic protection. I think because these tend to be soft and pliable, probably not necessarily ideal for ballistic protection specifically. That a lot of times ballistic protection tend to make rigid, more rigid substrate or rigid materials where the need for stretchability is less critical. Not only stretchability, but conformability, I would think. So could you conceive of a day where our ballistic protection systems actually have included in them, within them, sensors, to sense fracture, to sense stress and strain. I mean, there could be a day where anything that needs a conformal sensor with wireless power transmitted to it could be enabled by the research that you're doing. That's right, that you can definitely tend to, definitely you could conform these devices to basically an arbitrary form factor very, very easily and certainly I could see it integrated in helmets and armor and so on without any particular challenge. Where does this fail? What's the limit of stretchability or radius of curvature? So generally these, it varies from technology to technology. The work with things like MC-10, they use a technology based on serpentine electrodes where you're basically making something kind of like an accordion that actually unfolds as you stretch it. So conventional conductor unfolding, that goes up to generally, it depends on thickness and geometry but that's usually targeting skin which is again this 30 to 100% strain type of range. The liquid metals that a lot have done with a lot of my career, those can do that very easily but people have shown them up to, I think about 1,000% type of strains where they work very well for working with the human body but they can also be integrated into things like soft robotic actuators. Something like I think a nurse bot is kind of a classic example. Something like the movie Big Hero 6 where you have something soft and basically a much softer, much friendlier robot able to pick up a soldier that's been wounded in the field and get them out of harm's way. I've never seen Big Hero 6 by the way so I don't know what you're talking about. It's basically a big soft kind of stretchable. It actually was inspired by one of the big stretchable specialists a professor at Carnegie Mellon that came after I left there but it is a very good kind of kid's movie if you ever get a chance. But it's a very traditional example of a soft robotic type of environment. Gotcha, so flexible robotics would, I could see where flexible robotics would really need what you're working on. Yeah, because a lot of times there, I mean controls and actuation are really key to working with soft robotics and so having something like a sensor that can conform to a very, very soft actuator is kind of key to that discipline. Did you mention the materials that you're working with? So I think I briefly touched on but I primarily work with room temperature liquid metals. Which metals? So it tends to bring to mind mercury which most people know is very toxic. Yeah, that's why I wanted to ask you that. But the people in the field, particularly something more on the human body know that that's not a suitable selection. And so pretty much everybody in the field that does room temperature liquid metals instead relies on the non-toxic gallium alloys with, and I've worked out with both eutectic gallium indium as well as gallon stand which is gallium indium and tin in the past. Well, I'm really excited about what you're doing. I think that your work has been recognized now outside of ARL across your own community but now across the greater science and technology enterprise that the Department of Defense has. So I'm very, very, very proud of what you've done and I'm very proud that you're still here working for us at ARL to do it. And I encourage you to continue on with your research and I wish you much success. Well, thanks for joining us for what we learned today. In upcoming episodes we'll continue the discussion about the disruptive research that will fundamentally change the army of the future and make American soldiers stronger and safer. As always, science is a journey of discovery and we're glad you're along for the ride. For the Army Research Lab, I'm Dr. Phil Percato.