 So I'm very happy to be here and I'll tell you a little bit about the research that my students are doing on high frequency power converters. So and pretty much a lot of what I'm going to talk about is about power density. Power density is the name of the trade here. Power density is like people want smaller and smaller power supply like everyone complains that it doesn't matter how small your power converter isn't that it's connected to your laptop. You always want something smaller. You can see whether it's a thin path or an iPad. Like that we want smaller and smaller power converters and at some point you're going to want them even smaller. And there's so these are the ones that like both Lenovo and Apple sells right now but there's small companies that have released even smaller more powerful products recently. So this is these two were both recently released. This is Fensics and this is Salt. That they have released 65 watts converters that you can use to power your laptop and also like perhaps charging your phone with something that is significantly smaller than a similar offerings in this kind of like power converter levels but still we want smaller. So one of the things I want to break your bubble is that like several times people have asked me like so if we can keep making the power converter smaller and smaller can at some point put it inside your laptop. So you don't have a power converter. There is no you can't and that has more much to do for safety as if you were to put that converter inside your laptop, you need to have wires that are carrying 120 volts very close to your legs and probably people won't be very feel very comfortable about that. So now usually we need to put them a little far away but has nothing to do with the technology has to do with safety. But anyway, but power density is the name of the game. And unfortunately it's something that is very actually hard to specify because depends heavily, very heavily on applications. So here I showed two completely different examples of what are considered up to a few years ago state of the art in power density. So here this is a AC motor that has externally high power density of 75 kilowatts per liter and a similar and a power factor correction three phase for this completely different application. That the most we can do is about 10 kilowatts per liter. And how much you can do for achieving power density to convert electric power from one form to another really depends on application. And it may be straightforward to think it's something easy to get. It turns out it is not. It's not simply a saying we need this much. We're processing these many watts in a certain amount of volume because unfortunately this is something that is victim of marketing. So for example, this is a couple of power supplies that are commercially available you can go online and buy them. So this is one from General Electric that has a power density of around 18 watts per cubic inch and it's pretty standard. This is for power servers and it's a universal converter. Not very exciting. You see that it consists of a printed circuit board and a bunch of components on top. Similarly, if you're willing to pay a lot more money you get also from GE. This is slightly more efficient converter that can achieve a quite respectable 24 watts per cubic inch. To give you kind of an example of the power density of this converter, this is about 32 watts per cubic inch. So, but I mean it's definitely more expensive and they're rated for different environments. It's really hard to compare when we stand in power density. So some companies build DC-DC converter that had like just compare the order like this is 1.3 kilowatts per cubic inch. It's a power converter that like this company, Bicor makes. What it makes it hard to compare against is like this only does DC-DC conversion. And in order to make this regulated, you probably need to add a lot of more blocks and probably some other capacitors. That's why you take everything into account. This number probably is gonna come down quite a lot. But I mean for marketing purposes, this is a great number. Kind of like to show how it's a victim of marketing. The same company, Bicor, probably different team design another circuit that only achieved seven watts per cubic inch, right? So I think this guy should talk to these guys. But I'm not saying this is good or bad. It's just like it's something that we all want power density. It's just that we don't know what that means. It's a very nebulous number. And I'm just gonna keep it that. I'm not gonna make it more concrete. It's gonna be still a nebulous number. But I'm just emphasizing the fact we just want power density. It's easier to transport, to move, to have portable applications if we have power converters that are smaller and use less amount of volume or material. So how can we improve that tenuous number? So the trick in what we do in research for power electronics, you can either go having better materials that I don't do. That's the job for the people that does material science, to make more efficient, lighter components. Or what we can do from a circuit perspective that is kind of like my area of expertise is increase switching frequency. So all these converters, like any power adapter that you open up, you'll see that it consists of a very limited number of ingredients. You have usually a printed circuit board. You have inductors. You have capacitors, some semiconductors, and heat sinks. That's pretty much about it. And it turns out that the semiconductors, we use them mostly as switches. We turn them on and off, as if it was like mechanical switches. But we do it very, very fast. And it turns out that the size of all the other components, inductors and capacitor, actually the size and the amount of energy they need to store varies inversely with the switching frequency, which means that at least in a very, very simple way, if you were to operate the switches in this converter ten times faster, at least nominally you would be able to reduce the size of the inductors and capacitors by a factor of ten. So that's pretty much the recipe of what we need to do to increase the power density, is just use the switches and switch them on and off as freaking fast as you can. But you can imagine that that may have some issues, just because things are not necessarily ideal. So particularly the semiconductors. The switches that we're trying to turn on and off as fast as we possibly can, are not ideal. It takes times for them to turn on and off. And during the time, that transition time, you generate some loss that prevents you from achieving high efficiency. But we can improve this by having better semiconductors. Like recently, and I'm gonna show you a couple of slides on that. There's been very new semiconductors, it's called wide band gap semiconductors like silicon carbide and gallium nitride. That allows us to operate several times faster than what you probably can find now in today's many converters today. Another issue that is very hard to improve upon is better heat sinks. It's very difficult to extract heat from small components. So this is one of the disadvantage of trying to, when people want things smaller and smaller and smaller. In order to be able to achieve smaller higher power densities, we also have to operate with higher efficiency. Because as things become smaller, we reduce the surface area that we can extract heat off. And at some point, things just either have to operate at much higher temperature, or we need to operate much more efficiently. So to show you kind of like where the state of the art is and where things are heading, I wanna show you these converters that Professor Kolar in ETH published a couple of years ago, several years ago already. That shows how the power density improves as we increase the switching frequency in converters. So for example, in this converter, all of them have the same kind of like matrix. So this converter has switches operating at 72 kilohertz and achieves a density of around 4.5 kilowatts per liter. So you can see that as I showed you before that as you increase the switching frequency, we can reduce, we can improve the power density and reduce the size of the converter. So if you go to 250 kilohertz, you see that now we have a 10 kilowatts per liter power density, which is kind of great. So let's just keep going. So if we double the frequency to 500 kilohertz, you can see that the power density now goes to 13 kilowatts per liter. But notice that something is happening as we keep increasing the frequency. Because the devices are not ideal, what's happening is like the benefit that we're getting by switching at higher and higher frequencies is not keeping up, right? So we doubled the frequency but we didn't double the power density, right? So if we do this again, if we go from 500 kilohertz, double the frequency again to 1 megahertz of switching frequency. You notice that the power density only goes to 14 kilowatts per liter, right? So it kind of makes it questionable that if we double the power density, the switching frequency again, whether the power density will improve in any meaningful way. And it turns out that that's kind of where things are, right? So all these converters use silicon semiconductors. But by switching to a better newer semiconductor like white-band gap devices, it turns out that you can do much better. But it's been predicted that as the power density that is expected, that different converters are gonna achieve as we progress on time. You can see that because of the non-idealities of the semiconductors and the inductors and the capacitors. There's gonna be a plateau of power density that essentially is gonna put a limit of how small we can make power converters. Think of this as Moore's law for power converters, right? So, but fortunately, there's been a lot of investment in semiconductors. And the original power converters that we all know and love use silicon devices. But there's not newer white-band gap materials like silicon, carbon, and gallium nitride that has a much larger band gap, which means that they can operate much faster. And also have, in the case of silicon carbide, much better thermal conductivity. Which means that you can extract heat much more effectively. So having a wider energy, a wider band gap, means that you can make power, semiconductor devices that can operate at higher voltages and operate at higher temperatures. By having higher electron saturation velocity, these devices, silicon, carbon, and gallium nitride can operate at much higher frequencies. And also in case of the particular silicon carbide, you can actually cool them much better. So these are the two available white-band gap devices that we are starting to see commercially. But I mean, I guess the holy grail of white-band gap semiconductor is the development of diamond semiconductors. So diamond semiconductors, they're still not commercial devices that I am aware of. But they really outshine all the other white-band gap devices that are available. It's just unclear when, hopefully within my career, I'll be able to see some of these devices. They should be able to operate at higher frequencies. You can cool them much, much better and operate them at much higher voltages and they're going to be pretty darn expensive. But hopefully. But that's not what I do. This is, I guess this is the same data is represented in a different way in which you can see what most of the numbers that have been available in power electronics that use silicon devices and where gallium nitride and silicon carbide compare against those devices in terms of the switching frequency that they can operate at, the temperature and the voltage that they can operate at. So the advent of white-band gap semiconductors really promises a lot of benefits in power electronics. But that's unfortunately not enough. It turns out that in power electronics, having better semiconductors is not sufficient to have smaller power converters. It turns out that when you see the roadmaps for companies in the utilization of silicon carbide and gallium nitride, they tend to put these devices replacing applications that you can currently have with silicon devices. So for example, this is a plot that I think is from Panasonic that shows on the horizontal axis the switching frequency, the operating switching frequency. And in the vertical axis, the amount of instantaneous, the switching power that these devices can achieve. And they have different types of power semiconductors. And then on top of it, they show the areas in which they can find this new gallium nitride and silicon carbide will find application. But notice that they're essentially just replacing silicon devices at the same operating frequencies just with a different device. And that's not enough to make the converter significantly better. This is another roadmap that you can find online that shows the frequency space in which silicon devices can operate at. So you can operate them at a few hundreds of kilohertz and have power levels in the few hundreds of kilowatts. And if you start using silicon carbide devices, you can significantly extend the power handling capabilities of your power converters, mostly because the silicon carbide devices can operate at much higher voltages. And similarly, gallium nitride devices are targeted for applications that should be able to operate at much higher frequencies. Because they have higher mobility than silicon. And so we're expecting to see that in lower voltages, but higher frequencies, whenever you need applications like that, you can start thinking about using gallium nitride devices. But still, these are very small increments of what you can actually achieve by implementing clever circuit techniques, which is what my research group is doing. Particularly, what I think has to happen in order to improve the power density is actually cramp cop the frequency a lot more. Not a tiny bit more, but a lot more. And I'll explain why is that. As I mentioned, one of the components that a lot of the power converters require is inductors. And if you remember your first electrical engineering classes and circuit classes when you look at inductors, an inductor is usually a magnetic material, a magnetic core, in which you wind a couple of wires around it. And that's how you make an inductor. And unfortunately, the magnetic material incur in very large losses as you try to increase the switching frequency. And that's shown in this green curve here. As we increase the switching frequency of power converter nowadays from a few tens of kilohertz to several hundreds of kilohertz, we see that on this axis, I'm showing the power density of a converter. We can, as I mentioned, as we increase the power density, the switching frequency, we also increase the power density of a power electronics converter. But as I mentioned, I show you those examples before. When we reach a frequency of a few hundreds of kilohertz, probably up to a megahertz, we see that we reach a point of diminishing returns, in which we're not increasing the power density anymore, mostly because we have switching losses in the semiconductor. But most importantly, it's the magnetic, the losses in the magnetic components that are getting just way too hot that prevents us from switching even faster. So the solution that people do nowadays is when your magnetic core gets too hot, you just get a bigger one. If you get a bigger magnetic core, that means that you cannot make the power supply smaller. And you find yourself in this curve that as you keep increasing switching frequency, you are not improving your power density any longer. But what my group has been proposing for a couple of years now is that once you read a switching frequency of few megahertz, it turns out that because it's fundamental that the size of the inductors that you need becomes smaller and smaller and smaller, it turns out that once you reach this frequency, you can actually start making inductors that have no magnetic core at all. Essentially, you can use a piece of wire, make a couple of turns with it, and that's your inductor. You completely eliminate the magnetic material. But when you do that, you're gonna be penalizing power density because now you don't have a magnetic core. There's a reason people want magnetic cores, right? But because it still holds true that as you keep increasing the switching frequency, the size of inductors becomes smaller, it turns out that you can actually just, if you crank up the switching frequency about an order of magnitude or more, you can actually come back when you're operating in few tens of megahertz, you can actually gain back all the power density that you lost by eliminating the magnetic core. But this also opens the door for new applications and I'm gonna try to show what we can do with that. So I mentioned that like one of the issues, one of the reasons converters generally do not operate at very high frequency is switching loss. So this is a particular topology in power converters and here on the right, I'm plotting the voltage and current across this MOSFET that as I said before, I'm operating as a switch. I'm turning it on and off so the current has certain value or zero most of the time. But I say that unfortunately there is an overlap because the MOSFET is not an ideal device. It takes some finite time to turn on and off. This results in an overlap of voltage and current across the switch that results in instantaneous energy loss that like translates into power loss. In switching power loss in your device. So this pink area here is this overlap of voltage and current that when you get the average that the average power loss in your device that results in heating in your device and loss of efficiency. But notice because this happens every time you turn on and off this MOSFET, if you double the frequency this loss component will happen twice as often. And hence you just keep increasing your switching loss. So what my research group does is we're investigating other type of switching strategies that try to eliminate this overlap. And we can do that by being clever about how we design circuits. So what we do is we use resonant switching topologies which that means we have topologies that use a lot of inductors and capacitors. We love inductors and capacitors. And very complicated differential equations that you can solve in ways that you can set the voltage across the switch that it naturally on its own rings very smoothly up and down such that at the time you have to turn the switch on you avoid having any overlap of voltage and current when you have to turn the switch on. This type of topologies completely eliminate this switching loss that many semiconductors present but it comes at the expense of higher stresses in your semiconductor. You probably need semiconductors that requires higher voltages that have to be able to withstand higher voltages. But that's okay because now we have silicon carbide and gallium nitride devices that we can take advantage of. So particularly in my group we've been working with topologies that by increasing the complexity of the order, the dynamic order of the circuit we can actually achieve the same but having much lower device stresses which means that we can have much smaller semiconductors that withstand lower voltages which tend to be better. And so this is kind of like what we're doing from a topology perspective. From a component perspective I mentioned that like a lot of the work that we do is operating at frequencies that allows us to eliminate the magnetic core. That's important because so for example this is one of the inductors for one of the converters that I built when I was in grad school. And essentially it's just a piece of plastic in which we just wind a wire around it to make an inductor. And it turns out that that's an effective way to make inductors at these frequencies because it's very light. But like now there's no magnetic component so which means that you don't suffer from the temperature limitations of inductors that the inductor suffers nowadays. Which means that you can operate this converter at much higher temperatures. And that also offers opportunities for newer applications. But by being clever about how we make these air core inductors we can actually play with the geometry and instead of forming a solenoid we can instead wind our inductor around a toroid to actually constrain the magnetic field to be within the torus to prevent having issues with electromagnetic interference. But we take this even higher because like now we're implementing inductors that do not have magnetic material which means that the only thing that we need is actually a printed circuit board and we can implement the same components just by simple traces on a printed circuit board. So essentially what we're trying to do is instead of having a converter in which you have to put on top of it inductors and capacitors we can simply just print traces on your printed circuit board and make a power converter out of. And there's really nice opportunities of applications that we can do. So for example this is a converter that I built like 10 years ago already and these are a couple of converters that like my students have recently built and like they're moving us closer to essentially have the ability to essentially print a converter. So you just send a converter to a PCB board manufacturer and like they essentially make all your inductors in your capacitors as part of the printed process that you just automatically become your power converter. And essentially what we're trying to do is be able to make our inductors, transformers and capacitors to be essentially simple traces on a printed circuit board that actually located in the inner layers of a board such that we can let the top and bottom layers to be full ground planes that will serve as Faraday shields and hit things such that essentially we eliminate all the physical components that you really need today to make a power converter. So in order to show you an example of this this is a converter that my students put together about a year ago that essentially shows a converter that operates that delivers 320 watts and it's nothing more than traces on a PCB that it only has two capacitors and input and output capacitors that are actually physical devices and a gallium nitride semiconductor and a silicon carbide diode and the rest of the components are simple traces and this converter operates very efficiently. It's very lightweight and hopefully it'll be very cheap because you don't have many components, right? So how can we use these devices? And this is like one area that my students and I are very excited about because we think that there's a very cool applications opportunities. Particularly, I mentioned, I showed you some examples of power converters that you can buy commercially that have achieved externally high power densities. So for example, this converter achieves a power density for around 2.7 kilowatts per cubic inch very high efficiencies and when it takes the voltage from a relatively high input voltage, 400 volts, down to 50 volts. It turns out that like my peers having very effective and designing power converters that bring voltage down very effectively, very efficiently in small volumes. We have converters efficiencies that are in the upper 90s and very externally high power densities. But when we go in the other side of the spectrum, when we want to look into applications that take voltages from a low voltage to a higher voltage, it turns out that we haven't done that well. So let me show you a commercial high voltage power supply, the type of high voltage power supply that you use in scientific equipment, x-rays and satellites. And when you look at converters that go, in this case, for example, from 30 volts to two kilovolts in voltage conversion, you find that the power density that is achieved commercially is only in the single digits of watts per cubic inch. That's kind of pathetic if you think about that when we go down in voltage, the power density is in the kilowatts per cubic inch. When we go up in voltage, the power density is in the single digits and the efficiencies is in the 60s. So a lot of the work that my students and I have been doing is try to see why this is the case and how we can improve upon it. So what we found is that many of the topologies that are regularly used for high voltage conversion are based on ancient circuits that were exploring the 30s and the Walton-Cockruff multiplier, for example, that has limits in the number of stages that you can put together and limits how much voltage gain you can achieve. So as part of my students' work, we went exploring different ways to achieve high voltage conversion very efficiently to try to see and apply it to new applications. So a lot of the converters that we built consist of have these three different stages. They consist of an inverter that takes a DC input voltage and convert it into an AC signal, usually at very high frequencies. We have a rectifier that takes an AC signal and breaks it down to DC of a different level. And usually this rectifier and an inverter, they don't like to operate with the same load. So you need some sort of transformation in stage that lets them talk and operate nicely. So when you look into how one of the circuits looked like we presented this converter a couple of years ago that takes 40 volts as an input voltage and delivers 500 volts at a high frequency very, very effectively. And this is the DC to RF section that takes DC to a high frequency AC. And this is the rectifier that I'm gonna zoom in a little bit. So right now when you think about high voltage conversion, usually people tend to refer to transformers. Like you just look outside and you see a transformer that like it's connected from a power plant that takes a relatively low voltages and you by using the turn ratio of the transformer you can achieve very high voltages for transmission purposes. But that is very effective at low frequencies, 60 Hertz in utility case. But when you operate at very high frequencies it turns out that making transformers is very lossy. It's very complicated. So what we're trying to do is avoid that altogether. It turns out that when we're operating at high enough frequencies we can actually achieve the isolation that a transformer let you have by actually simply using capacitors. This is a trick that you can do at any frequency. It's just that at lower frequencies the capacitors that you need for this to be effective tend to be huge. It's only when you achieve switching frequencies in the tens of megahertz that these capacitors start becoming manageable. And like the nice thing about this is that by using capacitive isolation what we can do is be able to connect the output of many, many converters as many as we want. We can cascade them at the output while the input are connected in parallel to achieve much larger level of conversions that you can do using transformers. So let me show you an example. So this is a converter that one of my students presented early last year that takes 40 volts input and delivers two kilowatts and cascades the output of 12 converters that are capacitively isolated in the way I show you. What this allows us to do is we achieve a large conversion ratio from 40 volts to two kilovolts in a very small volume. This is something I would JB. And actually quite efficiently. This achieves an efficiency of around 92% when we're talking about DC-DC for 100 watts output. But what is external of this type of converter is how fast it is. So because of the switching frequency we can actually, so here I'm showing the output of this converter. So here the converter is off, right? And then we just like turn it on and we reach two kilovolts and we reach two kilovolts within a couple of microseconds. So we can go from zero to 2KV in about a microsecond, give or take. And then we can keep the converter on for as long as we want and we can turn it off. And this is something that because of the switching frequency we can do with this type of converters but if you were to buy any high voltage converter you probably wouldn't be able to do. And why would we want to do that? And this is a very interesting application that we've been exploring thanks to the Tomcat Center for Sustainability that supported us on this work. Like imagine that you have a stainless steel pipe, right? And then you put a gap in it to form electrodes. And then this is just to insulate these two parts. Then imagine that you have water flowing through this pipe but that water contains bacteria. So what we're gonna do is we're gonna apply those very sharp voltages that we are applying by using our converter because when you apply very high voltages across bacteria, bacteria tend to die. Essentially what we're trying to do is we apply an electric field that reaches between 20 to 50 KV per centimeters and when you do that like the bacteria explode. And it turns out that this is a very effective way to achieve pasteurization without having to heat a liquid. So right now when you think of pasteurization would you imagine like heating a liquid very quickly to a high temperature and then to cool it down to try to save, to not alter the flavor of things very much. But it turns out that this is actually more effective. This is a process that is non-termal so you can kill bacteria without increasing the temperature of the liquid. So in theory it shouldn't change the flavor of the things you pasteurize much. It's more effective like when you use thermal pasteurization you tend to kill the bacteria as a side effect. So the energy that you're putting in the liquid is such that like you're starting to disturb the biology of the cells. Here you are directly applying the pulses, these high voltage pulses across the bacteria and then you just blast them away. And this has been prove effective for pasteurization of foodstuffs but also for extraction of oil in algae and also for waste water treatment. And I wish I had come up with this. This is something that has been explored for several years now. And there's a company in the East Coast called Diversified Technologies that makes this system commercially to treat water in this way. But this is the smallest thing that they sell. So this is a unit that costs about $200,000. This is the lab unit. And it's used to pulse electric field through it, liquids and food stuff. So what my students wanted to explore, if we see, we can take advantage of the high frequency circuits that we build to build smaller systems and find really cool applications for it. So we build a tiny version for this system. Essentially, we build a converter. We thought about making something about the size of a breda filter that you can connect to your tap. And as water passes through, we have a couple of electrodes that are separated a couple of millimeters. And we can apply the output of our converter and these very fast pulses to kill bacteria as the water passes through. And it turns out that it works really well. So we actually got a fish tank in my lab and we let it get a little green. And then when we take a sample, we can culture the bacteria to see the amount of E. coli and coliform that we are able to, that this water has. And then we pass this liquid through our electrode system and it just kills the bacteria away. It doesn't change the color by the way, it still looks green. So no, I won't drink it. But it achieves very significant reduction in bacterial levels and essentially it render the bacteria inert. And it requires a very small amount of energy. So thanks to the support of the Tomcat Center for Sustainability, my students were actually wanted to take this idea even further. Because even though we like the idea of being able to use circuits to clean water, to pasteurize water, we realize that there's a lot of competition in that market, right? You can imagine that for example, you can use UV light to clean water, you go to RAI and buy one of these filters, UV lamps to clean water when you go camping or you can just use reverse osmosis or even something cheaper, just add a couple of drops of chlorine and that's it, right? So we realize that probably Waternand was not the best market for this kind of stuff. So we were looking for other markets and what the students realized thanks with some collaboration with the business school, it turns out to be milk, right? It turns out that about 40% of the milk that is produced in rural places gets spoiled before it reaches a distribution channel. So you can imagine that like some guy has a cow, it milks his cow or her cow. And then it takes the milk to the village nearby and because of temperature, weather conditions, road conditions, there's a high probability that some of that milk gets spoiled. About 40% of it and it just has to be thrown away, right? So we thought maybe it's possible to actually build something the size of a bread of filter that is sitting next to the cow to essentially like pasteurize on site the milk such that to reduce the bacteria content in the milk enough so that the farmer has longer time to take their product into market. So we thought it was the greatest idea ever but then realized that physics intervened. So it turns out that milk is about 300 times more electric conductive than water. So that means that our tiny little conveyor that we built which is not juicy enough to treat the, so we have to actually scale our design up. So we had to build a different circuit but it's able to give two kilowatts of instantaneous electric power at the same two kilovolts level in a relatively small fraction, in a small volume. So just to show you how fast we can achieve the two kilovolts level, when we turn on the conveyor, we achieve two kilowatts within three microseconds, right? This is important because we're applying the electric power directly across the liquid. And I don't know if your mom told you not to do that. If you do it for too long, you just vaporize the liquid. And so if you want to use this technique, you just have to apply pulses that are only a few microseconds long such to avoid heating the liquid. So you're gonna kill bacteria but by burning everything around. So we build this two kilowatt system in a way that is effective for treating milk, milk posterization, and that's kind of what we're being testing. So this is the conveyor that we're building. And it turns out that you can actually buy raw milk in the farmer's market sometimes. So we put a little pump and then we just like treat the milk. We apply a couple of pulses and we send it for testing to, and we demonstrated like with only a couple of pulses, we can reduce the bacteria content by log three. It's still not enough for human consumption but we're just testing what we can do with this. But like the temperature doesn't increase significantly at all in this time, Cumbura. Okay, so and lastly the other work that I wanted to show you that my students have been working on is on satellite power supplies. Just familiar with these gigantic satellites that cost billions of dollars. It turns out that there's a lot of companies that are starting to explore what you can do with smaller satellites. So this is what you can do with big satellites but this is what you can do with small satellites. Small satellite you can actually see wider areas not with high resolution with enough to monitor disaster, natural movements, etc. But one of the problems of using small satellites is that right now there's not enough space in the satellite to add propulsion which means that once you put your satellite in space it just like falls back in after a few months. So there's a lot of interest to try to be able to maintain those satellites in orbit. And also like sometimes when you release small satellites they are usually a secondary load in a bigger satellite. So usually the rocket provider dumps your satellite somewhere which is not precisely the place you want it or at the orbit that you want it to be at. So there's a lot of interest to be able to correct the orbits or change the orbits that you're operating at. So you guys probably familiar have heard about iron thrusters that are used in the satellites that are exploring the solar systems but again these are systems that are gigantic. So some of the work that we've been collaborating with Professor Capelli in mechanical engineering is to try to develop something that is called a Helicon double layer plasma thruster that allows us to have very, very efficient a satellite thruster in a very small fraction of the volume. So in order to do that and we supported the Precord Institute we actually we've been evaluating using 3D printer, 3D printing technologies to develop tiny, very lightweight air core inductors that we can use to build these CubeSight satellite thrusters. So and this is an example of one of these thrusters. So this is a thruster for a CubeSight that we're developing that only weights five grams and is able to deliver 50 watts of RF power that is capable enough to strike the Helicon double layer plasma that we can use for a CubeSight. And the whole system we expect to have a thrust in the million unit range and significantly without you and we can fit in a CubeSight. So this is, students get really excited when they start working on satellite stuff. It's pretty cool. And just lastly, it turned out that we became very good at making plasmas. So we've been evaluating using plasmas for medicine. So like the Max Black Institute for example developed a therapy that uses plasma to kill bacteria on tissue. It turns out that bacteria cannot build resistance when you kill it using plasma. So my students put together a small convert that they can use to, essentially it's a similar convert that the one I showed you before but oriented to building atmospheric pressure plasmas to, and so they develop a gun that is about the size, I mean it's a quarter and they can use it to kill bacteria on skin. So my students recently got a grant with the med school here to try to develop this into a commercial product for using plasmas for medicine. And with that, thank you. Thanks very much Juan. We have time for a couple of questions actually for me as a former aerospace guy. So I started my career there. If we had this technology, then we would have rethought everything we were doing at that point. I did flight mechanics, really revolutionary. Any questions from the audience? This is a little bit technical, but you made it very fascinating from my point of view. Any questions, student questions, logical engineer rooms, conversation? Any questions? Yeah, you know, I wanted to slide this way back at your, in person, and it should be later than your ex-partner. Yeah, fine, I'll do it soon. So one of the things that we found is that when we're exploring using silicon carbide devices at high frequencies, it turns out that it's still an immature technology. So we identify a loss mechanism that is not captured in the models provided by the semiconductor companies. So the rectifiers are particularly lossy. And it's not fundamental. I think it has to do with trap charges in the wide-band gap semiconductor. And that should get better over time as people understand how to do the material processing. But right now, they're bad. Looks like we have a two-finger question, five-finger question. What is the application of kind of what you're typically doctored for? You doctored it to a very neutral size and you do so a lot to be in the war. So one of the areas that I've been very interested would be for borehole converters, like things get really, really hot, or also for like, neutral emissions for... Nuclear magnetic resonance. Exactly. Actually, that's the last slide that I was able to show. It's like we can make this type of converters amenable to operate in an MRI machine because they do not suffer from saturation as we don't have magnetic material. Great. Well, thanks, Ken. One final. All right.