 Welcome to Think Tech on Spectrum OC16, Hawaii's weekly newscast on things in matter-to-tech and Hawaii. I'm Jay Fidel. And I'm Cynthia Sinclair. And I'll show this time, we'll go to the Science Cafe and take a look at the field of microfluidics. I'm going to ask, what can microfluidics do for you? Aaron Otai, UH Professor of Electrical Engineering was there. Microfluidics is his field, and he told us about it that evening. Microfluidics is a science of precisely manipulating and controlling fluids in very small amounts that are geometrically constrained in channels with very small, typically sub-millimeter dimensions, a scale where capillary penetration, as they say, governs mass transport. The behavior of such small amounts of fluid is very different than what we experience with liquids in our daily lives, such as when we wash our hands. Microfluidics is a high-tech multidisciplinary field at the intersection of engineering, physics, chemistry, biochemistry, nanotechnology, and biotechnology. In microfluidic systems, fluids are transported mixed, separated, or somehow otherwise processed. The applications of these systems can rely on passive fluid control using capillary forces. Research in microfluidics has been going on since the 1980s. That research has been found useful for systems in which small amounts of fluids are processed to achieve multiplexing, automation, and high throughput screening. In fact, it has been applied in fields all the way from healthcare and medicine to consumer electronics, and it has been used in the development of inkjet printheads, DNA chips, lab-on-a-chip technology, micropropulsion, and micro-thermal technologies. The technologies that are normally carried out in a lab are now often miniaturized on a single chip in order to reduce the amount of the fluid required and the dimensions of the channels involved, thus enhancing the mobility and efficiency of the process. In some of these applications, external actuation is used to transport the fluids. One example is where rotary drives are deployed to apply centrifugal force to transport fluid on a passive chip. The term active microfluidics refers to the manipulation of the fluid by micro-components, such as micro-pumps or micro-valves. Micro-pumps drive the fluid in a continuous flow or for specific dosing. Micro-valves control the direction and movement of the flow. All in all, this is pretty interesting cutting-edge stuff, and it's something we need to know about. As a professor of electrical engineering at the College of Engineering at UH Manoa, Dr. Oda's research encompasses microfluidics as well as the related field of micro-electromechanical systems, MEMS, for a variety of important applications. He received his bachelor's in science from the University of Hawaii at Manoa in 2003. He got his master's in science from UCLA in 2004 and his PhD from UC Berkeley in 2008, all in electrical engineering. He joined the faculty at UH Manoa in 2009. He is the principal investigator for the UH Micro Devices and Micro-Pluidics Lab, the director of the UH Vertically Integrated Projects Program, the advisor for the Micro-Robotics VIP X96 Project, and the faculty advisor for the IEEE Student Branch. His research interests include the design, fabrication, and application of microfibricated devices, including MEMS, biomedical micro-devices, microfluidics, optofluidics, and reconfigurable electronics. The Science Cafe, associated with the Hawaii Academy of Science, meets monthly at the Hasser Bistro downtown. Here are some of the remarks Dr. Oda presented to the attendees at the June meeting. What I'm going to talk about today is an area of research that my lab is involved in, called microfluidics, and I'm going to talk a little bit about what that means and then some applications and areas in which it could affect your lives and how that relates to some research that's going on both in the College of Engineering and also in my lab. So micro, you know, that's the prefix for microfluidics and it kind of defines the kinds of fluids we're talking about. This is our size to the closest power of 10 of a meter, so maybe, you know, a kid or something like that on the smaller side. And normally, in our day-to-day lives, we interact with things that are a few length scales larger than us, like cars, buses, planes, and also a few length scales smaller than us. So for example, insects, things like that. You know, insects, you know, small ones will be on the order of a few millimeters. Once you go smaller than that, then it starts getting hard to see things without microscopes and other equipment like that. And the edge of that is a tenth of a millimeter or a hundred micrometers, and this is the starting of what we call the micro scale range. So this is about the width of a human hair inside of that micro range, the cells in your body are around 10 microns to one micron in diameter. Bacteria are about a micron or a little bit smaller than a micron, and so that gives you an idea of why you would want to look at things in that micro scale range. Because it includes objects that make up your body as well as these pathogens that can affect the cells in your body. Once you go to a tenth of a micron, then you enter a new range called the nanorange or nanoscale range. Those things that would be naturally occurring in that range would be things like viruses. And then once you go below a nanometer, tenth of a nanometer, then we're really talking about atomic scale. There's not only these naturally occurring components in these size ranges, but as engineers we can make things that fall in these size ranges. So for the micro scale range, an example would be optical fibers. So all the fiber optic lines that carry all your internet traffic, the cable itself is relatively large because there's a lot of protective layers and to give it some structural integrity. But if you look at the part of that optical fiber that actually carries the light, it's about 10 microns. So it's in the micro scale range and that's something that's obviously man-made. The microfluidic systems that I'm talking about also have features in this micro scale range. And we can also make things that are smaller than that in the nanoscale range. And this is normally what people term as nanotechnology. So anyone that has a phone, the processor in your phone has transistors in it that have sizes in this nanoscale range. As we make things smaller and smaller, the way that those objects interact with the world changes a little bit. And it's not the same as the way we interact with the world. So this is kind of a thought experiment. Don't read into it too deeply, but just think about how an ant experiences the world versus the human. And there's a few categories here. So for example, strength, ants can lift about 10 times their body weight. People usually, it's more in the order of their own body weight. Ants don't use tools. That's why I said don't read too deeply into this because they shouldn't be able to use tools, but we can use them. Ants can, their insides can cook very easily. We instead use heat to cook our food. Same thing with water. The way that the ants interact with water is quite different from us. You know, a rainstorm can be a catastrophic event for an ant or an insect. The question that I pose to you is why is the way that we interact with the world so different between an ant and a human? Let's say we took an ant and we had this magic ray that made them human size and also gave them some human abilities. Would they still have all these properties? So if I made a human-sized ant, would it still be able to lift 10 times its body weight? Would it now be able to use tools if we magically made it smarter too? Or if we took a human and shrunk down that human, now do they have the properties of an ant? If I took one of you and shrunk you down to an ant size, you would start to have similar problems to an ant. Okay, you would not be able to go swimming. And that's because of the important physical mechanisms that dominate at each of these different sizes. This is showing length scale in logarithmic scale. This is force. If you take a force that depends on mass, like gravity, this is how that force will scale as you make an object smaller. So it's going to decrease on this log-log scale with a slope of 3. So it's a very rapid decrease in a force like gravity that depends on the mass of an object. This blue line represents surface forces. These are things like surface tension. And it has a smaller slope, so that means that this force is decreasing as the size decreases, but it's decreasing much less rapidly. Let's look where we are in the length scale. We're at about a meter at this point here. So if you extrapolate up to where it intersects these lines, we would be very high on this line that represents forces that depend on mass. Forces that depend on mass would be much, much stronger than any force that depends on a surface, like surface tension. And that matches with what we see in our everyday lives. There comes a point where if you follow this red line and this blue line, that both forces are about the same amount of strength. And that occurs right around here. So this is 10 to the minus 3 meter, so that's 1 millimeter. And anything smaller than a millimeter, the surface forces now become more important than forces based on mass. They become relatively stronger. So for a micro scale object, surface tension becomes more important to that object instead of gravity. To kind of summarize that graph in words if you don't like the graph, when the objects are really tiny, you don't really care about gravity anymore. Things like inertia that depend on mass aren't that important. But what's more important are things like surface tension and various other forces. But the stuff I'm going to be talking about today is mostly going to use surface tension. And an example of that that I thought was appropriate to this venue is if you have wine and you swirl it around, you can see that there's some tracks of liquid that are left. That's an example of surface tension. Because what's happening is that the liquid right at the edge of the glass where the liquid is touching the glass, the water likes to stick to the edge of your glass. If you were to zoom in on the edge of your glass, the water is curving up a little bit. That's providing a little bit more area for the alcohol to evaporate. And so the alcohol is evaporating a little bit faster at the edge of your glass. Alcohol also has a lower surface tension than water. So it's creating right at the edge of your glass, you're creating a ring of higher surface tension right around the edge of your glass that pulls up the liquid against the force of gravity. Eventually, once that liquid is pulled up high enough, gravity takes over again and it starts pulling it back down. And that leaves behind these tracks that you see here. Microfluid X is when you're dealing with any fluid volume that has at least one dimension that is in the microscale. So you're confining the fluid so at least one side of it is a tenth of a millimeter or less. We make these really tiny structures to confine liquid and once you squeeze liquid into these small volumes, it changes its behavior. The fluids have something called laminar flow rather than turbulent flow. So imagine you have two garden hoses and you connect them into a single hose. And one of the hoses you have a blue dye and in one of them you have a red dye. What are you going to see after they join into that single hose? It would turn purple. If you redivided the hoses, you would just get purple water out. Now if you do this in a microfluidic channel, you can make the same kind of setup. So I can make a channel that has a blue dye, make a channel that has red dye, but these channels are very, very small now. If I make them join in the middle channel, there's no wall separating these two fluids. This is what's going to happen. Half of it's going to be blue, half of it's going to be red. They're not going to mix together. Now we have such a few molecules moving through this volume that they're not turbulent anymore. They're all moving in very parallel lines. So think of more like traffic on a two-lane highway. They're just moving in their own lane. This main channel here doesn't have any wall, but the two dyes can remain separate. And if I, you know, re-split the channel, then eventually I'll just get, or I can get just blue water out and red water out. So this is something that, another thing that can occur in microfluidics that is unexpected, you know, based on our everyday experience. So we kind of got an introduction into what microfluidics is. I'm going to shift a little bit to what we can use it for. Some global issues as defined by the United Nations. So one is climate change. Access to fresh drinking water is related to climate change, but also listed as its own separate issue. And also health, which includes access to healthcare as well as the quality of healthcare. This is kind of tangentially related to climate change, but it is a microfluidic device. This is work of one of my colleagues, David Ma, in the College of Engineering. They have created a system where if you have a water droplet that's in blue here and you make it move back and forth between two different materials, it transfers electrical charge between those two materials and that electrical charge can then be used to power a circuit. So this is just using the movement of a water droplet, kind of like a battery or a generator. So this is an example of a sustainable power source, the water droplet moving back and forth. And it's connected to this circuit of LEDs. They're turning on and off because of the power being supplied to it by that water droplet. All of these properties here are a subset of the field of microfluidics, but you can see that it's being used to generate energy. So this is another one of my colleagues, Sang Woo Shin, and he and his colleagues developed a way to filter particles from water without using a membrane or a filter because those things can clog as you start filtering out particles. So this one doesn't require a membrane. Instead what they're doing is they are adding carbon dioxide to the water. That carbon dioxide changes the iron concentration in the water that generates the force that will move particles in the water. The direction of the movement depends on the type of particle, so it can either move towards the source of carbon dioxide and move away from the source of carbon dioxide, but if you have particles floating around in water and you run it through this kind of system, you can make those particles move out of that water. You probably use microfluidics for diagnostics without knowing it. So this is an example of at-home pregnancy test strip, so you put some urine on it that gets wicked up by the paper to some areas that have some antibodies to check for some certain proteins to see if the person's pregnant or not. That same kind of principle is being used in many kinds of microfluidic devices that are being developed to go to the market to test for a lot of other things. This project that I'm going to talk about has the longest term vision, and so the idea is that there's a lot of issues when you need a new organ. So why don't you, when you're healthy, take some cells from your body and make an organ so you have like your own spare parts cabinet for later on. From your body you have systems organs, organs, tissues and cells. So if we take cells from you and organize them correctly, we can go back up in that order and make artificial organs. The problem is how do you position those cells? And that's where microfluidics comes in because we're on the same scale as those cells. We are using a platform to be able to move around individual cells. We call this our micro robot platform. So the idea is that you have some volume of liquid, you can have cells in there, and then we have air bubbles in that liquid, and we can use light to control where those air bubbles move in the liquid. So this video that you're seeing is an air bubble pushing around a smaller object that's about the size of a cell. This image on the top, this is from a microscope. So these are small plastic beads about the size of a white blood cell and we made them spell UH. Just remember that the takeaway message is that you know why these tracks are forming on the sides of your wine glass. All the work here I have to credit to all the very great grad students that I've worked with. The micro robot work, the bubble moving around stuff, a lot of that was done by my former PhD student, Arif. Want to know more about Professor Aaron Ota? Check him out at ee.hawaii.edu.slashfaculty. Want to know more about the College of Engineering at UH Manoa? Check it out at eng.hawaii.edu. Want to know more about the Science Cafe? Check it out at high-sci.org. And now let's check out our ThinkTech schedule of events going forward. ThinkTech broadcasts its talk shows live on the internet from 11 a.m. to 5 p.m. on weekdays. Then we broadcast our earlier shows all night long and on the weekends. And some people listen to them all night long and on the weekends. If you missed a show or if you want to replay or share any of our shows, they're all archived on demand on ThinkTechHawaii.com and YouTube. For our audio stream, go to ThinkTechHawaii.com slash audio. And we post all our shows as podcasts on iTunes. Visit ThinkTechHawaii.com for our weekly calendar and live stream and YouTube links. Oh better yet, sign up on our email list and get our daily email advisories. ThinkTech has a high-tech green screen studio at Pioneer Plaza. If you want to see it or be part of our live audience or if you want to participate in our shows, contact shows at ThinkTechHawaii.com. If you want to pose a question or make a comment during a show, call 808-374-2014 and help us raise public awareness on ThinkTech. Go ahead, give us a thumbs up on YouTube or send us a tweet at ThinkTechHI. We'd like to know how you feel about the issues and events that affect our lives in these islands and in this country. We want to stay in touch with you and we'd like you to stay in touch with us. Let's think together. We'll be right back to wrap up this week's edition of ThinkTech. But first, we want to thank our underwriters. Okay Cynthia, that wraps up this week's edition of ThinkTech. Remember, you can watch ThinkTech on Spectrum OC16 several times every week. Can't get enough of it, just like Cynthia does. For additional times, check out oc16.tv. For lots more ThinkTech videos and for underwriting and sponsorship opportunities on ThinkTech, visit ThinkTechHawaii.com. Be a guest or a host, a producer or an intern and help us reach and have an impact on Hawaii. Thanks so much for being part of our ThinkTech family and for supporting our open discussion of tech, energy, diversification and global awareness in Hawaii. And of course, the ongoing search for innovation, both macro and micro, wherever we can find it. You can watch this show throughout the week and tune in next Sunday evening for our next important ThinkTech episode. I'm Jay Fiedel. And I'm Cynthia Sinclair. Aloha everyone.