 Welcome back everyone. If you have friends outside please ask them to come in because we have a very exciting session coming up here on sustainable manufacturing. I'm Jenny Milne. I'm the Associate Director for the Advanced Research Projects at the Precourt Institute for Energy and what that means is I help to run the research portfolios. I help define the research portfolios and identify topic areas, craft requests for proposals in defined topic areas and see all the great ideas that come in from the faculty. So this session includes a couple of those projects we funded through a programme called the Precourt Pioneering Projects and we did a call on reinventing plastics. So as you know plastics are ubiquitous, they're everywhere. In fact even in us if you read that New York Times article recently they're part of our bodies now too apparently so I'm not quite sure what we'll do with that but we have to deal with the waste. We're not doing a very good job right now so one way is to to take the waste we have out there and process it in ways that are beneficial. Another way is to completely reinvent plastics. So what you're going to hear today are some interesting projects and over and above what we've funded from these fine professors here. These projects are really looking at how can we reinvent plastics in a way that we don't have as much waste to deal with. Both have 3D printing as a big feature in there and I'll let the professors do the speaking on those topics briefly. I'll introduce Dan Congrive and Danielle Mai who are one project together. They're both assistant professors here. Dan is in electrical engineering and Danielle is in chemical engineering and they're going to talk on a circular 3D printing economy enabled by photon up conversion and then after that you'll hear about 20 minutes from them and then after that Joe DeSimone will talk partially on his project that we funded in getting in front of the additive manufacturing revolution and more broadly about some of the real cool stuff that's that he's doing in that space with his group and then we'll have a couple questions maybe from me on the panel and then go to you the audience for questions and so please think about what you might like to know and ask these professors is a big opportunity here to get to know a really exciting and upcoming space. So with that I'd like to introduce Dan. Yep, Dan, thank you. Thank you so much for that kind introduction and thank you to all of you for being here today. This is such a cool event to not only celebrate the teams that we've built the science and the engineering that we've done but also really take a moment to look forward to the next grand challenges to build teams to do really cool science and engineering to begin approaching those and so in that vein today I want to tell you about some of the work that we've been doing in a collaboration that's lasted a couple of years now focused on can we build a 3D printing resin that you can both print and erase so you can take a resin cure it make your shape but instead of throwing it in the land fill find a way to be able to reuse it again and again and again and before we get started I of course want to thank pre-court for the wonderful funding and the support not only in terms of just funding the project but also providing us the connections the guidance to really push it forward and excel. All right so 3D printing of course is an exploding field we now measure the market in tens of billions of dollars and we use hundreds of millions of kilograms of plastic every year and both of those are growing substantially year over year and this is a really exciting time right there's a lot of really cool work being done we're going to hear about some of it in just a moment but also it's a really large challenge because almost all of those materials are single use right so when you 3D print something you're going to have some material that's lost right away typically in support structures or other mechanisms that goes in the trash right away you use your part and at the end of the day that part goes in the trash as well and so we really urgently need a solution to come up with a way to reclaim and recycle these 3D printing resins and keep that material out of landfills and out of oceans right to put this another way in our economy here currently often you take your printer you print that create whatever really cool thing you're trying to do you separate out and bin those supports and you get your final part that you can use for whatever application you want and at the end of the day you trash that and that ends up in the garbage as well and so our proposal is if we can find a way to regenerate this resin in some form now you can take those support structures and separate them out take your final part and recycle that and reuse this material now it's pretty easy to make a PowerPoint slide with a black box that says regenerate resin on it right that's not that hard to do it's a lot harder to actually go into the lab and figure out the materials that we want to achieve this now there's a couple of different ways that this type of printing and erasing have been proposed and we want to do it and what I think is kind of a unique way which is to utilize light so it's very common these days to utilize light to make chemical bonds right to take your polymer and print it together sorry I don't mean to walk in front of you guys I just like to wander to take your bonds and form your bonds and make your resin into a plastic but we actually want to use the same technique to find a way to break it apart and it turns out to do this you really have to rethink things from a fairly fundamental level right we have to think about how do we design that resin to be able to efficiently make and break bonds how can we design the materials that go within it to enable light penetration we'll talk more about that in just a second and how do we engineer the polymers so that in that final printed part you get all the properties that you want but then you can still erase it at the end of the day and so this is what our team is really focused on now one of the challenges to a light based approach like this is light penetration and that may sound like a really small technical detail but this is actually a really large challenge that spans across fields right I think my favorite example of this is tissue right if you're trying to run a reaction say create a drug at a tumor site do some bio-imaging do optogenetics whatever it is it's often very difficult to get that light to where you want it to be because it gets scattered it gets absorbed on the way in and there's no less a challenge when talking about additive manufacturing right if you want to print a point in the middle of a vat of resin it's very difficult to access that point and just that point right you could for example shine a laser in here but you can see two really key challenges that come up right away first you lose your selectivity right you're not able to really hit a single spot you hit everywhere coming in with your laser and everywhere coming out with it right but second that light gets really substantially absorbed and in this picture here we've actually diluted things down quite a bit but if I were to do this picture with a solid piece of plastic you would find that that light is completely absorbed within the first hundred microns or so right so from an eraser type of perspective if you want to get that light deep within your material it's almost a non-starter it's going to be absorbed at the surface only to remedy this challenge my lab has come up has spent some time studying a process called up conversion this is a process that takes two low energy photons and combines their energy to create one higher energy photon in this process we use it for all sorts of fun things photovoltaics night vision anti counterfeiting but applied to the challenge here it can really address both of these challenges first due to its quadratic nature you can get that selectivity back so you only get that blue light focused at the middle point of the beam that red light comes through and doesn't affect the resin at all and second we can tune the penetration depth to be whatever we want and so this technology can really enable these light based resin adjustments okay and that's our low energy red photons coming in we previously demonstrated that this can be really useful for volumetric 3d printing so taking that selective spot coupling it to a photo initiator and using that to basically 3d print an entire volume of of area here we can see a video of that running for example at the focal point of that laser beam there's a little dot of blue light that couples to an initiator which causes the resin to harden and you just scan that you hit every point that you want to cure in three dimensional space you've built a fairly nice 3d printer no resin flowing nice static resin that all sorts of fun things like that purely optically addressable which is fun and we can make reasonably shaped 3d prints out of that but we want to take this one step further right we want to take this technology and really apply this to how we can utilize this to not only print parts like we see here but also how to erase them and so to be able to do that we need three really big pieces that we need to design sort of from the ground up the first is we need to design our resin in a way that it can be efficiently printed and efficiently erased and the parameter space for this is enormous from what connecting groups what connecting moieties you use you see one example here to what type of arms and densities and all sorts of materials you want to use second we need a way to make sure that that light can be delivered where we need it to be across that entire brick of printed material now we just talked about that one so we can at least partially check that box and then finally we need to make sure that we can quantify this across cycles right this is no good if it only works once or twice we needed to work three four five six you know hopefully infinite times that you can make and break these bonds on demand and so to take a look at some of the steps that we've made some of the science we've developed in all three of these aspects handed over to Danielle to tell you about some of the cool things that we've developed and thank you everybody for joining us today so as Dan laid out this problem for the next few minutes I'm just going to share the progress that we've made in terms of making our first generation resin that can be polymerized and depolymerized so the first piece is this resin design right so in a traditional polymer you're usually on creating really really long molecules one step at a time so you have these building blocks that add on to each other and they do so in a way where it's favorable to just make a giant molecule and it's really difficult to break it all up again right and so our idea here is to use light to give us a way that we can undo that polymerization so we're actually going to start with something called a pre-polymer in our resin so the idea is that we have a polymer that has a lot of different end groups hanging off of it you can see those are the little purple circles in polymer world we draw everything is a squiggly line and from here those end groups are our photo active groups and so we can use those to create bonds by using light so if two of those groups come together then they create a bond when they're exposed to this 365 nanometer light and then we also choose a group that can be unbonded right so we can break this bond using an orthogonal wavelength and so here we're using a higher energy wavelength in order to cause those two bonds to fall apart and we don't just do it on these you know ideal pictures we have real chemistry that are going in so we're relying on something called an anthracene chemistry right now this is a molecule that forms a dimer and then it can undimerize but there are a lot a lot a lot of other photo polymer or photo reactions that we can leverage in next-generation resins so this is just where we're starting for our model material one of the challenges with this particular material is that you see everything is driven by UV light which we hadn't been able to access with Dan's up conversion technology quite yet and so a second major thrust of this work has been to think about how do we deliver UV light deep into a material unfortunately the capsules that have been used in some of the earlier 3d printing resins have requirements that don't work well with the chemicals that you need to do UV based up conversion but Dan's lab in collaboration with us have explored a different type of encapsulation method where we can keep our up conversion materials protected from the solution that they're living in right so now we're able to think about doing up conversion in a water-based environment which has otherwise been really difficult to access and the method that we have here allows us to partition all different types of up converting molecules we've tested I think 20 different kinds and 19 of them work so most of the time it works and we've now been able to demonstrate our ability to focus blue light and turn it into UV light deep within a solution so in the middle panel this is kind of the setup of the proof of principle that we're doing you can imagine if you shine UV light onto a cuvette and you try to focus it to a point you get all of that scattering that we showed earlier on the right here we see the actual image of this where we have a fluorescent reporter showing us where we're getting UV because we can't see UV with our own eyes and then in the bottom when we switch over to a blue light that's going to drive our up conversion process we see indeed far into the solution right almost a centimeter deep into this cuvette we can focus a little point and that allows us to do this volumetric printing using ultraviolet wavelengths so that's two pieces of the puzzle the third piece is thinking about how do we measure all of the materials as we're making them and so I'm going to get a little bit more technical here we do a lot of measurements using something called a shear rheometer so rheology is the study of how things flow right polymers switch from a liquid form into a solid form when you're printing them right and so we're trying to measure when things stop flowing we do this by applying a strain to a material and so you can imagine if the material goes with the strain it's more solid like and then if the material stays in place as you apply the strain is dissipating energy so it's more liquid like and so we want to see when that transition is happening so you'll see on these graphs here is that at short times we get dominant liquid like behavior right this is when we just have that polymer resin and then as we turn the light on let it shine onto a bulk film of these materials we get a crossover where we're switching to this solid like behavior right so we're now switching from that resin with all of these polymer molecules just floating around and then they start to link together and they hit a point where you get this nice stable network that looks what you would want a 3d printed material to look like okay so at the right end here this is all just showing printing in one direction right so what happens when you shine light onto these materials of course we're interested in making this all circular and so we can also swap out the light source on this particular reometer and we can look at erasure our initial things didn't work right research is very difficult and that's why we keep pursuing all of these avenues so in our first pass here we saw that when we switched the light source we do get a weakening of our material so we're softening it and we're doing some on cross linking and this is a log scale so that's probably ninety percent softening but that's not enough to unprint it back into the liquid form right so this is you know part of the challenge of plastics right it's really hard to get them back into that monomer or that small molecule form where they can flow again thankfully we have a great team working behind us and so they've tried a bunch of different polymer structures concentrations things like that and we do now have some promising results where we've hit a point where we're able to fully on cross-linking material and as you can see in this particular graph at longer times we're starting to recross link this material with the wavelength that should be doing on cross linking so we're uncovering a lot of really interesting fundamental science along the way as we're reaching this goal of creating a circular 3D printing resin so with that I hope that you've seen that we can create these resins that can be printed and erased hopefully we can get to more circularity as we continue on in this project we started delivering UV light deep into materials and we're tuning that system to be compatible with the 3D printing resins and then we finally can quantify the performance as we're going through all of these processes so we understand you know how to design all of these materials for that next generation of resin okay so with that I want to thank the folks who are behind the work postdocs Tracy Schlammer and Mike Burroughs have been instrumental in getting all of this online and they've trained a bunch of graduate students who are now continuing the project Mike and Eleanor have a poster later today if you want to check that out and then thank you so much to the pre-court institute and all of our other funding sources for letting this happen. Beautiful to see the innovative work from Danielle and Dan. The share with you a story that is a little bit longer in time and maybe a little bit more context. Manufacturing is a 12 trillion dollar marketplace. Polymeric products is 1.1 trillion of that and 30% of that's injection molded and it's not uncommon for these injection molding tools especially for high performance products like electrical connectors to cost a million dollars maybe take you 6 to 12 months to get your hands on them and once you have them you don't want to make any changes because you have to have that return on investment. And so this is a big part of the marketplace and that inhibition of the injection molding process the time the ROI often stifles innovation because you have to let of your products because you have to reap the ROI on that. Because of the molding process these materials are often heavier than they need to be they could be much more dematerialized. The materials have the properties but the process for making them often doesn't. And it triggers intensive and cumbersome supply chains and there's almost no recycling as it was talked about. And when you think about the supply chain I love this quote from Thomas Friedman on any given day 2% of the world's GDP can be found in a UPS truck. And that speaks to the energy associated with the nature of our manufacturing processes. And not only that because of the way we make things we end up making lots of them and storing them. There's an enormous amount of slow-moving inventory that's in climate control buildings and you know the premise that we talk a lot about is what's the potential for a warehouse in the cloud and changing the dynamics of supply chains and free enough capital associated with storage. So what we've been talking about is molding the formative techniques and the subtractive techniques are very competitive think about milling CNC milling and others. And then we've all been talking about additive. And I think the biggest opportunities for additive manufacturing are making things that you can't mold. And lattices are one of those things and this building and lots of bridges are made with struts. But when you have 14,000 struts you can't assemble individual ones you have to have it appear. And that's really the opportunity and maybe to say something very simple that I think is profound we don't buy things you can't make. And you think about it you've got to be able to make things to sell it. And what that really means is we're talking a lot about manufacturing science here as opposed to thinking about prototypes and the like. And so a product is not a prototype. So 3D printing has been challenged by its slow. The layer by layer approach leads to anisotropy and mechanical properties and material choices have been pretty limited. So we came at this over 10 years ago now with a process that allows 3D printing go 10 to 100 times faster than traditional printing. And it involves a breakthrough in material science for a window at the bottom of the printer. This window here that holds a reservoir of liquid is not only optically transparent but it's also permeable to oxygen. Oxygen inhibits the photo chemistry that the light triggers. And so when you lower this platform into this reservoir it'll get very close to the window. And then you'll see a two dimensional pattern of light emerge from underneath it. And what'll happen is that emerging part will bond, adhesively bond to the platform and not bond to the window. There'll be a gap between the part and the window. And that gap allows resin to be pulled into by suction forces underneath the part. And this is a significant improvement in the speed of 3D printing. This video is sped up. But you get the sense that we can make things much more quickly than had the opportunity to do in the past and you can make things that are unmoldable by using a two-dimensional pattern of light. It kind of looks like Terminator 2 from those movies. Terminator 2 movies. Terminator 2 movies. And so this is actually what's happening. This is optical coherence tomography image of showing the part growing. You see the gap underneath the part. As you pull the part up there's a low pressure here in the center that draws resin in underneath of that growing part. And this allows it to go much faster. And we've worked through all the details of this process. I don't want to go through that here. But I think of this as a software controlled chemical reaction to grow parts. And we've developed printers and processes that are completely controllable with software and resins that are tuned so that we can systematically make exactly what we want to design. And we spun out a company called Carbon. We've been at this for a while. We've now moved this into high volume manufacturing. And this is an example of a fairly large factory in Asia making adidas running shoes. In addition to the printing process going much faster as the challenge is light can be a challenge to make a material with a wide range of properties. Some of the best polymers are made by reactive resins. Think about epoxies and polyurethanes and silicones. No one used those in 3D printing before because they would gel prematurely because 3D printing is historically slow. But now that we're printing significantly faster, we had a window to use these. But those resins are typically not UV sensitive. So we basically combine a UV curing system with a reactive system. And we call that dual cure. And that gives you a wide range of mechanical properties that cure to 4D 3D printing resins typically didn't access. And so this now becomes a platform. We can print fast. We have resins that have the properties to be a final part. And I've got a little video that pulls it all together here for you. We salute all those who believe good enough is never good or enough. Those who pursue excellence for themselves and for our planet. At Carbon, we apply our craft using science and technology to push limits and realize products unmatched in performance. Our difference is one you feel and it is light years ahead of anything else out there. You feel it in running shoes that control energy with every stride. Saddles that enhance your performance and comfort mile after mile. Helmets that increase your protection every time you take the field. Clear aligners and dentures that improve oral health and give you more than a few reasons to smile. Crafted by Carbon is a promise. It stands for dedication and focus to crafting what you and our planet truly need. Ongoing creation of amazing answers to our toughest questions. We salute the leaders, dreamers and doers who keep creation in motion who boldly imagine a brighter future and craft it every day. So this has gotten a lot of traction in a wide range of industries from consumer products to automotive to dental, as you saw there. But when we look forward and we think about, you know, where do we need things to go? We heard some of that earlier in recyclable resins and new resins are able to do that. We also think about, how can we print faster? How can we do multi-material printing and how can we do high-resolution printing and open up new applications? And there's a lot of opportunities here for advancing the software and the operating system and even further. And let me focus on high resolution printing right now. This is what my lab here at Stanford has been doing. This is an example of just a collage of some amazing things from the literature that people are demonstrating, important new concepts in physics and optics and biology. But it's hard to really think about whether you could actually scale these things because they're often made with direct right tools and there's a lot of people interested in accessing these products. So we've put together now the same type of physics and chemistry that I just showed you in the large scale. We've now put together a printer that goes to single digit micron resolution. So we've got built a printer with 1.5 micron resolution and the printers I showed you earlier were 75 microns and up. And we did this by controlling the optics and understanding the reaction engineering and the fluid mechanics and developing the software with the appropriate feedback loops. And just to summarize, a lot of work. We always like to print the Eiffel Tower as an example. This is the Eiffel Tower with the commercial carbon printers that I showed earlier. And then you can start looking at Eiffel Towers with a 30 micron resolution. And then you got that little guy right there at 1.5 micron. So now we're starting to make things that, you know, red blood cells, 8 microns. And so this has got pixel size of 1.5 micron. And so where we're going with this work now is in a number of different areas. One area is in thinking about what gets done in a fab today and in a microelectronics industry and thinking about ways of doing back end of the line packaging, cooling chips, facilitating chip to chip communication, compute and storage on the same chip, those sorts of things. We're also really interested in MEMS. MEMS is a fascinating area. Often these are macroscopic devices and the thousands of micron range as opposed to integrated circuits pushing single digit nanometers. And it's hard to make things at this length scale. And everything in the microelectronics industry is a challenge from an auxiliary chemistry point of view. And this paper is now 20 years old and it's wanted to galvanize a lot of my thinking. And it's got a pithy title, the 1.7 kilogram microchip. And the point is it takes 1.7 kilograms of stuff to make an individual computer chip. You think about all the solvents, the etchants and the like. And I think our lab is generally thinking about is can non-fab approaches and advanced 3D printing techniques dramatically reduce a number of steps and access products that are now being made in a fab but try to do it outside of a fab, do it off the road map and come up with entire new ways of making things. And that's what the lab is indeed doing. And part of this, too, is opening up new opportunities in energy storage. And I'm fairly new to Stanford and I often reflect where you're at influences what you work on. And when in Rome, do as the Romans do. And here at Stanford, when at Stanford, work on batteries. And so we're getting pulled in some amazing projects where there's opportunities for inflow batteries and aqueous zinc rechargeable batteries and thinking about the electrodes. We can print polymers that can be pyrolyzed to carbon, elemental carbon. And opens up new opportunities for flow directing electrodes and other things. And so these are the range of projects that the lab is involved with. We're also moving this into other areas, too. And in particular, we do work a lot in the drug delivery space. This is so I'd love for you to just look at this and think on these other areas I just mentioned that we'll be able to make some progress in the coming years. But we're doing a lot in the area of micro needles. In particular, micro needles as a new approach to delivering vaccines into the dermal space of skin. And with high resolution printing, you can start making structures that you could mold. We could 3D print these. But now we're making on multiple geometries. And this can open up entire new approaches for drug delivery and sequester things into these lattice structures. And part of that is delivering liquids into the dermis. Think about the Moderna type of vaccine or maybe the Moderna vaccine that gets sequestered into these little lattices and they get freeze dried. Liophilize and insert it as now a dry product and it can be reconstituted in your own interstitial fluid in the skin. So the group's working on that. But we keep advancing the 3D printing technology. And I showed you the clip process where you have a negative pressure pulling liquid into that gap. When we stare at this, we recognize that this is a mass transport limited process that chemistry will go much faster. We're not at what's called reaction rate limited. We're a mass transfer limited. And so how do we get more resin into the printer into the printing process into that dead zone? And we've come up with a process that we now call iClip or injection clip. And what we're doing now is we're mechanically injecting liquid into that gap as opposed to relying on suction forces. And when we do that, we have resin coming through the platform through a microfluidic channel that's dynamically created in the design of the part. And we're pushing resin into that gap. And by mechanically pushing it, we can deliver a lot of resin to the gap instead of just relying on suction forces. And we can think a lot about the software to design the channels within the part. And it also opens up multi-material printing. And so that's a holy grail in a lot of the light-based processing. And so we've now demonstrated that this printer can now go another order of magnitude and speed 10 times faster. It can work with resins that are much higher viscosity and do multi-material printing. And let me just walk you through some of the details. This is the diagram of the flow field with resin in a traditional clip process coming from the periphery and then the opportunity for resin now coming through the center of a part with this particular geometry. And it's a fundamentally different process. And it goes 10 times faster. But one of the most interesting things, and Dan showed a lot of the examples of often you see parts with a lot of supports on them. And the reason is the part can fall off the platform when you're printing it. You have to hold the part onto the platform. And the reason is when you have a liquid layer between the solid part and the window, there's something called a Stefan adhesion force. And so this is we put a load cell on the platform. You can measure the load. You raise a platform up 100 microns. You wait for the liquid to flow in and there's a stress relaxation as the liquid flows in, raise a platform, lower it, or the liquid flows in each time. And that part can fall off the platform if there's too much force on the part. It's kind of like if you have a drop of liquid between two sheets of glass. It's hard to pull it apart. Well, when you inject liquid through the part, through the platform, you can eliminate those forces. In fact, you can put so much liquid coming in, it can be like a rocket ship. You could blow it off the platform or off the window. So it's actually different. And what that means is you can now do 3D printing without supports. So this is a Stanford bunny that people talk a lot about here at Stanford. Lots of supports on it. And now we're able to print that by putting these channels in an innervated way through the part. We can eliminate the need for supports and that can reduce the waste in 3D printing. Another thing that we can do and it's sort of a holy grail 3D printing, nobody 3D prints microfluidics because of over curing. The light as was talked about goes further than you want. It's hard to combine light in a Z-axis in one micron layer thicknesses. But with the liquid coming through the channels, it's oxygenated just like the liquid in the reservoir. And that allows us to keep these channels open. They're making negative spaces in the Z-axis. So now we have light control in the XY plane with really small pixels. And then we use fluid mechanics to control the over curing in the Z-axis. And now we have all three Cartesian coordinates. This opens up high resolution 3D printing at this length scale. And so we're making all sorts of interesting devices, all sorts of reactor designs, pumps, all on this microfluidic scale, combining them with micro needles, doing all sorts of new kinds of medical devices. So let me end there. People have been talking about industry 4.0 for a long time. Automation, AI, sensors, inventory control. I think what's held back industry 4.0 significantly is having a digital fabrication technique that actually can scale with manufacturing. And I believe that those techniques are emerging in front of us now. We saw some really cutting edge stuff earlier. This is a little bit more mundane here, but it's getting traction in the field. And it's allowing people to make things digitally instead of the old way. And I think that unlocks the true power of industry 4.0. And with that, thank you for your attention. And we'd be happy to answer any questions. Awesome. Very exciting stuff going on there right from the lab scale into the real world. I mean, it's across the board. So I want to see hands in the air for questions. But I'll start with the first couple of questions if I may. So I want to start from the more deeper scientific side. And so Dan and Danielle, so you're dealing with different polymers than you normally would. So can you say a little bit about these polymers and what other applications they might have? How can your approaches that you're doing here be applied to other things? Because I think it's really cool concepts. Yeah, absolutely. So we started off thinking about how do we make this thing that you can print and erase just for recyclability. But I think there are a ton of opportunities in using that erasure mechanism for other applications. So I work a lot on biopolymers where we're interested in making high resolution structures. So can you use erasure to make, say, a vasculature of something that you've already 3D printed? Can you use that to backfill with a different type of material? How can you make these resins circular in other ways in addition to the light-based circularity? So in our lab, we're starting to explore some protein-based resins, things like that, that would also be biocompatible and degradable at a different time and length scale than what you would have from the initial photocross-linked material. So those are just a few of the applications that are in my mind. I think there are fun opportunities as well as playing with things like the resolution of materials, where you're limited by the light that you can shine on a particular sample. But you could imagine if you can play very careful tricks with these two processes, maybe even occurring at the same time, you can manipulate that spatial dynamic in a way that might allow you to achieve higher resolution than either individual process by themselves. So we're exploring those dynamics as well. I think those will be really fun over the coming years to really tease out and look for opportunities there. Cool. And Jo, if I might. So you presented a whole bunch of different plastics and processes and things. And so what were you most surprised about or excited about in the lab at that fundamental science level or the discovery that you made that most excites you? How hard manufacturing is? It's hard. And an immense amount of respect. I think when we got into this, we were maybe not as understanding of all the different unit operations that it wanted to do to make things. I mean, we thought the sexy stuff of printing and resins was good enough and people could figure out how to clean a part after you make it or how to set up a supply chain. And global supply chains look, we had a factory up and running in Redwood City, just north of here. And we tried to set it up in Germany and it didn't work. And this was going from four printers to a pod of 20 printers. And now we're dispensing resins from 1,000 liter totes and our contract manufacturer couldn't get it to work. You know, I remember going to our board and saying, look, our key customer is not working and I'm not asking if we can spend more money. I'm telling you, we're going to have to spend more money. And and we're now extended over an ocean and a continent in an ocean and come to find out that dispensing process was off by a percentage 1 percent. And they would never have found that out. And it was only our team as chemists, engineers, software people. And so it's all those nitty gritty details. How to clean a part. You know, we print a part. It's got excess resin on it. Can't wash a part at scale with IPA. And we were doing that in the beginning. There's a lot of mixed waste. And so we pioneered, as silly as it sounds, a salad spinner basically for parts that get printed, get spun, excess resin gets spun off, collected, and goes back into the printer. So it's very atom efficient. But that also tells you that the design of the part is not only the design for performance as a running shoe or dental product, but it's also designed to be spun cleaned and its position on the platform was done. And this is a digital world. You've got control of every aspect of it. So you can optimize all the unit operations in manufacturing in ways that traditionally you don't think about. But an integrated approach was necessary. Interesting. Yeah. Yeah, it's a real world application. Those little things that we don't think about in every part of the process that could be showstoppers sometimes. There's no learning curve. There's a doing curve. Interesting. So are we ready with any questions in the audience? Yes, Amy. Hi, Amy Herhold from ExxonMobil. A lot of the discussion is on the recyclability and so that you reduce the material use, which is really important. Curious about the energy intensity for 3D printing, especially with optical methods, is that a, I'm assuming the light energy and all the other processing is pretty small amount, you know, kind of not very energy intensive, but just kind of curious how that compares because that's also a key piece when you think about sustainability and not just the material recycling. Yeah, absolutely. I think that that type of energy inputs a really important question and you'll see huge ranges depending on the type of process that you're using, right? I just I went to Lawrence Livermore a little while ago and saw their metal printing and they're using giant 600-watt lasers, right? It's really cool. I think some of the advantages of some of the techniques we've been looking at is that we can achieve lower power resolution. So for example, that video that I showed was printed with four milliwatts of laser power, so basically less than a single laser pointer to do that 3D printing. But if you wanted to speed that up, right, that video was about a two hour print or so. And so now we're looking at opportunities to do a whole bunch of spots at once, which does mean more power. And so then you're probably looking at hundreds of milliwatts of laser power to do that type of process, which I think is a pretty normal range for these types of processing for sure. And I think building on that, the dual cure resin concept I mentioned where light is simply used to set the shape. These are low power applications. And then how do you get to a great material properties and this is part of our pre-court program is looking at other ways of setting the shape where only maybe 10%, 15% of the resin that's converted to a polymer on the printing process and the rest of it's sitting there late. And then how do you trigger that second stage reaction? Well, there's work being done where there's something called a frontal ring opening metathesis polymerization where it's actually one of the few you can just touch it with a heat source and then the exotherm of the polymerization drives a polymerization front through the whole part. And so it's really taken advantage of the exotherm of polymerization to drive the conversion. So you start combining all these and all of a sudden you're into a very different, much lower energy situation. You know, the traditional way of making polymers is you run a reactor, you turn it to polymer and then you pelletize it. And then you're shipping the pellets all over the world and then you heat it back up into the melt, into injection molding, which is very energy intensive. Here we're crafting the polymer, or crafting the part while we make the polymer. They're coupled. It's fundamentally different than the way things are typically practiced. More questions? All right, I'll ask another. I'll give you some more time. Ah, ee. Boss, the answer. Boss has got a question. I can't ignore that one. I've been waiting. Well, first of all to share, one day I worked on campus. I noticed so many people look at me. I said, that's a rare treatment. And then one person come up to me and say, I like your shoes. I look at my shoes. I have Adidas right there with 3D printing, I think by carpet. There's only one kind. That's only one kind, very comfortable. So this is not for advertisement. This is a real user experience right there. But I cannot claim the credit yet from political institute. But I'm glad to see this is into the real product. So one question I have. Three of you presenting very exciting idea. I think looking forward what we should do. I also want to pick your brain about the damage we already made, the plastics everywhere. How do we deal with the plastic floating around? You must have thought a lot about this. It'll be good to see your thoughts. Well, since I'm the oldest one up here and probably helped contribute to that problem longer than the others have. It is a problem. And look, I actually think, and this is what's beautiful about Stanford. You could snap the chalk line today and say no more research and make a significant difference on this problem by changes in policy. There's some solutions out there. But this requires business models and policies to play a much larger role than currently has done. And in the fact that companies have no responsibility, I think in many ways that they can make products, they sell it. And now you see the leadership of a number of companies. I know Exxon's building an amazing plant to turn polyolefins back to oil precursors. I mean, it's cracking. They're great at that and they're building a large plant. And so it's that kind of leadership that has changed in a recent time to allow these things to happen. And I'm most excited about that. I think the failure of governments to do things and companies are now playing the role. Adidas, to your point, has a program called the Loop Shoe, where the outsole, the midsole, the upper and laces are all polyurethane. They believe in a polyurethane economy because polyurethane chemistry is reversible. And so I think it's company, and they have a mechanism for making shoes and collecting them at the storefront and get into new business models. And so I'm a big believer in industry leading these kinds of things, because there hasn't, and I think there's technologies out there that can make these things happen already. Yeah, I mean, I think building on that and we've all contributed to plastic. So it's not just a joke. I think that there's a lot of room, not just to recycle back to the monomer, which is what a lot of corporations seem to want right now, but to recycle back to some sort of polymer precursor that can be blended. I think one of the hardest things right now is multi-material plastics. You get these layered materials. Each layer has a different property, whether it's oxygen barrier, water barrier, things like that. And once you blend it all up, those properties don't add together. They actually get a lot worse in that blend. And so thinking about what are technologies that we can generate to address that issue, right? How do we turn these multi-layer materials into new layers that are still actually quite good, right? I think that's an area that we may wanna be focusing in. And let me just build upon that in another pivot to her point. I think there's over 200 different polymers used to make a car today at a 40 classes. And what's cool about light-based manufacturing is you can now bring geometry to the game, lattices, where now one polymer with an intrinsic set of mechanical properties can give you a family of properties by geometry. And now I think that gives you an opportunity to dramatically reduce the number of different polymers that allow a recycling to happen much more appropriately than it's hard to, Daniel's point, recycle so many different ones. But if you gotta use geometry, that one can allow you. And I think you could build a car out of six or eight different polymers instead of what's currently done by using geometry with different materials. And I think a key final point to all of this discussion is the cost of all of these processes, right? I think Bill Gates talks a lot about the green premium, right? If you don't come up, if your solution isn't cost effective, it's not going to be implemented, right? And so working really engaging with companies to look at can we do this fundamental technique? Like that's our job to figure out how to do this. But then how do we build that at a scalable level that it can be adapted, that it can be utilized in a way that's cost effective with current approaches is something that really we have to consider and something we've been increasingly thinking about building into the DNA of the design, right? Not starting with let's get it to work and then figure out how to make it cost effective and scalable, but actually approaching it from the start of saying how can we really take this idea and build that scalability into its DNA into the idea itself? Yeah, it's really cool, great discussion. Thank you so much for those interesting insights. I had a good question about the circularity of these polymers. I was wondering if the fact that they're circular does that impact the reliability of the product that you build using them? Yeah, I think that's really something that we want to carefully investigate, right? The goal for us is to make them as close to that final product as possible, right? And so the way that we've found to be most effective to do that is to utilize that polymer backbone, which provides a lot of support and then have these bondings that occur to give you that reversibility, right? So the discussion of sort of that pre-polymer allows us to get closer there. I think inevitably there will be some sacrifices in material performance, right? Just by the design of it. I don't think we can jump all the way back to just like a pure polymer. And so the vision would be that we're not targeting every application forever, right? We're not gonna probably want to print something that goes on the space shuttle, right? But if we're gonna print something that you're going to use as a fit test, for example, for prototyping that you print apart, you're like, oh, great, it fits or it doesn't fit. You can immediately recycle that and you'll be in good shape. So we're hoping to get to that level of sort of good enough, right? Where you can get a lot of the properties you really need to push forward. Yeah. Thank you. Great, thank you, great discussion. So I have a couple of more questions, but we can, oh, great, Jimmy. Yeah, fantastic. I was wondering, has there been any sort of technical economic analysis where compared to where you have 3D printing, maybe at a local site, which is very distant, as opposed to having something which is manufactured centrally, you know, halfway around the world and then they're gonna ship and all that. Has there been any sort of comparisons to the 3D prototype kind of printing and as manufacturing versus traditional ways of doing it and then shipping and inventory and all those other things? There have been a number of studies and, you know, I think COVID really reinforced for everybody the challenges of global supply chains. If you remember in the beginning, there was a shortage of nasopharyngeal test swaps. I didn't know what that was in the beginning. And the largest factory for making those was in Lombardi, Italy. And that was hit the hardest in the beginning of COVID. And the US Air Force was shipping, you know, the last pallets of swabs over to the US and the 3D printing community has a lot of printers in the dental industry and dental visits went to zero. And so there's a really interesting a business school case study where those dental printers got repositioned to make nasopharyngeal test swaps. In fact, we ran a clinical trial here at Stanford for her patients to show equivalency of a medical device. So there was an example of rescuing supply chains and the adaptability that a digital manufacturing process has that if you did molding, you can't adapt. And so this is where there's a lot of activity now thinking through what that means of local for local production, flexible factories, the ability to, there's nothing more important than keeping your factory running full stop, but having a blend of products that allows you to do that. Where it's hard, a lot of products are seasonal. Think about ski boots and sports equipment and how do you even that out? And so yeah, there's lots of opportunities for thinking through those and a huge advantage is of doing that. And let alone inventory, as I mentioned, there's billions of dollars in slow-moving inventory just waiting to be used. Just freeing up that capital has got a huge, imagine if you could free up that capital. If you're a CFO today and you're trying to make a big difference, freeing up capital is like the first thing you look to do. Great, so I'll ask one final question and I believe we've touched on this a little bit is what would you say, so for these 3D printing fields as a whole and maybe from each of your perspectives, it could be different. What's holding it back? Like what would you say is the top three things that you would like to see change in the world to see this grow to the degree that you think it could? Top three makes it hard. We've got to enumerate it. Pick. Just one. Pick that you're top, however many. I'll do that all the time, let's see. Okay, try three. You did three live, right? So I think, and we've touched on these already and I don't want to steal Joe's thunder at all, but I think the materials is really important, right? Getting the entire sort of flow of the process, oh man, I'm really stealing you, I'm realizing in real time, but getting that entire flow from design all the way to finished product in your hand, getting all of those details tightened down, not just the printing, and then I think the scalability and the sustainability of the technology, right? Especially with addressing some of these waste concerns. Those are the three that jumped in my mind immediately. Yeah, so I can't, I mean, there are so many challenges. I think the biggest one is really the flexibility of the materials and the accessibility of the materials, right? How do you create a resin that you can ship anywhere? It's not gonna cure from the heat during the shipping. It's gonna make it to its destination. It's going, and it will have the properties that you want. All right, so I think tuning all of those different parameters in a really robust deployable way is still really challenging. Yeah. Give you one example of a product. So think about Invisalign product. You know, that's a dental aligner. It starts with 3D printing a replica of teeth, and then you thermoform a clear sheet of plastic on top of that, cut it along the gum line, pop off the aligner, that's the product. That 3D printed replica of teeth is a thermoset. It's used for about 15 minutes to make the aligner. It's gonna be around for 10,000 years. That's dumb. And I think some of the resins you see here could convert that solid back to a liquid. It's probably gonna cost more. It's gonna cost more. It's easy not to do that. And so what is the driver for those kinds of things? Again, I think there's technologies out there, and this is the importance of Stanford and Precourt. You know, it's these policy decisions, these business models that have got to be coupled with technology to come up with these kinds of solutions. And so I'd point to that, since they said a lot of my answers earlier, I would throw the gauntlet over to the metal side. They've got to come up with some techniques like we have to go faster. Metal based 3D printing is something that I think is a really important area, but it still hasn't had a big breakthrough yet. And I think that's one that I would point to. Awesome, great. So we are right up at our time, I think. Or we have maybe, yeah, we have two minutes if anyone has a question. Otherwise, I think we should really thank our panel a great deal for this wonderful discussion. Thank you all for hanging out and being engaged. I'm glad I didn't miss this. I hope you feel the same. So thank you, Dan, Danielle, and Joe for being here and for the enlightening talks and discussion. Thank you all. Thank you.