i'm thrilled to be here tonight to share with you somethingwe've been working on for over two years, and it's in the areaof additive manufacturing, also known as 3d printing.
what are the limitations of 3d printing, you see this object here. it looks fairly simple,but it's quite complex at the same time. it's a set of concentricgeodesic structures with linkages between each one.
in its context, it is not manufacturableby traditional manufacturing techniques. it has a symmetry suchthat you can't injection mold it. you can't even manufacture itthrough milling. this is a job for a 3d printer, but most 3d printers would take betweenthree and 10 hours to fabricate it, and we're going to take the risk tonightto try to fabricate it onstage during this 10-minute talk. wish us luck. now, 3d printing is actually a misnomer.
it's actually 2d printingover and over again, and it in fact uses the technologiesassociated with 2d printing. think about inkjet printing where youlay down ink on a page to make letters, and then do that over and over againto build up a three-dimensional object. in microelectronics, they use something called lithography to dothe same sort of thing, to make the transistorsand integrated circuits and build up a structure several times. these are all 2d printing technologies.
now, i'm a chemist,a material scientist too, and my co-inventorsare also material scientists, one a chemist, one a physicist, and we began to beinterested in 3d printing. and very often, as you know,new ideas are often simple connections between people with different experiencesin different communities, and that's our story. now, we were inspired by the "terminator 2" scene for t-1000,
and we thought, why couldn't a 3d printeroperate in this fashion, where you have an objectarise out of a puddle in essentially real time with essentially no waste to make a great object? okay, just like the movies. and could we be inspired by hollywood and come up with waysto actually try to get this to work? and that was our challenge.
and our approach would be,if we could do this, then we could fundamentally addressthe three issues holding back 3d printing from being a manufacturing process. one, 3d printing takes forever. there are mushrooms that grow fasterthan 3d printed parts. (laughter) the layer by layer process leads to defectsin mechanical properties, and if we could grow continuously,we could eliminate those defects. and in fact, if we could grow really fast,we could also start using materials
that are self-curing,and we could have amazing properties. so if we could pull this off,imitate hollywood, we could in fact address 3d manufacturing. our approach is to usesome standard knowledge in polymer chemistry to harness light and oxygento grow parts continuously. light and oxygen work in different ways. light can take a resinand convert it to a solid, can convert a liquid to a solid.
oxygen inhibits that process. so light and oxygenare polar opposites from one another from a chemical point of view, and if we can control spatiallythe light and oxygen, we could control this process. and we refer to this as clip.[continuous liquid interface production.] it has three functional components. one, it has a reservoirthat holds the puddle, just like the t-1000.
at the bottom of the reservoiris a special window. i'll come back to that. in addition, it has a stagethat will lower into the puddle and pull the object out of the liquid. the third componentis a digital light projection system underneath the reservoir, illuminating with lightin the ultraviolet region. now, the key is that this windowin the bottom of this reservoir, it's a composite,it's a very special window.
it's not only transparent to lightbut it's permeable to oxygen. it's got characteristicslike a contact lens. so we can see how the process works. you can start to see thatas you lower a stage in there, in a traditional process,with an oxygen-impermeable window, you make a two-dimensional pattern and you end up gluing that onto the windowwith a traditional window, and so in order to introducethe next layer, you have to separate it, introduce new resin, reposition it,
and do this process over and over again. but with our very special window, what we're able to do is,with oxygen coming through the bottom as light hits it, that oxygen inhibits the reaction, and we form a dead zone. this dead zone is on the orderof tens of microns thick, so that's two or three diametersof a red blood cell, right at the window interfacethat remains a liquid,
and we pull this object up, and as we talked about in a science paper, as we change the oxygen content,we can change the dead zone thickness. and so we have a number of key variablesthat we control: oxygen content, the light, the light intensity,the dose to cure, the viscosity, the geometry, and we use very sophisticated softwareto control this process. the result is pretty staggering. it's 25 to 100 times fasterthan traditional 3d printers,
which is game-changing. in addition, as our abilityto deliver liquid to that interface, we can go 1,000 times faster i believe, and that in fact opens up the opportunityfor generating a lot of heat, and as a chemical engineer,i get very excited at heat transfer and the idea that we might one dayhave water-cooled 3d printers, because they're going so fast. in addition, because we're growing things,we eliminate the layers, and the parts are monolithic.
you don't see the surface structure. you have molecularly smooth surfaces. and the mechanical propertiesof most parts made in a 3d printer are notorious for having propertiesthat depend on the orientation with which how you printed it,because of the layer-like structure. but when you grow objects like this, the properties are invariantwith the print direction. these look like injection-molded parts, which is very differentthan traditional 3d manufacturing.
in addition, we're able to throw the entire polymerchemistry textbook at this, and we're able to design chemistriesthat can give rise to the properties you really want in a 3d-printed object. (applause) there it is. that's great. you always take the risk that somethinglike this won't work onstage, right? but we can have materialswith great mechanical properties. for the first time, we can have elastomers
that are high elasticityor high dampening. think about vibration controlor great sneakers, for example. we can make materialsthat have incredible strength, high strength-to-weight ratio,really strong materials, really great elastomers, so throw that in the audience there. so great material properties. and so the opportunity now,if you actually make a part that has the propertiesto be a final part,
and you do it in game-changing speeds, you can actually transform manufacturing. right now, in manufacturing,what happens is, the so-called digital threadin digital manufacturing. we go from a cad drawing, a design,to a prototype to manufacturing. often, the digital thread is brokenright at prototype, because you can't goall the way to manufacturing because most parts don't havethe properties to be a final part. we now can connect the digital thread
all the way from designto prototyping to manufacturing, and that opportunityreally opens up all sorts of things, from better fuel-efficient carsdealing with great lattice properties with high strength-to-weight ratio, new turbine blades,all sorts of wonderful things. think about if you need a stentin an emergency situation, instead of the doctor pulling offa stent out of the shelf that was just standard sizes, having a stent that's designedfor you, for your own anatomy
with your own tributaries, printed in an emergency situationin real time out of the properties such that the stent could go awayafter 18 months: really-game changing. or digital dentistry, and makingthese kinds of structures even while you're in the dentist chair. and look at the structuresthat my students are making at the university of north carolina. these are amazing microscale structures. you know, the world is really goodat nano-fabrication.
moore's law has driven thingsfrom 10 microns and below. we're really good at that, but it's actually very hard to make thingsfrom 10 microns to 1,000 microns, the mesoscale. and subtractive techniquesfrom the silicon industry can't do that very well. they can't etch wafers that well. but this process is so gentle, we can grow these objectsup from the bottom
using additive manufacturing and make amazing thingsin tens of seconds, opening up new sensor technologies, new drug delivery techniques, new lab-on-a-chip applications,really game-changing stuff. so the opportunity of makinga part in real time that has the properties to be a final part really opens up 3d manufacturing, and for us, this is very exciting,because this really is owning
the intersection between hardware,software and molecular science, and i can't wait to see what designersand engineers around the world are going to be able to dowith this great tool. thanks for listening.
