Published: May 27, 2019 By

Wil Srubar is an assistant professor of civil, environmental and architectural engineering here at C.U. Guided by the tenets of industrial ecology, his team's collective vision is to engineer next-generation infrastructure materials by blurring the boundaries between the built environment and the natural world. Materials of current interest include biodegradable polymers, phase-change materials, recycled aggregate concrete, and natural-fiber composites for green building applications.

Read more: "Frankenstein" materials could revolutionize building construction


Srubar talking to a student in his labAnnouncer: And now from the University of Colorado in Boulder, the College of Engineering and Applied Science presents OnCue. Here's your host. 

Josh Rhoten: Welcome to this edition of OnCue, I’m Josh Rhoten a communications specialist with the college. I recently sat down with Will Srubar, an assistant professor in civil, environmental and architectural engineering, to talk about his research into living building materials. His latest award from the Defense Advanced Research Projects Agency or DARPA could fundamentally change the way buildings are made and takes its name from a classic horror novel. 

Rhoten: So go ahead and tell me about your project that you're working on with DARPA right now. 

Will Srubar: The projects funded by DARPA and it's through their biological technologies office and it's through a new program the engineered living materials program, or ELM program, that really tries to push the boundaries of what materials are able to do. Have them no longer be static but rather serve some sort of biological function. So our project is a tall order, we proposed to engineer a hybrid living material which is composed of an inert structural scaffold so you can think of that is as sand. Like we normally use sand in cement and mortar something that's inorganic and that's non-living that kind of provides a little bit of a framework for a biological component to grow on and to thrive. And so we use that inorganic scaffold to support the growth and viability of a living component. And what we end up with is a material that not only has some structural load bearing function but also has a biological function as well. 

Rhoten: So go ahead and tell me where the title of this project comes from. There's an interesting link to it, right? 

Srubar:  Yes. Yeah there is. There is an interesting link. So Prometheus is an ancient god of technology and it was really fire back then and if those of you well versed in mythology will recall that Prometheus was a little bit bitten by the technology that he was trying to wield. Mary Shelley was inspired by this particular story. And so she subtitled her  Frankenstein novel as the modern Prometheus. And what was intriguing to us as a project team was we were also trying to create a Frankenstein like material and we wanted to learn from our predecessors and actually not see the same fate and to be able to really control the material so as to not get the better the best of us. So we often will speak of this project as the Post-Modern Prometheus where we have finally, after three tries, wielded the technology that we're creating. It also is pretty interesting because we're working with the Cyanobacteria that are really green. So it really does look like a Frankenstein material. 

Rhoten: Right, right you described it that way a couple times too. What does Prometheus actually stand for? 

Srubar: Prometheus stands for the programmable resurrection of materials engineered to heal exponentially using switches. 

Rhoten: It's a catchy title really. The connections are really interesting to the work too. Can you tell me about the genetic aspect that you were talking about before? 

Srubar: Yes. So you know nature has over millennia evolved to give us really great materials to work with starting materials and that evolution involves a lot of genetic mutations along the way. So we're kind of here at this point in time where we have bacteria and other plant cells that do some really great things we know over time further genetic mutations will improve these materials and perhaps make them more ideally suited for engineering applications. So the concept of synthetic biology is to speed up evolution and to do some of that genetic mutation in the here and now to get the products the materials more ideally suited for applications and needs for society that we need today. 

Rhoten: Its… nature is an interesting educator or teacher. Would you say that? Is that kind of what your thesis/process is with your work? 

Srubar: Absolutely. The growing field of bio mimicry and bio memetic design does exactly that. They learn from nature and we infuse a lot of that into what we do in the living materials lab where we identify perhaps a… an organism or even a small molecule that nature has created that does extraordinary things. We try to mimic it in the laboratory. And in the case of this project we try to impart the ability of microbes to make those awesome minerals and materials to serve the application needs that we have identified. 

Rhoten: Can you tell me where this kind of sits in the broader C.U. context? I know you're working with other professors here too. 

Srubar: Yeah. So this we're essentially creating a new discipline in my lab which is the living materials laboratory and what that necessitates is a multidisciplinary approach to create exciting new materials at what I call the bleeding edges of material science. So that necessitates, especially for this project, necessitates a lot of collaborators and folks who are well versed in the biological sciences biochemistry, gene engineering. We can talk about our gene editing and metabolic engineering parts of the project, microbiology but also traditional materials science. And since we are designing these materials for a specific application this necessitates a folks who are well versed in structural engineering structural mechanics and also failure mechanisms of materials. 

Rhoten: Can you kind of tell me broadly, you’ve introduced it a little bit already but broadly what a layperson can understand about this project. What are you trying to do? What are you trying to accomplish with this? 

Srubar: Yeah. So if you look around you in buildings materials are pretty static and pretty inert. And for good reason we want to keep our microbiomes in the indoor environments relatively safe for humans. What we're starting to question though is that paradigm of why do materials have to remain so inert and why couldn't they for example self-heal? Why couldn't they impart some benefits to indoor environments like sequester carbon dioxide which CO2 levels people may not know. CO2 levels are twice sometimes three times as high indoors than they are outdoors. And why couldn't these materials for example provide other benefits like serve as bio indicators when they're when there are elevated levels of toxins in the environment. We see wonderful examples in nature of how communities of insects and other species of animals can adapt and respond to external environmental triggers. And we're just trying to impart a little bit of that too to materials for the built environment. 

Rhoten: Can you… this is your first DARPA project? 

Srubar: Yes. 

Rhoten: Can you talk about maybe some hesitations or some interest in your part in working with them for the first time. Is it something where you didn't know that you could work with DARPA? Your work maybe didn't align in your mind somehow? 

Blocks being made in Srubar's labSrubar: Yeah absolutely. When I when I thought of DARPA, as a new investigator I always thought of DARPA as they would fund the genius projects and they would fund the projects that were impossible to accomplish. And when this program came out and they had a call for proposals I was both hesitant but overwhelmingly excited because for the first time I saw a call from DARPA that really resonated with what it is that I did in my research group but also where I wanted my research to go. And it opened up brand new opportunities for for me and my research group. I often tell my students that you miss 100 percent of the shots you never take. So what I did was I assembled a dream collaborator team. We came up with a crazy idea, we thought it could possibly work. Turns out it's working which is which is excellent. And we dazzled DARPA with an idea because we were proposing to do something no one has ever done before. 

Rhoten: Do you still feel kind of an imposter syndrome with DARPA now that you’ve got it or? 

Srubar: I always feel imposter syndrome, being a first generation college student and having a a background that was while it was very supportive, left me to figure things out on my own. So I always feel a little bit of that I think academics, especially newer academics, feel that they're playing in the big leagues but what I have found with this project is an overwhelming momentum forward with what it is that we're finding in our labs. The overwhelming interest and intrigue that the project is bringing and that instills a lot  of confidence in what we're doing. 

Rhoten: Well what's one aspect of it that you're really interested in or one part of the science are you really excited about or talking about with people. 

Srubar: I think the most interesting pieces of this project are that we are first, questioning the prevailing paradigm of cementitious materials and cement technology really hasn't changed in the last hundred years and we're creating a material that could serve a structural purpose as a replacement for traditional cement. But I think the most important or most interesting aspect of these materials are that we are using cyanobacteria, really green goopy Frankenstein looking cyanobacteria that sequesters CO2 and so while we are creating a living material that's structural that's living, we're also doing a little bit of good for the environment. Because there are very few examples of materials that sequester carbon dioxide as they're living and growing. Plants are really the main example that we see and biomass is another one and we're using one of the microbes in this project that is arguably the best at doing so.

Rhoten: I guess I'm also kind of curious to talk about your experiences with your other investigators in that they bring a different skill set from you. Have you learned from them? What kind of processes has that been for you integrating with them? 

Srubar: The first thing we learned in this project is how to communicate because we all work on different scales from the nanoscale to the macro scale, for example learning a different vocabulary was also very challenging. So what they term as a substrate means something different to my collaborators than what it means to me. And so they've really opened my eyes to different… not only different ways of looking at science and engineering but also recognizing perhaps some of the challenges we encounter and spinning that as opportunities because sharing at least at my scale at the larger scale sharing some of the common challenges that we face in material science really has bolstered some of the microbiology and synthetic biology that we're imparting to the to the project and is leading us in wildly cool crazy directions. 

Rhoten: Can you tell me where we're at with the project right now? How many more years are left? What's the work left to do?

Srubar: Sure. What's exciting about this is is  this was a four year project. We were funded for four years. We're about a year and a half in so we have quite a few years left and and what we had promised to deliver in four years we actually accomplished in a year and a half which is obviously exciting and what we're what we're hearing from DARPA is an overwhelming positive response and support to push our system a little bit further. What else can it do? Really understand the bounds of the material and what applications it may it may serve in. 

Rhoten: Well what's your answer when they ask you that? What do you what do you envision from this project going forward? 

A student in the Srubar labSrubar: When we think of applications of this material we frame it in a way where we really have targeted extreme environments for applications particularly military applications which is of course the what the Department of Defense is interested in as well as the Army the Navy. In addition to just DARPA and the crazy idea is they want a real application. So where we're seeing the most promise for this type of material are in applications of extreme environments where we do see these triggers of temperature such; as area desert environments, even cold desert environments where there may be the environments relatively austere but it's cold. And that would help us then use those switches of switching the material on and off to self-heal and so we see the most promise for those types of military installations in those in those environments. I will also say that an attractive aspect of this this project in the material system that we're working on is that the bacteria help grow the bulk material and we know that bacteria grow at an exponential rate. And so instead of manufacturing a brick or some module one by one by one we envision an exponential increase in the ability to manufacture this type of material where you may create one brick split it into two then all of a sudden you have four bricks you split those. And so it's revolutionizing not only what we think of a structural material but how we even are able to fabricate structural materials at an exponential scale. 

Rhoten: And that kind of goes back to what you're talking about how it's a new field and a new area developing, is it challenging not having other people around to kind of see what they're doing? I mean you're kind of pioneering this in a lot of ways is that a challenging aspect?

Srubar: It's a challenging and exciting aspect I would say. We are rooted in our fundamental disciplines, all of my collaborators are, we are viewed in some cases as just like DARPA is viewed as the ones with the crazy ideas. And while we are still some years away from seeing a true application of this material we do feel that in essence we are creating this new discipline and we're inspiring others to push what is the definition of their own disciplinary boundaries. 

Rhoten: Great. Well thank you for talking to me about it. You bet. 

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