Podcast: Building Bones with Bacteria-Infused Ink

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29 Mar, 2023

The method could be used to restore damaged artworks © Eva Baur

The method could be used to restore damaged artworks © Eva Baur

In this episode we talk about how researchers at EPFL have developed a new method of 3D printing bone-like composites using bacteria-infused ink. The process involves the use of hydrogel as a printing medium that provides a scaffold for bacterial growth, which produces calcium carbonate crystals that mimic the properties of bone.

In this episode we talk about how researchers at EPFL have developed a new method of 3D printing bone-like composites using bacteria-infused ink. The process involves the use of hydrogel as a printing medium that provides a scaffold for bacterial growth, which produces calcium carbonate crystals that mimic the properties of bone. The resulting material is biocompatible, biodegradable, and has potential for use in bone tissue engineering applications. 

This podcast is sponsored by Mouser Electronics.         


(3:00) - 3D printing with bacteria-loaded ink produces bone-like composites

This episode was brought to you by Mouser, our favorite place to get electronics parts for any project, whether it be a hobby at home or a prototype for work. Click HERE to learn about how additive manufacturing is being leveraged in the medical industry from bone replacement to dental guides!

What’s going on, folks?

Welcome back to the NextByte Podcast, and if you have not left us a review on Spotify yet, we’re, we have a bone to pick with you, and that’s a great segue to this episode, because we’re going to be talking about 3D printing bones, if you care about medicine, if you care about biomimicry, if you think additive manufacturing is cool, then buckle up because this one’s for you. Let’s get into it. 

I’m Daniel and I’m Farbod, and this is the NextByte Podcast. 

Every week we explore interesting and impactful tech and engineering content from Wevolver.com and deliver it to you in bite-sized episodes that are easy to understand regardless of your background. 


Farbod: All right folks, as you heard, we’re talking about 3D printing in this episode and I guess to be more exact, we’re talk about 3D printing as it relates to the medical world.

Now, before we get started, I want to talk about today’s sponsor, that’s Mouser Electronics. So, folks, you’ve heard us talk about Mouser before, Mouser is one of the worlds biggest electronics distributors and the cool thing about that is that they have a lot of connections to a lot of different industries. 

Daniel: And for that reason, we love Mouser. 

Farbod: Exactly, they’re like the plug for all things cool and tech.

Daniel: The components and the information you need to learn about how these components work and what the trends are, and what the new technology is, right? 

Farbod: Yeah, we always talk about the sauce, right? So, imagine having the sauce with the recipe and the cooks and the chefs and everyone together in one spot, and that's basically Mouser. So, they have these Technical Resources where they talk about cool things happening and Industry, Academia, and theme with today's episode, they have this article that discusses 3D printing is application in the medical route. Specifically, they talked about how it's being leveraged, you know, due to the fact that you can develop different geometries and take scans, how you can develop biocompatible structures for bones or like Dental guides.

Farbod: And I mean, Dan, you worked in Formlabs, I think during the time that they were creating those nasal swabs for covid, right? 

Daniel: Yeah. 

Farbod: So, applications like that, this is the primer, this is the TLDR of you going down the rabbit hole to learn about how 3D printing is being leverage for all sorts of medical applications. I think it’s super cool, I enjoyed reading it. As always, we’re going to be linking it to our show notes. So, if you’re interested after this episode and again you want to go down that rabbit hole, check it out.

Daniel: Yeah. And I’ll say like, I think what we’re talking about today, right? Is how to 3D print bones, right? This team from EPFL Materials Lab? 

Daniel: I think this could ultimately be like the fifth or sixth category of medical 3D printing that’s mentioned in this similar type of article in the future. So, it’s kind of cool, it’s like the medical 3D printing 101 and the background and then you get to understand now with us the future of 3D printing in the medical routes specially as it relates to 3D printing bones.

Farbod: Yep. And on that note let's transition to the article. 

Farbod: So, you talked about it, this is coming out of EPFL Soft Materials Lab and the premise is really 3D printing bones. All right, we got provide some context here. I'm going to try to do my best but if I miss anything fill the gap. 

Farbod: So, 3D printing is promising for all the great reasons that we've always talked about. It's a method that is like fairly straightforward. You don't need to develop some crazy complex tool to pour liquid into like injection molding. You don't need some super expensive machine that does CNC Machining. So, for most people it's affordable and pretty effective to use not scale but for like, custom parts, especially. 

Farbod: There's the ease of access the complex geometries that you can accomplish that again are super challenging to do with other different manufacturing approaches. But when it comes to Mineral 3D printing, think like structures that have the properties of Ceramics, right? 

Farbod: We have metals, we've been able to do that with SLS printing. We have polymers that we've been able to do with like FDM, that's where you melt the plastic and then you design your shape, that's most 3D printers do. When there's also SLA where you have this like vat of resin that you shine light on and get the geometry, you want. But Ceramics, we haven't really cracked before. 

Farbod: Now, there's material benefits that are specific to ceramics. So, we'd be great if we could get them with the same advantages that are accompanied by 3D printing. But previous approaches have struggled with this on, for multiple reasons. One of the more important ones being that if you want to like print it through the FDM approach. Remember, that's the one where you melt the plastic and you get it out. You want this material to be printable, which means it's you should be able to like melt it or have it be gooey but also like a solid like you don't want it to fall apart as a prints, right? 

Farbod: And that's challenging. Like other folks have not been able to really do this well except some stabs at this where they put in different additives so that they can do the printing with the downside that once it's done and you want to cure it the material shrinks and it cracks and again, you're starting to compromise on the benefits that are accompanied with additive manufacturing. So, if there was a way to reliably do this manufacturing approach with these minerals and ceramics and all that jazz would have a lot of impact in the fields that could leverage from it. And this is the interesting part of the article to me. 

Daniel: Ceramics in general, right? Were you're referring to like a certain material class. The natural version of ceramic composites are bones, right? So, when you're talking about putting minerals, you're talking about printing Ceramics, this also talks about all the challenges people have faced today to be able to 3D print bone. Like, let's say, is a bone graft or like to try and replace a chip in someone's bone or to try and replace a bone in someone's body. All of those specific manufacturing methods, you're talking about these challenges with 3D printing that applies to the medical realm as well, as well as a ton of other places where you want to use mineralized ceramics like bones, right? 

Farbod: Right. And the thing that got me is that as I'm reading the article, the one thing that came to my mind was bones, right? That's the biggest value at that, I can see. But then they talked about different examples that range from like art restoration, like for Ceramics to environmental restoration like the coral reefs.

Farbod: And that's not at all what I was thinking of, but that just goes to show like what a gap there is in the coverage of materials that are supported by me additive manufacturing right now and what kind of impact and benefits that this thing can have if we can crack the code, right? 

Farbod: So, I mean we've teased it enough, we've set up the problem, we've talked about issues, let's get into the freaking sauce because that's where all the flavor is the secret sauce. 

Daniel: Well, let's say like, we talked about it. The challenges so far today, right? Every time you're trying to 3D print, something you either to date have required it to be a liquid to flow through a nozzle. Or it's got to be a solid powder and if you try to melt that in the right way, it's going to be way too porous for you to use in a bone structure. So, those are our constraints, we either got to have a liquid, or we've got to have this powdery poor solid. Everyone that try this today has not been able to figure it out correctly because they're trying to like have a liquid matrix that holds a bunch of particles that are similar to bone, the ceramic and then you know, you print this together and hopefully it fuses into something that's strong enough that hasn't worked. 

Daniel: The steam from EPFL and it's interesting there from the soft materials lab so you can tell which of the two options they're going with, right? They're going with the liquid option, not the tons of powders option.

Farbod: The name, gave it away, you're right. 

Daniel: Yeah, you know I would say it's a great title for that lab told us exactly what they're doing. They're printing a soft material here. But the thing is they call it BactoInk.

Daniel: And the “Bacto” part is really important because it's a 3D printable link that has really high dimensional stability, right? So, when you print everything, you know, exactly what shape you're going to get and it's there with 99. some number of nines accuracy. But in that ink doped instead of, you know, including a bunch of ceramic particles that are trying to pretend to be bone. It's actually full of calcium carbonate producing bacteria so it's this Liquid Ink full of bacteria and then they're able to cause these bacteria to calcify the whole 3D printed shape and they can basically 3D printed virtually any shape with super high dimensional stability, which gradually mineralize has over the course of the next two to three days to over 90 percent, mineral content by the time they're done. And I think it's incredible, right? 

Daniel: So instead of trying to print the bones themselves, their printing, a precursor material for that, which is a scaffold for these bacteria to live in and they're printing the ingredients for bones and then growing a bone based on that shape which I think is super cool.

Farbod: It's ingenious and it reminds me of like one of our first, I want to say five episodes where we talked about the research coming out of Carnegie Mellon to bio-print the heart and they were having similar problems. Or like look, there's tissue that we want to print, it can't support itself if we do normal printing. So, what we're going to do is we're going to print it in this hydrogel, and a hydrogel is going to be the supporting structure and the bio-ink material that we have is the precursor for the tissue, we're going to post process it by heat treating and at the end, we're going to get the material property that we want in the geometry that we want.

Farbod: So, what you got here is these folks being like, well we're just going to print the precursor material. It's good enough to support itself. And then by the way, these bacteria, it's called “Sporosarcina pasteurii”, it sounds like a cold cut. Like, I could go to a deli and order it, but it like you said it turns to calcium carbonates when exposed to urea. And I was kind of concerned when they said urea turns out that's not actually urine, it's a component of urine. 

Daniel: It’s what is named after.

Farbod: Yeah, it's what it's named after. If you didn't know audience, it's not actually urine, it's a compound that you can use to cure stuff in the lab. And it calcifies and you can use it, it is a biocompatible product. But one thing that I think is worth noting, this thing is made from bacteria before they do anything with it. They don't get in a vat of ethanol to kill any bacteria that might be left.

Daniel: So, you're left with this 90% of the original mass is now converted to this pure calcium. You know again mineralized bone-like structure. There's no bacteria in there. The structure is actually really similar to the biological structure of Bones. That's why they immediately say. And it's like kind of the I don't want to say cliche but it's the low-hanging fruit application for this, which is, let's go put this in someone's body, right? Has a prosthetic for a bone or something like that, right? It's got the right material, it's got the right structure, it's safe to the body. It's super, super interesting, but you kind of alluded to it earlier. They're a bunch of other, like, pretty interesting applications for this where I didn't know, we were struggling to find a way to 3D print minerals for this, but when I think about it, it seems like the right application. 

Daniel: So, you mentioned one of them which I think is really cool. The restoration of art. So, a lot of Arts are made from ceramics, statues and vases. They need to be able to 3D print something to very specific geometry that won't shrink, right? It's got a lot of dimensional stability and they also need that's mineralized to be strong and also mineralize of a similar material so it blends in with the rest. Another thing we could we could restore chips and thousand-year-old statues and sculptures and vases just by 3D printing these unique parts and putting them in and then calcifying those 3D printed parts in place which I think is super cool and definitely an application I wouldn't have thought of off the top my head. 

Farbod: Yeah, and then you know I'm already mentioned it but there's the coral reef stuff that this could be a great application for and obviously there's the bones. Like I think the golden material for any sort of bone replacement right now is Titanium because it's just so incredibly durable and light and strong and biocompatible, but it's so expensive. 

Farbod: And now if you have a way to literally 3D print, the part of your body, that's degrading. I guess it'd be like getting an oil change, right? Like oh you need a new knee cap like boom. Umm, here we go. Yeah, good as new. 

Daniel: It's kind of crazy to think of and I hate to like, lupus back around this. But artificial coral is a like, that seems like a huge development for us. The reef ecosystems are a lot more important than people have ever thought of, right? 

Daniel: The coral reef are like the major habitat for a lot of our ecosystem for fisheries and stuff that we depend on from the ocean and the fact that our pollution in the ocean and are, you know, basically our human footprint has caused fourteen percent of the total Coral Reef in the world, to degrade and died in the last decade. That's something that should we should take pause for because that's basically saying, you know, we're taking away the building block for this, the oceans ecosystem.

Daniel: And by the way, we've consumed 14% of it in the last decade, you know, that at this rate, it’s not looking good. 

Daniel: So, it seems super cool to be able to 3D print are placement for a coral, and like I would be really excited to see if they can demonstrate restoring a significant part of a coral ecosystem, a reef ecosystem based on their 3D printed artificial Coral, from a biological perspective. That'd be interesting to me to see like, if the rest of the reef ecosystems willing to interact with this because, again, it's got out of the rate structure. It's got out of the right dimensions and stuff like that. 

Daniel: At the same time, I'm also from like a preservation of the human race perspective. I'm really excited to see if this is a way for us to kind of erase back some of the impact that we've made on our Earth largely unknowingly. But now that we know about it, we have this charge of like trying to fix it as fast as we can.

Farbod: Yeah. And one thing that's I think worth noting with additive manufacturing. Again, there's a bunch of different materials sometimes you know you're using plastics that are not recyclable or not great for the world but you need it. Like you just need those properties and there's no pork around. An added benefit of what these folks are doing here is that the precursor materials actually, very environmentally friendly. 

Farbod: And the end product is calcium carbonate, which is again biocompatible at, in the right conditions biodegradable, I'm pretty sure so, you're not going to damage the environment.

Daniel: Exactly, right. And like a lot of other ceramic manufacturing processes. Like, even if you think about, like, making something with clay, and putting it in the oven, right? Putting it in that Kiln, requires a ton of extreme temperatures, right? That's an environmental impact as well in that conversion process. Yep, that's something that doesn't exist here, right? They can do it at room temperature, in a vat of material that's naturally occurring and these bacteria is naturally occurring and at the end of the day, they dip it in some ethanol to make sure that it's safe and they can put it in human body, they can put it in the ocean, they can put it on art. They don't even have to just 3D print this ink, right? They can cast this ink into a mold so they can exactly fit the geometry of the art that they're trying to repair. It seems really interesting to me and my favorite part about all this, the twist about all, this is the biomimicry that this is kind of inspired from. 

Daniel: To me, this feels a very similar to the way that bones actually grow, right? So, bones grow by these cells called chondrocytes there on the growth plate, at the end of your bone. They basically provide a scaffold on the end of your bones when your bones are growing and extending, they provide a scaffold for more bone to calcify, on top of it, which is basically you know if you zoom out and try to believe with me here, that's basically what they're doing here. The 3D printing a scaffold for it. They've got the right bacteria in there. They've got the right environment to be able to force calcification to happen. It is very similar to the way the bones grow inside the human body, where there's a couple chondrocyte cells. They're creating a scaffold for more calcium to be built on to the end of the bone. 

Daniel: To me, it feels like there have not only borrowed nature's calcification recipe, let's say to create these awesome composites that are light and porous but also the very strong and rigid. They've also been able to do it in a way that is compatible with our state-of-the-art manufacturing methods, like 3D printing to where you can fine-tune the geometry. You can do it exactly the way you want and you can do it in a way that is bio-safe, eco-friendly, etc. 

Daniel: I don't know if you can tell I'm a huge fan of this work from the EPFL Soft Materials Lab, but I think this will have immediate impacts in our world in the years and decades to come. 

Farbod: Now I'm totally with you, man, and you pointed to it earlier, but I didn't try, like, I should have this thing is called “BactoInk”. What a great name, what an absolutely great name descriptive to the point, rolls off the tongue nicely, I love it. 

Daniel: I give it an 8.9. 

Farbod: Yeah. No, that's it. That's a good rating. I'm with you. I agree. 8.9 is good. 

Daniel: I think it's the highest score for an episode. 

Farbod: I mean, it's just great. And I was going to make a joke earlier about how these are the good bacteria there the probiotics. But I decided to keep that to myself. 

Daniel: Yeah, you probably should.

Farbod: Well, now, I feel bad.

Farbod: But I think that's the episode before we wrap up. You know, we promised to do something so I wanted to try to do something right here real quick.

Daniel: Hit me with it. 

Farbod: I'm gonna try. All right, so we're talking about 3D printing, has a lot of benefits. It's easy, its efficient. It allows you to do stuff in different geometries and for the most part, we've been able to accomplish it for polymers as plastics and metals. But Ceramics, that's where we've struggled in the past. It's difficult to get them in a shape that can be easily 3D printed and other attempts at doing this, have resulted in not such great success. You know the part that you end up getting usually shrinks because of the precursor that's in it and it cracks so you're really losing out on any of the benefits that you're supposed to get what these folks have done which is so impressive is use this precursor material that has those right properties to be 3D printed and the precursor materials actually bacteria. 

Farbod: Specifically, its bacteria that when treated with urea, it turns into calcium carbonate, having bone like properties. So, you're getting all those mechanical properties that you would want from mineral like, Bone. You can use it to restore art. You can use it to restore the environment with the coral reefs or replace bones. How's that?

Daniel: I think you got it, man.

Farbod: I tried I really did. 

Farbod: But yeah, I think that's the episode. What do you think? 

Daniel: Yeah, let's wrap it here.

Farbod: All right, everyone, thank you so much for listening. And as always, we'll catch you in the next one. 

Daniel: Peace,


That's all for today The NextByte Podcast is produced by Wevolver, and to learn more about the topics with discussed today visit Wevolver.com. 

If you enjoyed this episode, please review and subscribe, via Apple podcasts Spotify or one of your favorite platforms. I'm Farbod and I'm Daniel. Thank you for listening and we'll see you in the next episode.

More by Farbod Moghaddam

Hello and thank you for visiting my profile! I'm a recent Mechanical Engineering graduate from George Mason University currently employed as a Device Engineer with a focus on automation at a leading international IoT company - Alarm.com. During my undergraduate career, I worked on sensor developme...