Coral reefs from the 3D printer

With your patented process, Mineral Direct Laser Sintering, you can recreate elements of a coral reef. How did you come up with this idea?

David Manjura: I saw that many companies were using 3D printing to produce corals. And they've been doing it on a large scale for over 10 years. You hardly noticed it. But if you looked into 3D printing, you could see that coral reefs were suddenly being made out of concrete, plastic and all kinds of materials. These were sunk into the sea in the great hope that the coral larvae would settle on them and the reefs would grow. I have found that the perlite we use is much better and more suitable and also more ecologically beneficial than some concrete. This can dissolve at some point. And of course it's better than plastic, because we don't need any more microplastics in the sea! So the idea was quickly born to test corals from our pearlitic 3D printing process and then to go out into the wider world and work with universities to conduct further research.

You brought us one of these elements, a cube made of organic shapes, very bright. It looks a bit like light-colored quartz sandstone. What exactly is inside, what kind of material is it? And is it environmentally friendly?

David Manjura: That's right, it looks like quartz stone. It's a volcanic rock, it's also called perlite. Chemically, it is mostly SiO2, so it is composed like sand. It is more environmentally friendly than other typical materials because we do not use any binding agents. Normally, when you try to shape a material in any way, you need some kind of bonding. We actually use a laser, laser sintering to be exact. It's more environmentally friendly. Take concrete, for example. To produce concrete, we need to generate 1,500 degrees, which is a very high temperature. Huge plants are used for this. We do the whole thing locally. We call the process selective laser sintering. This is a selective laser that only melts at the points where it is needed and does not heat up the entire room. In this way, we can selectively melt this component using only electricity, which as we know is much more advantageous than using natural gas, crude oil or other negative energy sources, for example. We have a solar system on our roof, so we have 100% solar power. From an ecological point of view, that's a good thing.

How do you ensure that this structure of your pressure elements supports the growth of the corals particularly well?

David Manjura: We started working with the University of Oldenburg. They needed substrates to create small patterns. Previously, they used stones and placed the coral larvae on them. But these stones were always different, sometimes a bit more porous, sometimes a bit more open. What we were able to do is to create different types of porosity with this fusion by the laser. We can make it glassy with a smooth surface or keep it very porous, and everything in between. Our little coral larvae quickly become divas. They don't want it too smooth, they can't really cling to it. But if it's too porous, then they disappear between the pores and have no chance of actually developing. We have been able to adjust it in such a way that the larvae attach themselves optimally and get enough light. So we have recreated the optimal growth environment for these corals by artificially creating and imitating it. It is therefore an imitation of what they need. Normally it is calcareous material that makes the corals grow. As the sea gets warmer, it becomes more acidic and then the lime decomposes. Our material is not attacked by the acid, so we give it the starter or booster. This gives the corals a good basic structure that is not destroyed and they can reproduce and build up much faster.

I can imagine that it took you a few development steps to get there. How did you get there?

David Manjura: The path was rocky, just like the stones. There were ups and downs, of course. You have to find the right people and the right universities. We also carried out a number of tests in which the structure of the material was crucial. The standard structure of coral was not necessarily suitable. It had to be this gyroid structure, a mathematical structure. This offers many advantages, including anchoring. We can screw it in without concrete or anything like that and it holds on by itself. The wave movements under water help to compact the sand in the pores further and further, making the whole thing stable. Another topic was the developmental stages. I'm not a biologist, I'm a materials engineer myself. That means I first had to get to grips with biology in order to understand what these little animals need in order to grow optimally.

You worked with universities, but also with marine biologists. Do you speak the same language or what were the challenges you encountered?

David Manjura: Well, the main challenge is that everyone has a different view and a different approach. We didn't just work with institutions either. Of course, I also asked those who are already using 3D printing successfully. An affinity for 3D printing is relevant in order to understand and know the production method, to be able to estimate the prices and to know what is possible. The biggest problems are always communication, understanding each other and, of course, the time frames. We are a start-up, we are quite agile. The others send us a file, we print it, the next day it's ready and sent off and then it's a case of wait, wait, wait: Wait, wait, wait. It takes a very long time for the whole thing to be tested, for the coral larvae to grow.

Where are these tests carried out?

David Manjura: We mainly do this in the laboratory because the conditions there are much easier to design. We have also started to submerge the corals in the Maldives and carry out regular tests there, in other words to simulate real life, so to speak. But it is much more important to take basic steps in a laboratory environment first. As far as the larvae are concerned, they are hybrid larvae and are specially designed to withstand high temperatures and salt levels. And then, of course, we also have our booster to hopefully get the "super coral" back. That's the goal.

You brought us a cube with an edge length of 15 centimeters. Is that the normal size you work with, or can it be bigger?

David Manjura: It's actually just a small sample piece. We have developed a pilot system in which we were able to produce component sizes of 50 by 50 by 50 centimeters component edge length. We can reproduce exactly this component in the other size. The 15 centimeters simply came about for test series. So it's tradable. I can simply pick it up. I could also have taken the 50 centimeter sample with me, but that would be a bit more difficult to put here and find a place for it. The components are light. A 50-centimeter component would weigh 20 kilograms. When it gets into the water, the pores absorb and it would weigh 40 kilograms, which is about twice as much. So of course I can handle it much more easily under water and then let the whole thing settle. We built a kind of drill that wobbles back and forth in the sand with its edges. This gets the sand into the holes and compacts it downwards. If more sand is added, it remains all the more stable.

We are talking about an exciting application here, namely the reforestation of coral reefs. Does the technology also have other areas of application, what else could emerge?

David Manjura: The fields of application are diverse. It's almost difficult to focus on one. Another step would be to work on surface corals, which we are already doing. The aim here is to improve biodiversity above ground. The aim is to reforest sealed areas. It's a bit like greening facades. In other words, all related systems, because the material serves as a plant substrate. Perlite is normally found in the soil as small white pellets that absorb water and stabilize the pH value. They are necessary for plant growth. We have adapted this, even for very large elements. The next elements will be blocks up to one meter in size, which we are now printing for the next pilot plant. These will then be above-ground elements. But of course we also deal with other exciting technical topics, such as fire protection. The material does not burn, it also withstands the temperature because it is thermally insulating and very light. We are also currently working on stopping lithium fires in lithium-ion batteries, which are mainly used in the automotive industry. In other words, the chain reaction within the individual lithium cells. We have carried out a series of tests in which we can produce quite complex elements that are very suitable for 3D printing in order to encapsulate the individual cells and counteract the fire that occurs in the event of overvoltage or similar.

To what extent can the manufacturing process of mineral 3D printing establish itself across industries and what tips would you give companies that want to start implementing this printing process?

David Manjura: Basically, as I said, it works in many industries. The important thing is to have as concrete a problem as possible and to work on it. I mentioned the topic of fire protection earlier, for example. Currently, however, the focus is also on iron or metal casting and ensuring that the casting is binder-free and that there is no outgassing when hot metals come into play. This means that very thin bars can be produced. This is an example of a clearly solvable problem. It is very relevant to have good communication here. People often tend to judge problems from their own perspective and not think three-dimensionally, i.e. really take advantage of the freedom of form that 3D printing offers. That's why I would say that the most important thing when working across industries is to have very clearly defined communication and the same point of view during the development process. That way, you can achieve a straightforward progression.

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