a series of experiments on the three-dimensional printability of bacterial cellulose
In this project, I investigated the three-dimensional printability of the bacteria Acetobacter xylinum. It was important to find out how to optimize the conditions the bacteria need to form cellulose and how to maintain a humid climate and a sufficient oxygen supply. According to latest research, it is possible to print bacteria three-dimensionally in combination with hydrogel. The hydrogel not only creates an oxygen exchange and an optimal humidity, but also keeps the bacteria and its nutrient medium in a certain shape. Based on this, I tried to grow bacterial cellulose in different gels. I used a syringe to inject the cellulose into a gel bath. After that I observed its growth.
full concept text
Bacterial cellulose is a versatile material that allows it to be shaped in a variety of ways. Because of its numerous unique properties, bacterial cellulose has been used in food, medical and commercial industries.
One of its great properties, its resistance to tear, is gained from its very fine mesh structure. Due to its good water absorption capacity, it is also flame retardant. There are already quite a few experiments and design ideas with the material. Many have investigated how to control the growth two-dimensionally. The resulting sheets are normally dried and used as a type of leather. The most popular way to produce bacterial cellulose is through the symbiosis of yeasts and bacteria. Like we see it in Kombucha.
However, what about growing the cellulose three-dimensionally?
Wouldn‘t that spare offcuts in the textile industry and therefore save material and sewing effort?
To answer these questions precisely, I looked into the three-dimensional printing capability of the bacteria. It was important to find out which optimal conditions the bacteria need to form cellulose and how to maintain a humid climate and a sufficient oxygen supply. According to the latest research, it is possible to print bacteria three-dimensionally in combination with hydrogel. The hydrogel not only creates an oxygen exchange and optimal humidity, but also keeps the bacteria and its nutrient medium in shape. Based on this, I tried to grow bacterial cellulose in different gels.
The individual gels each have a different composition. They differ in their transparency, stability and in their ingredients. I achieved first results with xanthan, agar agar, hair gel and lubricant gel. I hexed my Kombucha mushroom and filled it into a syringe to imitate the extruder on the 3D printer. The mass was then injected into a gel bath where the growth could be observed. The most successful result was found to be in the lubricating gel, which contained similar ingredients to those in a researched paper on three-dimensionally printed cellulose.
Here, it was possible to remove the compound in its entirety, without the cellulose filament separating. Other experiments were conducted to check the stability of the cellulose in the printed state. Here I traced structures to indicate printability outside the gel bath and to give an idea of the already dried material. But how can we generate more attention for this versatile bioplastic? Could it be used to grow three-dimensional textiles? Could it be a more sustainable alternative to cotton or paper and could it even be produced regionally?
Concept of production and circulation
„Kombo“ is a café that not only functions as a place where people get together, but a place that also introduces its guests to the potential of bacterial cellulose, with the help of technology, products and a holistic concept. The Kombucha Café stands in cooperation with supermarkets from the region, which provide their left-over fruit free of charge. The sugary waste is used as a source of nutrients for the bacteria. The supply varies depending on the season and gives the kombucha liquid an individual taste and colour. Once it has arrived at Kombo, the waste is mixed with the recycled cellulose, bacteria and green tea. The mixture is then poured into a vending machine and 3D printed into a gel bath with the help of a robotic arm. The customer can start the next print by inserting a coin and will then receive an already dried shopping bag made of bacterial cellulose. If at some point the bag is no longer usable, it can be taken back to Kombo. In return, one receives discounts not only on new bags, but also on a take-away drink or a Kombucha culture for fermenting your own drink at home.
Kombo informs its visitors about the origin of the bacteria’s nutrients, the biotechnological way it is grown and different examples in application. The consumer takes an active part in its production, its use and the return into the cycle. In this way, Kombucha serves not only as a trendy refreshment, but as a valuable material of the future.