7. BioFabricating Materials

Research & Ideation

The subject for this week's assignment is the exploration of biofabrication: the science/art of creating living materials from natural organisms and processes. We learn how to grow, mold/cast, and cook biomaterials like bacterial cellulose, filmy biopolymers, plant-based leather, to the point where life can become design matter.

What is BioFabrication? What is a biomaterial?

BioFabrication is the process of producing materials/structures/components using living systems, like fungi, cells, or bacteria. A succesful example of biomaterial fabrication is the company Desserto which produces high-quality cactus-based materials, using a cactae that grows everywhere called Nopal, which is also edible.

desserto?

Let's cook.

For this assignment I will (try to) prepare 3 different kinds of biomaterials, one based on bacterial cellulose, another made out of Mycelium, and a third one made from Agar agar, an emulsifying agent taken from red algae.

Bacterial Cellulose Have you ever heard of Kombucha? It is a beverage that consists of either green or black tea, and some sugar, which is fermented by a thing called Scoby which means Symbiotic Culture Of Bacteria and Yeast. If you feed this Scoby it will grow, and it is made out of cellulose, the same material that composes paper, without the hassle of waiting for a tree to grow. The recipe for the Kombucha is very easy but the secret ingredient is a ton of patience, as the Scoby grows very slowly.

• Water: 3 liters
• Scoby starter: ~500ml (Scoby starter is just a chunk of previously grown Scoby)
• Black tea leaves: 18g
• Sugar: 300g

The water is boiled and removed from the flame, the tea leaves are left to steep and then removed, and the sugar is added so it disolves and everything is homogeneus. The mixture is left to cool to room temperature and then the Scoby starter is added, mixed and left in a hot and humid place. The water must be changed, and the scoby fed every 14-15 days in order for it to have a healthy grow.

After some time the scoby is visible and we can take it, cut it and be left to dry using either a mold or just a clean screenprinting screen.

Foto del molde

Mycelium If we could, and we definitely shouldn't, compare plants with fungi, Mycelium would be the roots, and the edible mushroom would be like the fruit. This spongy thick material is great for solid pieces instead of tissue, and it is probably very good for CNC Machining. The basic principle for growing mycelium is to grab an organic substrate like straw or even cardboard (for what I have seen), innoculate it with the fungi seeds and wait for the mycelium to take over the organic material, and basically substitute it, with the possibility to grow edible mushrooms. So we started the process with straw, a kind of yellow grass mostly used for feeding cattle, cut it in small chunks and then added to a pot with boiling water. This process softens the straw, and also eliminates any other micro-organism that could potentialy contaminate the mycelium. After it was cooled down to room temperature, we added it to little molds, in this case this food-safe box, and in-between each layer of straw, we scattered some of the mushroom seeds so it grows in every crease. This mycelium is left to grow in a warm and dark space. In my case I used the incubator I built inspired by the one from my friends at Domingo Club that I use for growing Tempeh. It works by using an off-the-shelf thermostat and heating pads for clothing that I bought online, and the case was designed and built with mdf from MakerCase.

Agar agar The Agar agar is a powder ingredient that's mostly used for making gelatin, as a vegetal alternative, which creates a gel when it gets cold. It is also used as a culture medium as it retains nutrients for bacterial growth. I found the recipe, and had to tweak it for my purposes, in the amazing online library Materiom which has a huge collection of recipes and processes for biomaterials and projects. The ingredients were:

• Agar agar: 15g
• Water: 1liter
• Paper: 70g
• Glycerin: 5g

So the principle of this biomaterial goes like this; the paper (cellulose) fibers give the structure in which the agar agar gels when cold, and the glycerin gives it a little bit of plasticity. The process started by heating water before the boiling point and adding the agar agar powder, then the glycerin and stir. On a separate container with water, the paper is cut in small pieces, and then blended so we have a paste. We mix both containers and simmer for a while, until we get the consistency we need.

Quick

1. What I found is that if we remove the water by boiling, the biomaterial becomes a easy to use paste, which can be put in a mold.
2. If we play with the proportions of each ingredient, we change the outcome, for example, more glycerin gives it a more plastic film, more paper has a papery result, and agar has a gel and crumbly result.

In every process we need a lot of patience and understand what is going on, it may be feeding the living organisms so they grow in the shape we need, or waiting for the mixture to get cold and lose its humidity.

Bonus super extra

From the Computational Couture assignment I got a very good idea for a concept I tried. The parametric design on grasshopper can fill any flat surface with points, which can be removed depending on how far and how strong a field is, and we could also join every point with a curve, which is inside of the area we need, and then maybe we could create a mold on the CNC router to put the biomaterial, let it dry and voila! we have a piece (in theory).

Grasshopper 1

Grasshopper 2

It worked! So the next part is to use the CNC router and try to get the material in the mold.

Pieza final

For next projects I must say that, even though it worked on mdf, the material for the mold would be much better if flexible and non-porous, something like plastic or silicone would work best, but for a first trial, mdf can be cheap and easy to work.

Fabrication files

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1. File: Grasshopper algorithm ↩