The first problem with face masks is that we don't have enough of them. The second is that they're made with unsustainable materials. The third problem is that they're opaque, concealing our expressions; this provides an unpleasantly inhuman appearance and can hinder communication.

The Brooklyn-based design duo of Garrett Benisch and Elizabeth Bridges believe they have a way to solve all three problems: Grow transparent filtration masks out of bio-based materials. Benisch and Bridges, a/k/a Sum Studio, have spent the lockdown conducting experiments which yielded a prototype face mask grown from microbial cellulose. "The prototype is speculative," they write, "but it's backed by science referenced in the writing (see below) that shows it's feasible to be growing filtration material rather than producing it from plastic."

Here are some images along with Benisch and Bridges' project description:

As bio-designers, we often look at moments where synthetic chemistry hits a wall and ask ourselves if this bottleneck would have occurred in a world more invested in bio manufacturing. Our natural world is rife with filters, membranes, and woven barriers that are ready to be utilized or mimicked. While impressive in their own right, the greatest assets of these materials are that they can be made at room temperature, that they are abundant, and that they are bio-compatible and capable of helping the planet rather than harming it.

To prove just how accessible these materials are, we decided to grow our own bacterial cellulose face mask in our home quarantine kitchen while ideating some possible ways that this prototype could be iterated to function just like the melt-blown N95 fabric that is in short supply.

Bacterial cellulose is created by a common bacteria, called xylinum acetobacter, on the surface of a liquid that they inhabit. This bacteria and it's cellulose craftwork can be grown with as little as water, tea, sugar, and a small sample to feed and let flourish. As the bacteria multiply, they knit cellulose fibers into a single membrane that can be harvested and dried as a workable material. Though translucent and smooth to the human eye, microscopic images show the tight web of cellulose fibers that make up this incredible knit.

Once the material is thick enough, it can be removed and hung to dry as a flat sheet. This sheet is flexible and strong, yet easily degrades into the environment. It can be waterproofed and oiled with natural ingredients to have a softness and strength of thin leather. The entire process takes around two weeks; long in its own right, but nothing compared to the geologic timescale of fossil fuels and their environmental cost. With multiple batches staggered in time, one could imagine the production of this material scaling quickly.

The fibers that the bacteria weave are too thin and tight to easily breathe through, but there are existing methods that allow us to engineer around this to cater to individual material needs. In 2008, Virginia Tech Wake Forest Biomedical Engineers Paul Gatenholm and Rafael Davalos placed wax particles of a desired diameter on a bacterial cellulose growth surface. The bacteria were forced to knit around the wax particles creating custom sized microscopic holes after the wax was melted away. It is written that this method could be used to create a scaffold for growing bones and cartilage directly on the body instead of in a bioreactor. The two engineers have even gone so far as to dictate the bacterial growth using electricity.

The prototype pictured here envisions employing the same technique to create a material with equivalent filtration to N95 masks, if not better. This material could be grown in local municipalities, in people's homes, or even within the very hospitals that need them to slash existing supply chain risks. Because the bacteria knit to the shape of the container they are in, products can be grown in specifically shaped molds so that the sheets can be grown to standard specification. With PPE like face masks made from cellulose, the life cycle of the product will match the user scenario. Rather than petroleum plastic masks that are used once and then persist in our environment for years, these masks would compost as easily as household vegetables.

…Bio-manufacturing has made leaps in its short lifespan as an industry, yielding raincoats made of algae, real leather grown without touching a single animal, and more. As we are kept in our homes, our entire species halted by a natural being too small to see, there is no doubt that our future relies on moving forward with nature and not against it.

Xylinum Mask from Garrett Benisch on Vimeo.

See Also:

Sum Waste: A Compostable Pen and Ink System Derived from Materials Found in Sewage