Usually, if you think of the use of paper in the aerospace industry, the only thing you can imagine is folding paper planes to practice your origami skills. But what if someone told you it is possible to use paper to make transparent and strong materials that are part of real airplanes?
Paper has been around for centuries and we all use it daily… Butdaily, but what is it made of? The most popular recipe to prepare paper is called Kraft process.1 The main ingredient is wood, which is cooked to obtain wood pulp. Imagine as if the pulp wasas a soup containing thousands of noodles. These noodles are in fact thick cellulose fibres (diameter of 20-30 μm), and, when dried, they stick together and are the reason behind the strength of paper.2 As these fibres get smaller, they get more tangled (or bonded) between them, making them harder to separate when dried and therefore increasing the strength of the paper.3
Acetobacter xylinum is a bacteria able to produce cellulose fibres 1000 times smaller than the onesthose found in commercial paper. The only thing it asks in exchange is to be fed a lot of sugar (also known as glucose). In return, it assembles together the glucose units into long chains, which result intoin thin cellulose fibres (diameter < 100 nm).4 These cellulose fibres are so small, that scientists calledcall them nanocellulose. It has been measured that a single nanocellulose fibre has a strength between 2 and 6 GPa5, which is superior or equivalent to the strength of materials like glass or steel. And onOn top of that, it is much lighter!6 However, when thousands of bacteria grow nanocellulose fibres, they don’t do it in an orderedorderly fashion. Instead, the fibres are as randomly oriented as cooked spaghetti.