What are the issues faced with existing filter systems?
The biggest problem with existing filters is that they easily get clogged up. Research is also interested in reducing the amount of energy required in the filtration process. These same issues exist in the natural world, which are resolved by a diversity of highly differing organisms. In a dusty environment, for example, the many particles start to clog up your nose, to which the body responds by generating an increased amount of mucus to remove the particles. If this response does not suffice, you may have to blow your nose. The natural world is full with examples of different filtering approaches.
What biological models are there that we can imitate to improve filter systems?
We have identified six biological systems that remove particles from the air—for reasons including protection, reproduction and feeding. These are: nasal cavities, silk cocoons in insects, spider webs, insect respiration filters, wind-pollinating plants with and plants that deposit fine dust particles. Nasal cavities are very interesting, whose function is to filter out particles in order to protect the lungs. Instead of a sieve or fine net, the human nose employs nasal hair, a special geometric structure and mucus in combination. I have never seen any similar structure implemented in engineered filters. The nose could thus serve as a biological model in efforts to improve existing filters, potentially leading to the development of innovative filter systems.
What are the challenges faced?
Studying the mechanisms involved in biological models can be challenging—implementation as a technical solution even more so. Biological models are uniquely individual, requiring different methods depending on whether the nose, a spider web or a flower, for example, is the object of investigation. First, the filtration mechanisms must be identified and understood; the next step is to recreate these in a prototype. The process can take a while because a lot of data has to be collected, and to get to a working prototype it can take some tinkering around. But I enjoy the challenge.
What research into filter mechanisms and technology is being conducted at the University of Bonn?
We are currently focusing on the silk cocoons of hornet larvae. The larvae spin a web around themselves for protection in the sensitive phase of transforming into a fully grown insect. The silk cocoons appear to have quite interesting filtration properties, but little research has been conducted on this to date. This is exactly what we are looking at in an effort to develop new filters—for mouth and nose protection, for example—based on this biological phenomenon.
