A group of experts used black silicon to create a surface that resembled a tiny "bed of nails" (nanopillars), which physically rip bacteria apart. The nanostructure of this black silicon is very similar to that of dragonfly wings.
How the bacteria gets killed by nanopillars dragonfly model (c) acsh.org
It is widely thought that a "bed of nails" surface destroys bacteria through puncturing the cell wall. However, in a study
made by a team of Australian and Nigerian researchers demonstrated that an entirely different killing mechanism may be at play.
In the model with synthetic "bed of nails" surfaces, nanopillars are produced with equal height. However, a closer examination further demonstrated that the bacterial membrane does not come into direct contact with the nanopillars.
From the observation from the dragonfly wings model, nanopillars do not have the same height. Thus, the bacteria (E. coli) attach to the nanopillars via structural molecules secreted by the bacteria, known as "extracellular polymeric substances" (EPSs), as well as by "finger-like" extensions.
Nanopillars similar to Dragonfly wings (c) acsh.org
Once the bacteria land on the surface, they are subjected to adhesive forces. These can deform the bacterial membrane, but by themselves, probably do not cause the bacteria to rupture.
In the dragonfly wings model, the bacteria are essentially caught in one of those sinister traps. If they don't move, the bacteria might survive, but when they do, shear forces pull on the EPSs, ripping the membrane apart. This results in a fatal leakage of cellular contents, which causes the cell to deflate like a balloon. Only after the cell is dead do the nanopillars penetrate it.
Though there are still limitations in the study, knowing how nature works will help experts mimic it. It's also a good explanation why dragonfly wings are surprisingly clean.