Natural beetle juice outperforms Teflon as a lubricant
No matter how good a design humans have come up with, chances are nature has beaten us to it, and done a better job to boot. The latest innovation to join that list is lubricant, with researchers discovering that beetles naturally lubricate their knees with a strange substance that works better than Teflon.
For vertebrates like us, joints are internal, so they can be neatly encased in liquid lubricants. But that’s not the case with insects – having exoskeletons means their joints are exposed to the outside air. Exactly how they keep them lubed up has remained largely unexplored.
So for the new study, researchers at the Christian-Albrechts University of Kiel and Aarhus University wanted to find out. The team examined the knees of the darkling beetle under a scanning electron microscope, and found that the area where the femur and tibia meet is covered with pores, which excrete a lubricating substance.
The team conducted chemical analysis of the substance and found that it’s mostly made up of proteins and fatty acids. Next, they tested the material as a lubricant, placing it between two glass surfaces and rubbing them together at speeds, loads and pressures that would be in the range of a beetle’s regular walking.
And sure enough, the coefficient of sliding friction was much lower for the beetle lube than for two glass plates with no lube. The natural stuff outperformed vacuum grease by a wide margin, and even narrowly pipped polytetrafluoroethylene, commonly known as Teflon.
The beetle juice had some other strange properties too. It’s not a liquid exactly, but more of a “semi-solid.” When it’s extruded from the pores, it tends to fragment easily, which seems to help it cover a wider area more efficiently and penetrate into small gaps.
The team says that this natural lubricant could be useful for small-scale robots and prosthetics, for which conventional lubricants aren’t particularly well-suited. While it’s not exactly practical to try to farm the lube from live beetles, the work could lead to new synthetic versions inspired by the real thing.
The research was published in the journal Proceedings of the Royal Society B.