An infra-red comeback for the beetles

I've always been fascinated by the field of biomimetics. It's always amazed me how researchers involved in that field can rip apart biological systems found in animals and plants and then create new man-made technology that effectively performs the same function.

So you can imagine how interested I was when I read this week that a team of German researchers from the University of Bonn (Bonn, Germany) have concluded that the sensors of black fire beetles might even be more sensitive than un-cooled infrared sensors designed by man!

Apparently, the critters in question use their sensors to detect forest fires, even from great distances, since their wood-eating larvae can only develop in freshly burned trees. Naturally enough, since they have had years of experience in doing so, you might have expected that they would perform the function rather well.

Now, with the help of other researchers at the Forschungszentrum caesar (Bonn, Germany) and the Technische Universität Dresden (Dresden, Germany), the researchers at Bonn have figured out how the beetle's infrared sensor actually works, and they have started to work on building their very own biomimetic copy.

The researchers say that they have discovered that each beetle is kitted out with tiny cuticula spheres, smaller than the diameter of a fine hair that are filled with water that absorbs infra-red radiation very well. When these heat up, the water expands suddenly, and the resulting change in pressure is immediately detected by sensory cells.

One they had figured that out, the researchers had to determine just how sensitive the sensors actually were. Naturally, that led them to think that if they could only put mini transmitters on the beetles, they would then be able to determine how far they flew to a burnt area and from that calculate the minimum radiated heat from the fire that the beetles were be attracted to. But at a length of about 1 cm, the poor beetles were too small to carry a transmitter for long distances.

So the researchers relied on data from an event that happened in August 1925 when a large oil depot in Coalinga, California went up in flames. Reports from that era mentioned that the huge blaze attracted masses of charcoal beetles. Since the fire was in the forestless Central Valley of California, the researchers deduced that the beetles must have flown in from large forests on the western foothills of the Sierra Nevada about 130 kilometers away.

The results of their calculations from that data indicate that infrared sensors of the beetles may be able to detect infra-red radiation better than any man-made uncooled infrared sensors currently available on the market.

Rather cool stuff, I thought. But better yet, if the researchers really can build a biomimetic replica of the beetles' sensors, the infra-red detector based on the beetles' biology might change the way we detect forest fires, or detect leaks in petrochemical plants, forever.