If many millions of years of evolution is good for anything, it is to develop microscopic structures that perform astounding tasks, such as the marvelous biology of insects. One of these structures are the ears of the lesser wax moth (Achroia grisella), whose mating behavior involves ultrasonic mating calls. These can attract the bats which hunt them, leading to these moths having evolved directional hearing that can pinpoint not only a potential mate, but also bat calling sound.
What’s most astounding about this is that these moths that only live about a week as an adult can perform auditory feats that we generally require an entire microphone array for, along with a lot of audio processing. The key that enables these moths to perform these feats lies in their eardrum, or tympanum. Rather than the taut, flat surface as with mammals, these feature intricate 3D structures along with pores that seem to perform much of the directional processing, and this is what researchers have been trying to replicate for a while, including a team of researchers at the University of Strathclyde.
To create these artificial tympanums, the researchers used a flexible hydrogel, with a piezoelectric material that converts the acoustic energy into electric signals, connected to electrical traces. The 3D features are printed on this, mixed with methanol that forms droplets inside the curing resin, before being expelled and leaving the desired pores. One limitation is that currently used printers have a limited resolution of about 200 micrometers, which doesn’t cover the full features of the insect’s tympanum.
Assuming this can be made to work, it could be used for everything from cochlear implants to anywhere else that has a great deal of audio processing that needs downsizing.
(Heading image: Mapping of the displacement of a tympanum of the lesser wax moth (Achroia grisella). (Credit: Andrew Reid) )
5 thoughts on “3D Printing Bio-Inspired Microphone Designs Based On Moth Ears”
UV curable rubbers like the Kodak Flexcel NX printing plate might be able to provide the resolution and flexibility needed.
Very interesting indeed. However, it’s important to note that the required lifetime of these moth ears is one week which may mean our efforts to duplicative them may have suffer from very short working lifespans as well. It’s still really cool though.
That’s the whole life of the moth though, it doesn’t necessarily follow that parts of it would not be viable for much longer time spans.
For instance, I have a knife with a stag horn “scale” grip on the handle. It is around 50 years old. A stag sheds antlers yearly, a stag lives around 15 years naturally. So is it 50 or 3 times the intended life that the horn lasts for? Furthermore, there will be artifacts made of stag horn 150 years old, capable of being used, maybe the old family carving knife, brought out for special dinners. Then archaeologists will turn up the occasional stag horn pick from sites with exceptional preservation conditions, thousands of years old. We even have hide/leather that old, should you question me picking a “hard” part.
It doesn’t even as a replication have organic matter subject to rot or consumption by micro or macro organisms.
I would think that human applications would need to be quite a bit larger to operate in the much lower frequencies that we hear. 40Hz-6kHz or so should suffice to hear even the squeakiest of toddlers. Nobody is missing that high pitched CRT whine, right?
Those fluttering shadows are annoyance in summer soon to make me do subtraction in mothamatics.
This makes me wonder, they should study their flight tactics.
It’d make a drone nearly impossible to shoot down!
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