Using a modified atomic force microscopy (AFM) technique, researchers from Clarkson University (Potsdam, NY) have recorded sub-nano sounds emanating from inside living insects.

The researchers were able to record oscillations of very faint amplitude—less than the size of a single atom—at frequencies of up to 1000 Hz. Previously, the highest frequency recorded of an insect’s insides was 5 Hz.

Led by Igor Sokolov, director of the Nanoengineering and Biotechnology Laboratories Center at Clarkson University, the researchers recorded the sounds by touching the surface of the insects with an AFM probe. Traditional AFM is used to image biological samples by touching the sample’s surface with a nanosized probe.

Sokolov’s team made several changes to this technique to increase the frequency at which the researchers could listen to the insides of insects.

The first change, said Sokolov, was to create a special staging platform that would hold the insects (flies, mosquitoes, and lady bird beetles) in place. Without this platform, the motion of the live subjects could have distorted the results.

“We also developed an attachment which gives us an opportunity to look at the signals and sounds that have never been seen before by humans,” Solokov told BioTechniques. “This technique allows lateral positioning of the AFM detecting probe with nanometer precision, while detecting vibrations of the surface with sub-nanometer precision.”

The researchers also had to modify the signal recording system to output audio signals instead of a visual image, according to Sokolov.

The researchers hope to use their modified AFM to discover unknown characteristics and physiology traits of insects. The work could be beneficial in better understanding these organisms for their impact on crops and ability to transmit disease.

“We just finished a series of work using this method to study behavioral features of lady bird beetles—the ability to adapt to external signals, learn, relax, forget, and so on,” said Sokolov. “We hoped to hear something new, but were surprised by the richness of the sound spectrum.”

The paper, “Atomic force microscopy to detect internal live processes in insects,” was published online January 27 in Applied Physics Letters.