Can you imagine being able to hear the noise a bacterium makes when it moves between hosts or what a virus sounds like? Thanks to the development of the world’s smallest ear, you may hear these noises someday. Scientists have developed the “nano-ear”- a microscopic particle of gold trapped by a laser beam, which can detect sound a million times fainter than the threshold for human hearing.
Sound a bit Sci-Fi? This is an amazing development for science, but what if this technology gets into the wrong hands and gets used by the wrong people – primarily our enemies?
It’s still at the experimental stage, but this could lead to far more sensitive surveillance microphones in the future. The required laser beam could be carried by a difficult-to-detect optical fiber strand to the sensor. Combined with DSP and advanced acoustic signal processing algorithms, this could represent a major security threat.
We already have listening and viewing devices that can be planted in target locations and people can wear or carry audio listening devices on their clothing, etc. However, all of this requires some work or being within a reasonable range of proximity to your target. In addition, listening/recording quality may not be perfect. How would you feel if the human ear could be turned into a super- sonic listening device?
The concept of the nano-ear began with a 1986 invention known as optical tweezers. The tweezers use a laser beam focused to a point with a lens to grab hold of tiny particles and move them around. They now help researchers inject DNA into cells and manipulate them once inside. These tweezers have become a standard tool in molecular biology and nanotechnology. Optical tweezers can also be used to measure minuscule forces acting on microscopic particles; once you’ve grabbed hold of your particle with the laser beam, instead of moving it yourself, you simply use a microscope or other suitable monitoring apparatus to watch whether it moves of its own accord. That’s where the nano-ear comes in.
Sound waves travel as a forward and backward displacement of the particles of the medium they pass through. In order to detect sound, you need to measure this back-and-forth motion.
In addition to having unprecedented sensitivity, the nano-ear could also calculate the direction the sound came from. It is suggested that three-dimensional arrays of nano-ears working together could be used to listen in on cells or microorganisms such as bacteria and viruses, all of which emit very faint acoustic vibrations as they move and respire.
Biophysicist Lene Oddershede of the Optical Tweezer Laboratory at the Niels Bohr Institute in Copenhagen is impressed and suspects the paper will inspire others in the field to look for sound waves when studying microorganisms. “It’s a really interesting idea, and we could easily do that, but we have never made any attempt to do so,” she says. “I would say this paper’s very inspiring in that sense.” She cautions, however, that the experimental setup will need to be significantly refined to improve its ability to separate sound waves from random molecular movement before the suggested acoustic microscope can become a reality. Still, she is optimistic: “I do believe they can relatively quickly improve the equipment.”
Read story@ sciencemag
Tags: eavesdropping, invasion of privacy, security, spying, surveillance
