Researchers at Case University of the Western Reserve, located in Cleveland (Ohio, USA), are creating a device for hearing like cats that is ten billion times smaller than the human eardrum.
The team is developing this device, in the shape of a patch, which is very thin and can receive and transmit signals over a radio frequency range much greater than what humans can hear with our ears and which, however, felines can capture.
Thus, it seems quite likely that these advances could contribute to making a next generation of communication and sensory devices of very low power that are smaller and have greater ranges of detection and adjustment , according to the researchers.
“Detection and communication are key to a communicated world,” explains Philip Feng, associate professor of electrical and computer engineering and author of the article published in the journal Science Advances . “In the last decades, we have been connected with highly miniaturized devices and systems, and we have been looking for smaller and smaller sizes for those devices, ” he continues.
Dynamic range
The challenge is indeed that miniaturization, and also achieve a wider dynamic detection range for small signals, such as sound, vibration and radio waves. Dynamic range is the difference in sound pressure level that exists between the softest and loudest sounds that we can hear. And what is it in the case of the human ear? Because, for example, normally we are not able to detect the sound of a butterfly flapping and there are others, such as the firing of a firearm, that we cannot bear without affecting our health (they can damage the protection mechanisms of the ear). As these researchers point out, our eardrums typically have a dynamic range of approximately 60 to 100 decibels in the 10 Hz to 10 kHz range , and our hearing ability declines rapidly outside this frequency range. Animals such as the cat or the beluga whale, they explain, can have comparable or even wider dynamic ranges in higher frequency bands.
“Ultimately, we need transducers – devices capable of transforming or converting an input energy manifestation into one different from the output energy – that can handle signals without losing or compromising information both at the ‘signal ceiling’ (the highest level of a signal without distortion) as in the ‘noise level’ (the lowest detectable level) ”, emphasizes Feng.
The nanoscale vibratory patches that Feng and his colleagues have developed are made of atomic shells of semiconductor crystals with diameters of just one micron. This work was not geared towards specific devices currently on the market, the researchers note, but rather focused on elements that are important to transducers. These transducers could be developed over the next decade , but by now Feng and his team have already demonstrated the capabilities of their key components, the atomic layer patches or resonators, on the smallest scale ever worked on. Until now, that range had only been reached by much larger transducers operating at much lower frequencies – like the human eardrum, for example.
