Wide dynamic range is usually part of the price to pay for relatively large-sized detection devices for sound, vibration, and radio waves. But researchers at Case Western University have discovered atomically thin devices that can detect radio waves across wide dynamic ranges even when used in extremely miniature structures. The technology is a candidate for wide-dynamic-range wireless communications across short distances, but at extremely low power levels.
The devices, often described as “drumheads,” are about 100,000 times thinner than the human eardrum. The vibrating transducers have been measured with dynamic range as high as 110 dB for RF signals as high as 120 MHz in frequency. Much larger transducers are typically required for much lower frequencies, such as audio signals detected by human eardrums. Human eardrums normally have a dynamic range of about 60 to 100 dB in the audio frequency range of 10 Hz to 10 kHz, and the dynamic range and detection capability of human hearing quickly degrades outside of this audio frequency range.
The researchers fabricated their vibrating nanoscale drumheads from atomic layers of semiconductor crystals with thicknesses of between 0.7 and 2.8 nm and diameters of about 1 µm. The sensors are formed by exfoliating individual atomic layers from bulk semiconductor crystal and using a combination of nanofabrication and micromanipulation techniques to suspend the atomic layers over microcavities that have been predefined on a silicon wafer. Electrical contacts are made to the devices to complete the electrical circuitry. These miniature transducers are capable of operating with extremely low power levels, about 1 pW, while still achieving better than 100-dB dynamic range.
See “Atomically Thin Device Transmits Signals Across a Broad Frequency Range,” Tech Briefs, Vol. 42, No. 9, September 2018, pp. 30-31.