Atomically thin membranes enable nanoresonators to achieve extraordinalry wide dynamic range for tiny machines

By Dexter Johnson

Researchers at Case Western University have fabricated nanoelectromechanical system (NEMS) resonators made from molybdenum disulfide that have an extraordinarily broad dynamic range. These nanoscale devices’ range is roughly comparable to that of human and animal hearing. The advance could lead to ultra-low-power signal processing and sensing functions in future electronic and optoelectronic chips, according to the researchers.

Dynamic range—the ratio between the highest level of an undistorted signal (“signal ceiling”) over its lowest detectable signal (“noise floor”)—is essential to all sensing and communication, whether it be sensory organs in animals or engineered devices. It’s usually measured in decibels (dB).

In research described in the journal Science Advances, the Case Western researchers, led by Philip Feng, demonstrated that their NEMS resonators have a dynamic range of up to ~110 dB at radio frequencies up to over 120 megahertz. This dynamic range represents the highest reported to date for vibrating resonators made of two-dimensional (2D) materials and other nanoscale structures, says Feng.

These 2D resonators function like the skin of a drum that vibrates at certain frequencies. When struck by something, such as a molecule or photon, those frequencies change. Measuring those frequency changes makes it possible to identify what has hit the device.

In this research, Feng and his team demonstrated that they can also tune the device by stretching the drumhead membranes using electrostatic forces induced by controlling the number of electrons accumulated in the devices, thus providing it with a fairly wide tunability.

“When fully leveraged, this broad dynamic range will translate into high performance in sensitivity for various physical sensors and transducers enabled by such devices, toward real-time sensing applications,” said Feng. “The unique combination of broad dynamic range and frequency tunability also holds promise for making ultralow-power oscillators that could have both low noise performance and excellent tuning capability.” [READ MORE]