The atomically thin drumheads were designed for ultra-low power devices

By Warren Miller,
contributing writer

Miniaturization is the watch word in technology — from
laptops to smart phones to everything in between, the smaller the better. Still,
there has to be a threshold that just cannot be crossed – after all, how much
smaller can it all get? A research team at Case Western Reserve University may
have just set the new standard in miniaturization by developing a drumhead capable of receiving
and transmitting signals over a much greater range of frequencies than the
human eardrum
— and tens of trillions of times smaller.

The new device is so small that it’s 100,000 times thinner
than the human eardrum. They also have recorded the highest dynamic range ever
reported by this type of vibrating transducer, representing a possible
breakthrough in the fields of sensing and communication. Its predecessors have
all been much larger (how could they not be?) and operated within a lower range
of frequencies, a range closer to that which the human ear can detect.

“What we’ve done here is to show
that some ultimately miniaturized, atomically thin electromechanical drumhead
resonators can offer remarkably broad dynamic range, up to ~110dB, at radio
frequencies (RF) up to over 120MHz,” according to Phillip Feng, co-author of a
paper published in last month’s issue of the journal Scientific Advances.
“These dynamic ranges at RF are comparable to the broad dynamic range of human
hearing capability in the audio bands.”

Device trillions of
times smaller than human eardrum offers cat-like hearing.
Image
Source: Case Western University.

Dynamic range, for the uninitiated, is the differential
between a signal’s ceiling and its floor. Typically measured in decibels, the
dynamic range of a healthy human eardrum is about 60 to 100 db. Human hearing
is only effective in frequencies ranging from about 10 Hz to 10 kHz. Housecats,
by comparison, can still effectively hear frequencies in the 100 kHz range. Feline
eardrums are still significantly larger than the Case Western Reserve team’s transducers
as well.

It may be difficult to predict where this type of technology
might ultimately end up, but it has much broader applications than just
‘hearing.’ These tiny resonators might be the key to combining electronic,
mechanical and optical elements- all working together in atomic layer
semiconductor devices. Could they be used to efficiently transform energy from
one form to another and even switch or process data ultra-efficiently?

Now, this is just wild speculation, but if some of the more
unique materials we have recently discovered with piezoelectric properties,
superconductivity, and super-efficient energy storage could be combined we
might see some almost ‘magical’ devices. How about smart mobile devices that
can locate and move to needed energy sources to ‘power-up.’ Or perhaps sensors
that follow signals of interest to their sources to study and report back. Even
tiny mobile bots that communicate with each other and group together to
cooperatively work on and complete tasks might be possible. Perhaps we will
even find that devices with the ability to self-repair and self-replicate are possibilities.
Materials science seems likely to continue to surprise us, hopefully in good
ways.