To make a better sensor, just add noise

Date:
September 3, 2020
Source:
Penn State
Summary:
Adding noise to enhance a weak signal is a sensing phenomenon common
in the animal world but unusual in manmade sensors. Now researchers
have added a small amount of background noise to enhance very weak
signals in a light source too dim to sense.



FULL STORY ========================================================================== Adding noise to enhance a weak signal is a sensing phenomenon common
in the animal world but unusual in humanmade sensors. Now Penn State researchers have added a small amount of background noise to enhance
very weak signals in a light source too dim to sense.


==========================================================================
In contrast to most sensors, for which noise is a problem that should be suppressed, they found that adding just the right amount of background
noise can actually increase a signal too weak for sensing by normal
sensors, to a level that can reach detectability.

Although their sensor, based on a two-dimensional material called
molybdenum disulfide, detects light, the same principle can be used to
detect other signals, and because it requires very little energy and
space compared to conventional sensors, could find wide adaptation in
the coming Internet of Things (IoT). IoT will deploy tens of millions of sensors to monitor conditions in the home and factories, and low energy requirements would be a strong bonus.

"This phenomenon is something that is frequently seen in nature,"
says Saptarshi Das, an assistant professor of engineering science and mechanics.

"For example, a paddlefish that lives in muddy waters cannot actually
find its food, which is a phytoplankton called Daphnia, by sight. The paddlefish has electroreceptors that can pick up very weak electric signal
from the Daphnia at up to 50 meters. If you add a little bit of noise, it
can find the Daphnia at 75 meters or even 100 meters. This ability adds to
the evolutionary success of this animal." Another interesting example is
the jewel beetle, which can detect a forest fire at 50 miles distance. The
most advanced infrared detector can only detect at 10 to 20 miles. This
is due to a phenomenon these animals use called stochastic resonance.

"Stochastic resonance is a phenomenon where a weak signal which is below
the detection threshold of a sensor can be detected in the presence of
a finite and appropriate amount of noise," according to Akhil Dodda,
a graduate student in engineering science and mechanics and co-first
author on a new paper appearing this week in Nature Communications.

In their paper, the researchers demonstrate the first use of this
technique to detect a subthreshold photonic signal.

One possible use being considered is for troops in combat. Army personnel
in the field already carry very bulky equipment. It is unfeasible to add
the heavy, power-hungry equipment required to enhance a subthreshold
signal. Their technique is also applicable in resource-constrained
environments or beneath the ocean where people want to monitor very
weak signals. It could also be used in volcanic locations or to monitor earthquakes in time to give an alarm.

"Who would have thought that noise could play a constructive role in
signal detection? We have challenged tradition to detect otherwise
undetectable signals with miniscule energy consumption. This can open
doors to a totally unexplored and ignored field of noise enhanced signal detection," said Aaryan Oberoi, a graduate student from the Department
of Engineering Science and Mechanics and co-first author on the paper.

Their next step is to demonstrate this technique on a silicon photodiode,
which would make the device very scalable. Any state-of-the art sensor
can be enhanced by this concept, Das says.


========================================================================== Story Source: Materials provided by Penn_State. Note: Content may be
edited for style and length.


========================================================================== Journal Reference:
1. Akhil Dodda, Aaryan Oberoi, Amritanand Sebastian, Tanushree
H. Choudhury,
Joan M. Redwing, Saptarshi Das. Stochastic resonance in
MoS2 photodetector. Nature Communications, 2020; 11 (1) DOI:
10.1038/s41467- 020-18195-0 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200903162041.htm

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