Tech Briefs Magazine - May 2021 - 28

Sensors

No response

ΔV/V0

0.6

0.4

0.2

Nasal swab
and saliva samples

Negative

0.0
0

100
Time (sec)

200

DNA-RNA hybridization

High response

0.6
0.5

ΔV/V0

0.4
0.3
0.2

Positive

0.1
0.0
0

100
Time (sec)

200

The COVID-19 electrochemical sensing platform.

electrical readout. Both gold and
graphene have high sensitivity and
conductivity, which makes this platform ultrasensitive to detect changes
in electrical signals.
Current RNA-based COVID-19 tests
screen for the presence of the N-gene
(nucleocapsid phosphoprotein) on the
SARS-CoV-2 virus. In this research, the
team designed antisense oligonucleotide (ASOs) probes to target two

regions of the N-gene. Targeting two
regions ensures the reliability of the
senor in case one region undergoes
gene mutation. Gold nanoparticles
(AuNP) are capped with these singlestranded nucleic acids (ssDNA), which
represents an ultra-sensitive sensing
probe for the SARS-CoV-2 RNA.
The researchers previously showed
the sensitivity of the developed sensing
probes in earlier work. The hybridiza-

tion of the viral RNA with these probes
causes a change in the sensor electrical
response. The AuNP caps accelerate the
electron transfer and when broadcasted
over the sensing platform, results in an
increase in the output signal and indicates the presence of the virus.
The team tested the performance of
the sensor by using COVID-19 positive
and negative samples. The sensor
showed a significant increase in the
voltage of positive samples compared to
the negative ones and confirmed the
presence of viral genetic material in less
than five minutes. Furthermore, the
sensor was able to differentiate viral
RNA loads in these samples. Viral load
is an important quantitative indicator
of the progress of infection and a challenge to measure using existing diagnostic methods.
This platform has far-reaching applications due to its portability and low
cost. The sensor, when integrated with
microcontrollers and LED screens or
with a smartphone via Bluetooth or
WiFi, could be used at the point-of-care
in a doctor's office or even at home.
Beyond COVID-19, the team also foresees the system to be adaptable for the
detection of many different diseases.
For more information, contact the News
Bureau at news@illinois.edu; 217-333-1085.

Ultra-Sensitive Flow Microsensors
The sensors could be used in medical applications such as neuroscience and
metabolism processes.
University of Massachusetts, Amherst

team of researchers developed a
thin, ultra-sensitive flow sensor that
could have significant implications for
medical research.
Flow sensors, also known as flowmeters, are used to measure the speed of
liquid or gas flows. The speed of biofluidic flow is a key physiological parameter but existing flow sensors are either
bulky or lack precision and stability.
The new flow sensor is based on
graphene - a single layer of carbon
atoms arranged in honeycomb lattice
- to pull in charge from continuous
aqueous flow. This phenomenon provides an effective flow-sensing strategy
that is self-powered and delivers key
performance metrics higher than
other electrical approaches by hundreds of times.

The graphene flow sensor can detect
flow rate as low as a micrometer per second - less than four millimeters per
hour - and holds the potential to distinguish minimal changes in blood flow in
capillary vessels. The performance of the
graphene flow sensor has been stable for
periods exceeding half a year.
The device is self-powered and holds
the potential to be implanted for longterm biofluidic flow monitoring. To
implant a micro flow monitor like this
one in a small blood vessel is much simpler and safer than existing flowmeters, which are not suitable for low-flow
measurement and need to be installed
in a larger blood vessel. Scientists and
doctors may find it useful for research
and clinical applications such as monitoring the blood flow velocity in deep-

www.techbriefs.com

Cov

ToC

brain vessels to understand the functioning of neurons that control the
flow of blood.
Graphene is the key material in development of the sensor. The unique combination of intrinsic properties of graphene
- such as ultra-high sensitivity, ultra-low
electrical noise, minimal contact electrification with aqueous solutions, outstanding stability in chemical and mechanical
behaviors, and immunity to biofouling -
work together to induce the high performance of the flow sensor.
Next steps for the team include integrating the flow sensor into a self-sustained flow monitoring device and
exploring the application of the device
in healthcare.
For more information, contact Mary Dettloff at mdettloff@umass.edu; 413-545-2500.
Tech Briefs, May 2021

http://www.techbriefs.com http://www.abpi.net/ntbpdfclicks/l.php?202105TBNAV

Tech Briefs Magazine - May 2021

Table of Contents for the Digital Edition of Tech Briefs Magazine - May 2021