Tech Briefs Magazine - August 2023 - 14

Q & A
How to Diagnose an Ailing Bridge
Dr. Fei Lu is co-lead
of a Drexel University
team that has developed
a solar-powered wireless
sensor system that can
continuously monitor
bridge deformation and
could be used to alert
authorities if the bridge
performance deteriorates significantly.
Tech Briefs: What inspired you to
work on this project about the bridge
sensor?
Dr. Fei Lu: I am the co-chair of this
project, which was started by Doctor Ivan
Bartoli in our civil engineering department.
Our vision is to utilize a wireless
sensor to monitor the health, the real
time status, of bridges. And based on this
collected information, we could estimate
the health status of the bridge to do any
necessary maintenance.
Tech Briefs: Let me get into a few
technical details. First the power system;
about how much power does
this take?
Lu: The sensor itself is low-power and
energy-saving. The power for the sensor
board itself is in the range of one watt or
even less. We use a combination of solar
power and a battery. Our battery can, on
its own, support the sensor to work continuously
for two weeks without any sun.
Also, because everything is installed outside,
we had to consider severe weather.
Our box and all the connections in the
electrical system are designed to operate
in severe environments.
Tech Briefs: So, the solar panel
charges the battery, and the battery
runs the system, is that it?
Lu: Yes, that's right.
Tech Briefs: If the box is sealed
against the environment, how is the
output data transmitted and how
does the sun get to the solar panel?
Lu: The box is plastic - it's transparent
to the gigahertz-range electromagnetic
waves we use for our transmitter. As
far as the solar panel, it's mounted outside
of the sensor box, and is connected
to the rest of the system by wires through
a watertight opening.
Tech Briefs: Would you transmit
intermittently to save energy, or
continuously?
Lu: It depends on the programming.
You can program it to receive the signal
continuously or you can program it to
ask the sensor to sleep for a while to save
energy - you can ask to send a signal every
few minutes, or every hour, or every
other day.
Tech Briefs: So, once you have good
signals, how do you decide what's
normal for the bridge and what's not
normal?
Lu: We haven't gone into that level of
data analysis yet.
Tech Briefs: What are your plans for
the future?
Lu: We've talked about using drones
together with our sensor box. If the box
is attached to a bridge, you can have continuous
monitoring. But, if the signal is
really bad, you can send in a drone with
a camera to see what's happening. You
could then decide whether to send a person
to further inspect the structure.
To read the full interview, visit www.
techbriefs.com.
14
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Tech Briefs, August 2023
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Tech Briefs Magazine - August 2023

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