Researchers at Rutgers University in the US have used standard WiFi with multiple MIMO antennas to detect metals and liquids in luggage rather than using more comlex terahertz wireless systems.
Using WiFI means the detection system is easy to set up, reduces security screening costs and avoids invading privacy such as when screeners open and inspect bags, backpacks and luggage.
“This could have a great impact in protecting the public from dangerous objects,” said Yingying (Jennifer) Chen, study co-author and a professor in the Department of Electrical and Computer Engineering in Rutgers–New Brunswick’s School of Engineering. “There’s a growing need for that now.”
The study – led by researchers at the Wireless Information Network Laboratory (WINLAB) in the School of Engineering – included engineers at Indiana University-Purdue University Indianapolis (IUPUI) and Binghamton University.
The system requires a WiFi device with two to three antennas and can be integrated into existing WiFi networks. The system analyzes what happens when wireless signals penetrate and bounce off objects and materials.
Experiments with 15 types of objects and six types of bags demonstrated detection accuracy rates of 99 percent for dangerous objects, 98 percent for metal and 95 percent for liquid. For typical backpacks, the accuracy rate exceeds 95 percent and drops to about 90 percent when objects inside bags are wrapped, said Chen.
"In large public areas, it’s hard to set up expensive screening infrastructure like what’s in airports,” Chen said. “Manpower is always needed to check bags and we wanted to develop a complementary method to try to reduce manpower.”
Next steps include trying to boost accuracy in identifying objects by imaging their shapes and estimating liquid volumes, she said.
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