US engineers have developed a system that uses ordinary WiFi to easily detect weapons, bombs and explosive chemicals in bags with nearly 100 per cent accuracy, demonstrating low-cost technology for security screening. The suspicious object detection system is easy to set up, it reduces security screening costs and avoids invading privacy, whereas the traditional screening typically requires high staffing levels and costly specialised equipment.
“This could have a great impact in protecting the public from dangerous objects,” said Yingying (Jennifer) Chen, Professor at the Rutgers University at New Brunswick in New Jersey, US.
This low-cost system requires a WiFi device with two to three antennas and can be integrated into existing WiFi networks. The system analyses what happens when wireless signals penetrate and bounce off objects and materials. According to the researchers, WiFi, or wireless, signals in most public places can penetrate bags to get the dimensions of dangerous metal objects and identify them, including weapons, aluminium cans, laptops and batteries for bombs. WiFi can also be used to estimate the volume of liquids such as water, acid, alcohol and other chemicals for explosives.
For the study, the team conducted experiments with 15 types of objects and six types of bags and demonstrated detection accuracy rates of 99 per cent for dangerous objects, 98 per cent for metal and 95 per cent for liquid. For typical backpacks, the accuracy rate exceeded 95 per cent and dropped to about 90 per cent when objects inside bags were wrapped, Chen said. The results were presented at the 2018 IEEE Conference on Communications and Network Security held in Bejing.