Using common WiFi, this low-cost suspicious object detection system can detect weapons, bombs and explosive chemicals in bags, backpacks and luggage. ... WiFi can also be used to estimate the volume of liquids such as water, acid, alcohol and other chemicals for explosives,WiFi, or wireless, signals in most public places can penetrate bags to get the dimensions of dangerous metal objects and identify them, including weapons, aluminum 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, according to the researchers. This low-cost 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.

1. WIFI SIGNALS TO DETECT
BOMBS
AND
CHEMICAL EXPLOSIVES

2. Contents
• Introduction
• Requirement
• Working
• System overview
• Two Wi-Fi antenna Setups
• Object Risk Estimation
• Conclusion
• References

3. INTRODUCTION
 The growing needs of public safety urgently require
scalable and low-cost techniques on detecting dangerous
objects hidden in baggage.
 Traditional baggage check involves either high manpower
for manual examinations or expensive and specialized
instruments .

4.  A system have developed that uses ordinary Wi-Fi to easily
detect weapons , bombs and explosive chemicals in bags
with nearly 90 per cent accuracy , demonstrating low-cost
technology for security screening.

5. REQUIREMENT
 A Wi-Fi device
 2 to 3 antennas
 A Wi-Fi device with 2 to 3
antennas and can be
integrated into existing Wi-
Fi networks with low-cost
and deployment efforts ,
making it more scalable
and practical than the
approaches using
dedicated instruments.

6. WORKING
• This approach uniquely separates the wireless interface
caused by two influencing factors of objects
i.e., material and shape
• To identify different materials we exploit the Wi-Fi signal
transmitting through or bypassing the objects , which
result in different characteristics like absorption ,
refraction and reflection in CSI values from antennas and
their difference.
• We can estimate its shape (width and height)or volume
based on the finding that the strength of the reflected
signal is proportional to the reflection area of the object.

7. CSI(Channel State Information)
• In wireless communications , channel state information
refers to known channel properties of a communication
link.
• This information describes how a signal propagates from
the transmitter to the receiver and represents the
combined effect of scattering ,absorption and power decay
with distance

9. System overview

10. TWO ANTENNA SETUPS

11. Object Risk Estimation through Reflection-
Based Object Imaging
1. Extracting Reflected Signal from CSI Complex

12. 2.Volume Estimation for Liquid Objects in Baggage

14. CONCLUSION
• To detect the suspicious objects using Wi-Fi technology .
• No installation of high-cost security checking's
infrastructures .
• It can estimate the risk level of the object.
• Extensive experiments are conducted with 15 objects and 6
bags over a 6 month period. The result show that this
system can detect over 95% dangerous objects in different
types of bags and successfully identify 90% dangerous
material types.

15. REFERENCES
• P. MAZZEI, “Florida school, on edge since shooting, requires students to
carry clear backpacks,” https://www.nytimes.com/ 2018/03/21/us/florida-
school-shooting-clear-backpacks.html, 2018.
• https://ieeexplore.ieee.org/document/8433142