Which detection methods can leave no room for explosives to hide?

Instrumental testing

Currently, countries around the world are stepping up security inspections and bomb-detection measures at critical facilities such as key government departments, airports, railways, and subways. According to their underlying technological principles, detection technologies can be categorized into X-ray detection, electrochemical detection, electromagnetic detection, neutron detection, laser spectroscopy, and others. In practical applications today, these include X-ray security inspection equipment and ion mobility spectrometry devices.

With the continuous advancement of explosion-proof technology, Raman spectroscopy detectors, X-ray security scanners, and ion mobility spectrometry devices are currently the most commonly used explosives detection equipment.

X-ray technology

Currently, the advanced dual-energy CT detection technology using X-rays has been applied to explosive detection and security screening. Compared with conventional X-ray techniques, this method enables rotational scanning around the cross-section of the object being inspected. The computer then reconstructs an image based on the 360° projection data collected, effectively identifying hidden objects and significantly improving the detection rate of explosives.

Ion Mobility Spectrometer

Faced with increasingly sophisticated and unconventional homemade explosives that are difficult to detect, the global community has been continuously striving to advance the development of explosion-proof technologies. Traditional Ion Mobility Spectrometry (IMS) typically distinguishes between different substances by identifying peaks at various positions on the spectrum and is widely used for detecting trace amounts of chemical weapons, drugs, explosives, and air pollutants. However, when it comes to a new material frequently found in suicide bombs—triacetone triperoxide (TATP)—non-radioactive ion mobility spectrometry detectors are considered more effective. Last year, TATP was the explosive used in the Paris series of terrorist attacks; this homemade explosive also played a central role in the 2005 London subway bombings. Since TATP does not contain nitro groups, it cannot be detected by conventional detectors designed for nitro-based explosives such as DNT (dinitrotoluene) or TNT (trinitrotoluene). The newly developed ion mobility spectrometry detector, however, can not only detect common nitro-based explosives but also enable rapid detection of the homemade explosive TATP.

Currently, commonly used explosion-proof devices are typically designed for close-range use, and some even require direct contact, posing a threat to the safety of personnel in the surrounding area. Therefore, it is highly necessary to develop a safe, effective, and covert long-distance explosion detection technology. In long-distance detection, the equipment generally maintains a distance of several meters to 100 meters from the target object, thereby minimizing potential hazards and enhancing concealment. From a technological development perspective, the main approaches include laser spectroscopy detection, terahertz technology, and millimeter-wave technology.

Plasma Laser-Induced Breakdown Spectroscopy

Looking ahead, portable plasma laser sensors are poised to become a new trend in research and development applications. Reportedly, the University of California, Berkeley has developed an ultra-high-sensitivity plasma laser-induced breakdown spectroscopy sensor that can detect extremely low concentrations of explosives—enabling the effective identification of explosives that have been difficult to detect before they are widely used in terrorist attacks. This sensor is considered to hold significant potential for practical applications.

Time-resolved laser Raman spectroscopy

As an emerging technology, Raman spectroscopy—characterized by its rapidness, high sensitivity, remote sensing capability, and non-destructive nature—can be applied to the rapid detection of inks, documents, drugs, explosives, and other substances. It offers advantages such as speed, simplicity, repeatability, and non-destructiveness. The time-resolved Raman spectrometer represents a groundbreaking innovation, born from the long-term accumulation and continuous innovation in ultrafast pulsed laser technology and time-resolved single-photon detection techniques at the Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences. By employing a time-gating approach, this instrument significantly enhances signal strength, effectively suppresses fluorescence interference and the impact of ambient stray light, and enables analysis from long distances. Consequently, it largely addresses the limitations currently faced by conventional Raman spectrometers when detecting explosives.

The next-generation time-resolved Raman spectrometer can detect a wide variety of substances, including drugs, biological agents, explosives, and hazardous chemicals. It has extensive applications in the security field and can be used at sites such as high-speed railways, subways, train stations, customs checkpoints, and police stations to rapidly identify dangerous liquids, explosives, drugs, precursor chemicals, jewelry and jade, and industrial raw materials.