For detecting explosives and improvised explosive devices (IEDs), A simple Paper-based Wireless Sensor is developed by Researchers at the Georgia Institute of Technology. They have developed a prototype wireless sensor capable of detecting trace amounts of a key ingredient found in many explosives. Explosives Detector employs carbon nanotubes and is printed on paper or paper-like material using standard inkjet technology. This wireless explosives detector can be used in large numbers to alert authorities to the presence of explosives, and improvised explosive devices (IEDs).

Wireless Explosives Detection Technology

Explosives Detector with Paper-based Wireless SensorOther types of hazardous gas sensors are based on expensive semiconductor fabrication and gas chromatography, and they consume more power, require human intervention, and typically do not operate at ambient temperatures. Furthermore, those sensors have not been integrated with communication devices such as antennas.

In Wireless Explosive Detector, the wireless component for communicating the sensor information, is a resonant lightweight antenna printed on low-cost photographic paper using inkjet techniques. The explosives sensing component is based on functionalized carbon nanotubes (CNTs), fabricated and tested for ammonia detection sensitivity.

Paper-based Wireless Sensors by Inkjet Priniting

The key to printing components, circuits and antennas lies in novel “inks” that contain silver nanoparticles in an emulsion that can be deposited by the printer at low temperatures around 100 degrees Celsius. A process called sonication helps to achieve optimal ink viscosity and homogeneity, enabling uniform material deposition and permitting maximum operating effectiveness for paper-based components.

Low-cost materials such as heavy photographic paper or plastics like polyethylene terephthalate can be made water resistant to ensure greater reliability. Inkjet component printing can also use flexible organic materials, such as liquid crystal polymer (LCP), which are known for their robustness and weather resistance. The resulting components are similar in size to conventional components but can conform and adhere to almost any surface.

Explosives Detector Wireless Sensor of GTRI

Printing Wireless Sensors for Ammonia Explosives DetectionResearchers used inkjet printing techniques to produce RF components, circuits, antennas, and carbon nanotubes used for sensing explosives. These nanoscale cylindrical structures are about one-billionth of a meter in diameter, or 1/50,000th the width of a human hair, are functionalized by coating them with a conductive polymer that attracts ammonia, a major ingredient found in many IEDs.
Sonication of the functionalized carbon nanotubes produces a uniform water-based ink that can be printed side-by-side with RF components and antennas to produce a compact wireless sensor node. The explosives sensor has been designed to detect ammonia in trace amounts as low as five parts per million.

The resulting integrated sensing package can potentially detect the presence of trace explosive materials at a distance, without endangering human lives. This approach, called standoff detection, involves the use of RF technology to identify explosive materials at a relatively safe distance. The GTRI team has designed the device to send an alert to nearby personnel when it detects ammonia.

The wireless sensor nodes require relatively low power, which could come from a number of technologies including thin-film batteries, solar cells or power-scavenging and energy-harvesting techniques. In collaboration with Tentzeris’s and Wong’s groups, GTRI is investigating ways to make the sensor operate passively, without any power consumption.