Can dogs smell cocaine?

Searching for explosives with animals and technology

Sniffer dogs - fine noses for more security

If explosives are well concealed, their detection is almost impossible. Unless you can smell them - like the explosives detection dogs that are on the police force in North Rhine-Westphalia. The four-legged friends are real specialists. After a 70-day course, they can identify the smell of explosives.

What sounds like hard work to people is a real joy for explosives detection dogs. Because they learn to search for explosives in a playful way. After each successful exercise, they can run around with their masters through green spaces or fetch sticks.

Because the dogs should notice: Successful searches are rewarded by exuberant play. However, there is one thing the explosives detection dogs must never forget: as soon as they smell explosives, they have to stand still. Because with every wrong movement the charge could go up in the air.

Rats on a humanitarian mission

Incredible, but true: the Belgian Bart Weetjens trains rats to search for explosives in Tanzania. However, not every house and meadow rat is suitable. Only the rabbit-sized Gambian hamster rats are trained here, because they have proven to be extremely robust and capable of learning. The rodents' training goal: They should look for landmines in crisis regions.

And this is how the rats are prepared for their tasks: In the first training units, they are given samples with different substances. Some contain the mine explosive TNT, others do not. If the animals scratch the sample containing explosives, they are rewarded with food.

The animals repeat this exercise until they can safely locate even the smallest traces of explosives. Only then do you go to the training units in the open air. The rats begin their search on a special test plot. As soon as they smell a mine, they stop and scratch the sand. The mine is found.

The trainers of the mine rats are satisfied, because the search with the small animals actually proves to be extremely efficient. Rats are hardly susceptible to tropical diseases, they are inexpensive to keep and, above all, have a decisive advantage over explosive detection dogs: Due to their low weight, there is little risk of them triggering the mines with a wrong movement and causing them to explode.

Searching for explosives with bees

Scientific studies show that bees are also suitable for searching for explosives. In August 2003, American scientists trained with the odor-sensitive animals for the first time. To get the bees excited about the search for explosives, the researchers used a simple trick.

They released gaseous TNT every time they were fed sugar water. The animals quickly realized: where there is explosives, there is also food. Then the scientists released the bees to a test field and the insects did their job quickly and thoroughly. After a short time, the animals had found 90 percent of the hidden explosive devices on the test field.

In order for special forces to be able to salvage the mines, precise details of the location are required. If the bees are equipped with a sensor, the scientists only need to determine where a particularly large number of them are gathering. This is where the landmine you are looking for is located.

The center for mine clearance in Croatia is now also training explosive bees. They are supposed to track down the remaining landmines from the war in the 1990s. The insects are also used to search for explosives at some airports in the USA. The advantage over sniffer dogs: the bees have a finer nose and do not get tired so quickly.

The "smelling" mine detector

What dogs, rats and bees can do, a chemical sensor can do. The advantage of an artificial nose is obvious: While every living being is overtaken by fatigue at some point, chemical and electronic sensors work anytime and anywhere. In addition, the smallest amounts of the substance to be sniffed out are sufficient to trigger an alarm.

Scientists at the Fraunhofer Institute have been researching the development of artificial detectors for explosive substances for over a decade. In 2002 employees of the "Fraunhofer Institute for Chemical Technology" in Pfinztal near Karlsruhe developed an electro-chemical mine detector.

This is able to detect even the smallest TNT concentrations. The device consists of three electrodes to which an electrical voltage is applied. If TNT is in the air, a chemical reaction takes place on the electrodes. This increases the current on one of the electrodes and the device fails. A clear sign: the sensor "smelled" TNT. The research relies on a combination of sensor networks and laser detection.

Research is being carried out worldwide into the development of artificial noses. The technology could be used particularly at airports to detect explosives in luggage in good time and to prevent terrorist attacks. In some areas, the olfactory sensors are already being used, such as in coffee roasting, to detect gas leaks or to detect certain diseases.