UK engineers develop bee-based security device

Trained sniffer bees are the key components of new technology that could stop terrorists in their tracks

Honeybees appear to be simple creatures, buzzing from flower to flower and occasionally startling an innocent passerby. The British summer wouldn’t be the same without them and our cakes certainly wouldn’t taste as good. But these unassuming insects also have a hidden talent that could make them one of the UK’s most ruthless and worst-feared weapons against terrorism.

Bee’s knees: the insects have an extremely keen sense of smell

Two years ago, the government funded a project to harness the olfactory ability of bees in detecting trace vapour to catch terrorists and drug smugglers. A group of researchers in Hertfordshire quietly went to work on a sensor that could do just that. In the course of their research, they discovered that honeybees have an even keener sense of smell than anyone first expected. The device they finally came up with astonished security experts, both for its radical approach and for its levels of accuracy.

’Our sensor integrated live honeybees as the main component,’ said lead researcher Mathilde Briens. ’For a long time people really wouldn’t believe that this was serious work and, even now, many people are amazed by what we’re doing – we usually get a few smiles and often some raised eyebrows.’

Under the government contract, Inscentinel, a spin-out of Rothamsted Research, developed a portable handheld sensor known as the VASOR136 (volatile analysis by specific olfactory recognition). The system can hold 36 trained bees gently restrained in six cassettes inside the device. Each is taught to recognise a particular odour and associate that smell with a food reward.

During operation, a fan draws in air from whatever is being examined and passes it over the bees. If the sample contains the substance the bees are trained to detect, it elicits a proboscis extension reflex response (PER) and the bee sticks out its tongue in expectation of food. When detected, an integrated display provides an immediate read-out of the bee’s reaction. If enough bees respond, an alarm is triggered to warn of dangerous substances in the air.

’We see the bee more like a tool in the machine rather than an insect,’ said Briens. ’Combining biology and engineering together like this makes the system far more reliable. For instance, we know there are a lot of issues with sniffer dogs because of their relationship with the dog handler. If you use some engineering instead, it makes the human factor disappear.’

According to the researchers, honeybees are ideal detectors because they are inexpensive, widely available and can be trained within minutes. They also have extremely low limits of detection, with trace vapours being picked up in parts per trillion levels, comparable to the accuracy of a sniffer dog. But developing the technology to work alongside the bees proved to be a challenge for the team.

Hive of activity: 36 trained bees are held within the device

Marc Bax, an engineer at product development consultancy, Panchromos, was brought in to help develop a solution. ’When I came along, the researchers already had a proof-of-principle device: this had three bees taped down in front of a camera and by using image-recognition software on a computer, they could detect PER events… remit was to build a hand-held battery-powered device, so using a camera was out of the question.’

For a long time people wouldn’t believe that this was serious work and, even now, many people are amazed

Instead, Bax integrated photo sensors and microcontrollers into each bee holder. When clipped into a six-bee cassette each of the bee holders face an infrared light-emitting diode (LED). A PER causes a brief interruption to the infrared beam, as does movement from the bee’s antennae that can let the operator know whether the bee is still active. Alongside this, heat resistors are used in each holder in order to keep the honeybee at the optimum operating temperature of between 10 to 12oC.

’We needed a few tens of cassettes and, as they are a lot larger then the bee holders, injection moulding was not an attractive option here. So the mechanical parts were instead made by selective laser sintering and machining and the clip-on covers were thermoformed. Each cassette also contains a microprocessor – it controls and reads the bee holders and communicates higher-level data up to VASOR display – allowing us to easily make alternative devices containing more than six cassettes or devices with a remote display,’ said Bax.

Inscentinel stresses that the honeybees are not harmed when inside the sensor and after their shift, they are released from their holder and back into their hive. ’You have to take a lot of things into consideration when integrating live creatures into a device,’ added Bax. ’As an engineer, it was a new challenge for me – I only have to think about the discussions we had around the conference table at Inscentinel. Apart from cookies and cups of tea on the table, there were always a number of bees wiggling at you from their holders.’

The group have already trained their honeybees to detect a wide variety of explosive compounds and mixtures, including Semtex, C4, PE4, TNT, DMNB and gunpowder.

They have also been successful in training their bees to detect hydrogen peroxide, which is one of the compounds known to be used in home-made explosives.

According to Briens, in a test for the UK Office for Security and Counter Terrorism, the VASOR136 compared favourably with existing detection technology. The design of the trial was adapted from an aviation check-point protocol used in tests for trace detection equipment. Control measurements were conducted using gas chromatography-mass spectrometry (GC-MS) analysis of the explosive samples to establish the concentration detected.

Fly catcher: bees could prevent terrorists becoming airborne

The VASOR136 was able to detect two explosive materials and GC-MS analysis revealed that the concentrations in the head space generated by the explosive samples were around 50ppb.

According to Briens, the rival device was unsuccessful in detecting this level on the day. Insentinel claims its bees can be trained to detect a single component of the explosive material, meaning they can detect it even if the composition varies, as is the case with Improvised Explosive Devices (IEDs).

Bax believes that the results prove the concept is a valid one and he would now like to see the system used on a wider scale. ’Merging biology and technology in this way could be the way forward,’ he said. ’If you could achieve the same result with electronic components then that would greatly simplify the system, but the point is that it’s very difficult to reach the same level of sensitivity with a purely electronic and chemical device.’

So long as nature’s ingenuity continues to elude engineers, the solution may be in combining the two. As Inscentinel has shown, relatively simple technology used in combination with nature’s complex solutions could be just what’s needed to bridge the technological gap and help solve some of society’s most pressing problems.

insect innovation

Trial suggests that honeybees could also be trained to diagnose disease

The olfactory ability of honeybees isn’t limited to security applications. In a collaborative study with the London School of Hygiene and Tropical Medicine, researchers at Inscentinel proved that bees could also be used to diagnose disease.

During a trial, honeybees were trained to recognise volatile compounds from Mycobacterium bovis BCG – a micobacteria very close to Tuberculosis but safer to handle.

The trained bees were found to differentiate vapours from Mycobacterium bovis BCG from those of the environmental mycobacteria.

According to the research group, implications of the research could be wide-reaching, particularly for developing countries that have very little access to expensive medical equipment.