Honeybees (Apis Melifera) have a very acute sense of smell, are quick to train, inexpensive to keep and do not take up a lot of space. They can detect extremely low concentrations of volatile compounds—parts per trillion for some chemicals—with very high specificity. This makes them ideal sensors to detect trace vapours, with applications ranging from security screening for explosives to agri-food quality assurance and medical diagnostics.
Bees naturally exhibit a Proboscis Extension Reflex (PER) when they are presented with food: similar to Pavlov’s dogs, they can be conditioned to show a PER when confronted with other highly specific stimuli—such as the presence of a volatile compound. This is the principle behind Inscentinel’s VASOR technology (short for Volatiles Analysis by Specific Odour Recognition).
A dog in a box
When I got involved Inscentinel had already built a first lab-based proof-of-concept model that used a camera and image analysis software running on a PC to detect the PER from three bees. Our brief was the turn this concept into a self-contained hand-held device with 36 bees suitable for practical field trials in airport security. This meant we had to keep the device small and light, could not use a camera, had to create our own clean air, and had to use battery power.
We also had to design a bee-holder: a little cartridge that restrained the bee. No bees were harmed, after their conditioning they would go on sniffer duty for up to two hours before being released back into the hive. The bee-holder had a sensor to detect a PER, a heater to keep the bees at their preferred temperature, and a microcontroller to give complete traceability. Inscentinel was awarded three patents on the bee-holder.