By Jonathan Fildes
Science and technology reporter, BBC News
The first thing that hits you when you enter Professor Takamichi Nakamoto's laboratory is the smell.
An odour recorder could be used in the fragrance industry
Wafts of fried beef and onions, the rich smell of Japanese curry and even the obnoxious smell of rotten eggs all mingle together in the cramped room.
But the stench is not the product of an absent-minded professor surrounded by the detritus of late night snacks snatched during marathon experiments.
Instead, the aromas are intimately tied to the Professor's work.
Based at the School of Engineering at the Tokyo Institute of Technology, Professor Nakamoto is building a range of gadgets and sensors which sniff, mix and pump out a range of hundreds of scents.
One of the most ambitious devices his team has built is a sophisticated "odour recorder" which can sniff an object and then reproduce its smell using a host of chemicals.
If you present the recorder with a shiny red apple, the electronic nose will take a cursory sniff, analyse the odour and then draw up a recipe of chemicals needed to recreate it.
When you want to replay the scent, the device mixes the ingredients and pumps the smell of apples back at you.
The odour recorder uses a neural network to learn fragrance recipes
"Our intention is to make all smells reproducible," Professor Nakamoto said. "So, in this case we have combined two techniques: smell detection and smell generation."
At the moment, the prototype can only reproduce certain fragrances, including apples, bananas, oranges and lemons.
But synthesising billions of different smells is still problematic, the professor admits. There is not a small number of "primary" odours from which all others can be created.
Instead, Professor Nakamoto and his team have to load the machine with nearly a hundred vials of chemicals, chosen according to the target odour, which the machine mixes in varying concentrations.
The device does not necessarily mix the right recipe on its first attempt. Instead, it learns the correct ingredients list by comparing the analysis of the target scent with more and more refined concoctions.
The machine "learns" recipes using a neural network, a collection of computer processors that function in a similar way to a simple animal brain.
The system is already attracting interest from the scent industry. As the professor excitedly showed off his gadgets, two executives from a large Japanese fragrance firm eagerly watched.
Eventually, an odour recorder could replace the perfume industry's "professional noses", people with an acute sense of smell whose job it is to oversee the consistency of batches of scents. The flavour industry is interested, too.
Other possible uses include online shopping where customers could sniff fresh goods before they buy, or helping doctors to diagnose patients from afar.
"Generating smells for virtual reality environments is a hot topic, too," said Prof Nakamoto.
Although not virtual reality, his team has recently exhibited a computer game that generates scents to match the onscreen action.
It is a relatively simple cooking game, where users wearing a mask add virtual ingredients to an onscreen frying pan to rustle up a Japanese curry.
As you add the butter and onions, realistic scents are pumped through the mask. In turn, garlic, meat and spice aromas complete the overall dish.
Professor Nakamoto admitted the demonstration is relatively frivolous but said the concept could be important for enhancing e-learning.
"When you present something together with smell then memory is enhanced," he said.
"For example, a student learning English may be presented with the word apple. If that is presented with the smell, too, it would be easier to remember."
Players of the cooking game add ingredients to a virtual frying pan
"Smellovision", tried and tested many times since the 1940s and recently demonstrated in a Japanese cinema accompanying Colin Farrell's film The New World, could also finally enter the mainstream.
Professor Nakamoto's team has augmented a sequence from the Japanese hit animation film Spirited Away.
A scene where the main character's parents gorge themselves on food before being transformed into pigs was enhanced with the smells of Chinese food, tofu and eventually the whiff of a pigsty.
A questionnaire circulated to viewers showed that they paid more attention to the scenes with smells.
"With this kind of technique we could also add smells to TV or DVDs."
At the moment, the kit is still very large and not the kind of thing that you would have in the corner of your lounge, but Professor Nakamoto is convinced it could be miniaturised.
And if that happens, it could bring a whole new dimension to television, particularly extended sumo bouts or the more fragrant aspects of some natural history shows.