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Pass the wasabi

By Margaret Harris



Bristol’s St Nicholas Market is an eclectic place, packed with hole-in-the-wall restaurants and shops selling everything from novelty T-shirts and herbal remedies to sheet music and sewing supplies. Today, however, it was even more eclectic than usual, since one of the customers at the curry house was Makoto Imai, the Japanese psychiatrist who won an Ig Nobel prize in 2011 for his role in inventing a wasabi-based smoke alarm.

Imai was accompanied by Ig Nobel organizer Marc Abrams, a friend of Physics World whom I met at a scientific conference back in 2009. They’re touring the UK right now as part of National Science and Engineering Week, putting on a show about the Ig prizes and other examples of science that – as Abrams explained to the slightly bemused Bristolian who shared our table at lunch – “first makes you laugh, and then makes you think”.

The wasabi smoke alarm is a good example. Wasabi is Japanese horseradish, otherwise known as that deceptively mild-looking green paste that comes with sushi. As anyone who has ever tasted it will know, a little bit of wasabi goes a very long way, and it turns out that a mere whiff of it can be enough to wake people from a deep sleep. In a creative leap worthy of Archimedes, Imai and his colleagues at Shiga University in Japan realized that this potent odour could make a very effective warning signal for people with deafness, who would not hear conventional sirens and might miss flashing lights if they were fast asleep. And so the wasabi smoke alarm was born.

From the outside, the alarm – which Imai obligingly got out of his bag to show me – is an unassuming grey box about as long as an A4 page and one-third as wide. Inside are the circuits needed to receive a signal from a modified ordinary smoke alarm, some batteries and a small but forbiddingly labelled aerosol can containing allyl isothiocyanate, the active ingredient in wasabi. The alarm has a radius of about 2.5 m, Imai told me, which makes it perfect for mounting above your bed. He also explained that, strictly speaking, it’s not an odour that wakes you up – it’s more of a sharp tickling sensation in the back of the throat that makes you cough.

Sadly I didn’t get a chance to try out the alarm at lunch – our fellow market-goers might have objected – and tonight’s Bristol Ig Nobel show featuring Imai is already sold out. However, I understand that Imai will be donating one of his devices to the Science Museum in London, and there are still tickets available for other UK Ig events later this week in Edinburgh and Dundee.

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