Anti Depression Guide

Paint-based graffiti can usually be removed relatively easily from buildings, bus shelters and other street furniture. But graffiti that is scratched into surfaces such as Perspex is much more difficult to cope with and usually requires the entire surface to be replaced at great cost.

So Seng Chu Tan and colleagues at Curtin University of Technology in Perth, Australia, have developed a device that can hear when graffiti is being carved into surfaces.

A set of microphones attached to the surface is connected to a computer program that has been trained to distinguish background noise from the tell-tale signature of graffiti scratches.

When the computer picks up signs of vandalism in action, it triggers an alarm to scare off the perpetrators and call the authorities to investigate.

Read the full graffiti detector patent application.

Justin Mullins, New Scientist consultant

Photo: orangeacid

There is a continual battle between counterfeiters and banknote manufacturers. But Stuart Eaton and colleagues at UK military research company Qinetiq think they have designed the only technology that makes it possible for anyone to spot a fake by touch alone.

Most anti-counterfeiting techniques use visual cues such as watermarks or holograms, or machine-readable features like markings that only become visible under ultraviolet light.
Qinetiq's idea is to use spots of magnetic inks on a document such as a banknote, with alternating polarity.

To check a note's authenticity, you simply fold the note and rub it to feel the alternate attraction and repulsion as the inks move past each other.

The sensation would make a smooth piece of paper feel rippled, say the group, who think the technology could work on anything from passports to legal letters. Whether the idea would make notes difficult to stack or peel apart, we can only guess.

A touch-based system would have advantages in places where lighting is poor such as pubs and clubs, as well as being a useful aid to the visually impaired.

The public could be educated to learn how to recognise the particular pattern, says the patent, but no mention is made of how easy or difficult it would be for fraudsters to copy the design.

Read the full magnetic banknotes patent application.

Justin Mullins, New Scientist consultant