Alarming news for shoplifters. A new way of unobtrusively tagging clothes will make it harder for them to sneak past the alarms at the door.
The device, from Sensormatic of Florida, uses a polymer strip with small dimples pressed into it (WO 03/012757). Tiny metallic discs are placed inside the dimples and sealed in with a plastic coating. An iron oxide ink is printed on top, and because it is magnetised, the discs inside are attracted to it.
As the strip passes through a 58-kilohertz radio signal at the shop door, the radio waves interfere with the magnetic field…
