HELSINKI (Reuters) - Finnish scientists have invented a device to make it harder to steal mobile phones and laptops by enabling them to detect changes in their owner's walking style and then freeze to prevent unauthorized use. The VTT Technical Research Center of Finland said the device, which is has patented but has yet to sell, could prevent millions of portable appliances being stolen every year. "A device is equipped with sensors that measure certain characteristics of the user's gait. When the device is used for the first time, these measurements are saved in its memory," VTT said in a statement. The gadget would monitor the user's walking style and check it against the saved information. If the values differ, the user would have to enter a password. "Compared with passwords and traditional bio-identification, the new method is simple: confirmation of identity takes place as a background process without any need for user's intervention," the researchers said.