Contactless sensing device

A contactless sensing device for sensing an information of a moving tested object, the device comprising:

• a magnetic stripe, having alternatively and equally arranged plurality of N-pole blocks and S-pole blocks;
• a detector, including a fixed magnetic layer with a fixed magnetic direction, a free magnetic layer with a changeable magnetic direction influenced by an external magnetic field, an insulating layer separated the fixed magnetic layer from the free magnetic layer, two signal lines electrically connected to the fixed magnetic layer and the free magnetic layer respectively, and a power supply electrically connected to the signal lines;
• and
• a processor, electrically connected to the signal lines;
• wherein the magnetic stripe is fixed on the moving tested object, the detector is arranged at a proper position, while the moving tested object is moving to make the magnetic stripe pass through the detector, the changeable magnetic direction of the free magnetic layer is influenced by the N-pole blocks and the S-pole blocks of the magnetic stripe to result in parallel or anti-parallel to the magnetic direction of the fixed magnetic layer, and the induced changes of the magnetoresistance further result in the changes of the output signals to the processor, and then the information of the moving tested object is sensed and calculated from the processor.