Microdevices having a preferential axis of magnetization and uses thereof

A microdevice, which microdevice comprises:

• a) a magnetizable substance;
• b) a photorecognizable coding pattern,
• wherein said microdevice has a preferential axis of magnetization,and wherein an induced magnetization in its absolute magnitude along the preferential axis of the magnetization of said microdevice is at least 20% more than an induced magnetization of said microdevice along at least one other axis, wherein said microdevice has a thin rectangular shape with the preferential axis of the magnetization substantially in the direction of the length of the microdevice, and
• i) wherein said microdevice comprises at least two rectangular structures of said magnetizable substance separated by a non-magnetizable metal layer, and said microdevice has unequal number of said magnetizable substance rectangular structures on each side of said non-magnetizable metal layer along major axis of said microdevice;
• or
• ii) two rectangular structures of the magnetizable substance along the major axis of the microdevice and at least one of the rectangular structures has fingers on both ends, and
• c) a binding partner that is capable of binding to a moiety on a surface of the microdevice.