Patent ID: 7985599

Claim:
A method of manipulating magnetic particles, which method comprises: providing a fluid having a plurality of magnetic particles dispersed therein; providing an array of spin valve magnetic traps, each of which comprises discrete substantially coplanar layers of material that, when temporarily subjected to a magnetic field of sufficient strength to change the magnetization state of the spin valve trap to an on state, produces a local magnetic field that is capable of attracting and indefinitely retaining magnetic particles proximate the spin valve magnetic traps; bringing the fluid having the magnetic particles dispersed therein proximate the array of spin valve magnetic traps; and temporarily subjecting each spin valve magnetic trap to the magnetic field so as to selectively switch between the on state, in which the local magnetic fields are produced and the magnetic particles are magnetically attracted and retained proximate the spin valve magnetic traps, and an off state, in which no local magnetic fields are produced and the magnetic particles are not attracted or retained proximate the spin valve magnetic traps, and wherein, in the on state, the local magnetic fields persist after the temporary magnetic field is discontinued.