Apparatus for agitation separation of magnetic particles

An electronic device for generating a plurality of magnetic field gradients in differing orientations about an active region, such that only one of said magnetic field gradients is generated at any one time and different ones of the magnetic field gradients are alternately generated at differing times, comprising:

• a) a chassis comprising electrical ground, and containing a point above which the active region is located;
• b) a first electromagnet, a second electromagnet and a third electromagnet, each of said electromagnets having a base and two electrical leads, and mounted to said chassis, the bases of each of the electromagnets disposed about said point and essentially coplanar with a section through said active region such that the base of said first electromagnet is placed opposite the base of the second electromagnet on the chassis, and the base of the third electromagnet is placed between said bases of said first and said second electromagnets;
• c) a source of current having a positive lead and a negative lead, mounted to said chassis, said negative lead electrically connected to said chassis and comprising electrical ground;
• d) an electronic circuit mounted to said chassis, said electronic circuit being selectively, electronically connected and disconnected to the positive lead of said source of current and to ground, and further electrically connected in parallel to the leads of two of said electromagnets, said electronic circuit providing a means for alternately distributing said current to one or another of said two electromagnets at differing times;
• e) means interposed between said positive lead of said source of current and said electronic circuit for selectively connecting and disconnecting said electronic circuit to said source of current;
• and
• f) means for selectively connecting said third electromagnet to said source of current, said selectively connecting means connecting said third electromagnet to said source of current only when said electronic circuit is disconnected from said source of current;
• whereby said first and said second electromagnets are capable of effecting agitation of magnetic particles within a diamagnetic container placed in said active region and said third electromagnet is capable of immobilizing the magnetic particles.