Any particle with a target molecule on its surface will stick to the spin valve.

ECONOMIST: Labs on a chip

Others researchers use magnetism not only as a way of detecting the target, but also as a way of carrying it to the spin valve.

ECONOMIST: Labs on a chip

In either case, each spin valve reacts to only one sort of molecule, so the chips can search simultaneously for as many types of molecules as they have spin valves.

ECONOMIST: Labs on a chip

To search for a target molecule, then, all that would be needed would be to sprinkle a sample thought to contain it with magnetic nanoparticles coated with the appropriate antibody or DNA and then run it over a spin valve.

ECONOMIST: Labs on a chip

In a paper in the Journal of Immunological Methods, Wendy Dittmer of Philips claims to have achieved a 100, 000-fold increase in detection speed by hurrying magnetically tagged molecules of parathyroid hormone towards the spin valve with an electromagnet instead of allowing them to diffuse there.

ECONOMIST: Labs on a chip