There are some devices that are in production. Here's a link that discusses minesweeping technology.

My personal favorite was the Scorpion, one of "Hobart's Funnies" during WWII. Basically, it used a bunch of heavy chains attached to a rotating drum mounted on the front of a tank. The chains flailed the ground and detonated land mines. These vehicles played an important role in the D-Day landings. The joint German-Israeli Keiler system uses this technology today.

No one device is likely to be effective against every type of land mine. There are some really twisted people designing these things and they've been busy making them harder to locate and deactivate. Still, the Keiler is claimed to be quite effective against most types of mines, a claim this report seems to refute.