Latchable or lockable device

A lockable or latchable device, comprising:

• first and second members proximate to each other, at least one of said first and second members being movable with respect to the other;
• a magnetorheological fluid disposed in the device such that the fluid is in simultaneous contact with at least a portion of each of the first and second members when the first and second members are in a position for locking or latching;
• a permanent magnet disposed in the device such that magnetic flux from the permanent magnet inhibits shear of the magnetorheological fluid when the first and second members are in the locked or latched position, thereby preventing movement of the first and second members with respect to each other;
• and
• an electromagnet disposed in the device such that magnetic flux from the electromagnet, when activated, disrupts the magnetic flux of the permanent magnet when the first and second members are in the locked or latched position, thereby allowing movement of the first and second members with respect to each other while the electromagnet is activated;
• wherein portions of the first and second members are in simultaneous contact with the magnetorheological fluid in a slidable engagement with the magnetorheological fluid.