The popular Iron Man movie franchise and comic features a suit of body armor that could make any engineer green with envy. The Iron Man suit, a work of science fiction, seems to be a feat of futuristic engineering not yet possible today. Or is it? Scientists are working on an impenetrable suit of body armor consisting of iron particles and a carrier liquid. This liquid body armor is possible because it contains magnetorheological (MR) fluids.

MR fluid is a smart liquid capable of solidifying when passing through a magnetic field. MR fluid differs from ferrofluid, which contains ferromagnetic particles with a surfactant to inhibit clumping because it thickens when magnetized. MR fluid would make effective body armor because it’s flexible and the hardening process is extremely fast.

How It Works

The carrier oil contains magnetic particles usually consisting of iron. The magnetic particles make the liquid dense but retain a fluid viscosity. This image by Will Becker demonstrates the MR fluid when not within a magnetic field:

magnetorheological fluid off state liquid body armor magnet

When a magnetic field is applied, the iron particles align along the magnetic flux lines as shown below in this image also by Will Becker:

magnetorheological fluid liquid body armor on state magnetic flux

MR fluid is already used in various practical ways today such as for damping and dissipative devices. You can experiment with your own MR fluid with this DIY tutorial:



All you have to do is mix the iron filings with the vegetable oil. You should be able to mix it around although it’s thicker than water. Your DIY MR fluid should have a consistency reminiscent of greasy mud. Now, the cool part is when you move the magnet near your MR mud. It will thicken and form linear patterns in response to the magnetic field. A similar phenomenon can be observed between iron filings and a magnet without the oil. Your MR mud will solidify under the influence of a magnetic field.

While this experiment with MR fluid is informative and fun, the simple mixture won’t make you a real-life Iron Man. The technology is still unable to stop bullets but maybe sometime in the near future you'll get to see a liquid version of the Iron Man suit.

Image by INVENTUS Engineering GmbH