12/12/2003: 
Technologica
Instant Armor
from ScienCentral News
Component of Armor before and after exposure to a magnetic field.
On the battlefield of the future, soldiers could be wearing uniforms that turn from soft, comfortable fabric to light, flexible, durable armor with a flip of a switch.
At Massachusetts Institute of Technology (MIT), the Institute for Soldier Nanotechnologies is dedicated to using nanoscale science's potential to produce a protective uniform for the U.S. Army. One research team headed by professor of mechanical engineering Gareth McKinley starts with an oily fluid full of very tiny iron particles, and a magnet.
"What we're working with is a class of fluids called magnetorheological fluids," says McKinley. "These are liquids that change their properties when we apply a magnetic field to them. They are made up of very, very small iron particles, much smaller than individual red blood cells," which the researchers then mix into a silicon oil, or even corn syrup, so they don't rust. The oil or syrup also makes the solution mayonnaise-thick, with just enough stiffness to prevent it from running.
When a magnetic field is applied to this solution, the tiny iron particles align with the magnetic field, and stack up on top of each other. As they do so, the fluid turns into a peanut butter-like substance that feels very hard. When the magnet is removed, the solid instantly reverts to liquid. The change happens incredibly quickly-"in about 20 thousandths of a second."
"Instant armor" is definitely not combat-ready yet. "We've got five to ten years of research before we can make this material truly bullet-resistant,"
