Bulletproof vests stop bullets, but not sweat. That can cause overheating for anyone wearing the vests. But now a new kind of vest, which has cooling pads and fans, could reduce dangerous overheating and make bulletproof vests more comfortable, especially in hot weather. Soldiers and police officers could see improved performance as a result.
The vest was designed by Empa, a Swiss research institute. It has an integrated cooling system based on a technology called Coolpad, originally designed for use in cooling garments used in medicine. The pads built into the vest are filled with water. The water evaporates through a membrane, which cools the person in the vest the same way sweat does. To get additional cooling, a miniature fan blows air through a fabric spacer behind the pad.
A big challenge was that the fabric spacer needed both to be able to handle pressure and to be flexible and soft. It also had to allow air to flow. Another concern was the fans — there were no fans small enough to fit inside the vest. On top of that the water in the cooling pads leaked.
The fabric spacer was designed in partnership with a Swiss textile manufacturer. The engineers at Empa ended up designing the fans themselves, as well as the control electronics and the batteries. Fixing the water-filled pads required welding them with diode lasers.
The vest can be resupplied with water and fresh fan units (the fans and rechargeable batteries are single units). The water is refilled with a quick-release valve. The vest can provide cooling for three to four hours.
The Zurich City police force tested the vest during several warm summer days and declared it a success. The first of them will be made by Unico Swiss Tex GmbH. But bulletproof vests aren't the only use of this technology;it could also be used for protective suits worn over normal clothing, camouflage suits and even for small backpacks, and there is already development work being done.