Smart suits

By Harvey Black WORKING in hazardous environments could be made a lot safer by building an electrically conductive polymer into protective clothing. If the clothing is accidentally torn, the polymer closes a circuit, which immediately activates an alarm. The system, which has been patented by a team from the Los Alamos National Laboratory in New Mexico, has been built into material used for protective clothing designed to shield against radiation, toxic chemicals or bio-hazards. Knowing that they have been exposed to a hazard quickly will be a major improvement for some workers. At present, tears that leave the wearer exposed to the hazard may not be discovered for some time after they have occurred. Some existing puncture detection systems either do not work in real time, which means that they are only checked before protective clothing is donned. Others only work when pierced by electrically conductive materials, such as metal tools. The Los Alamos system, however, works when nonconductors such as wood puncture the clothing. This gives it broader use, according to Robb Hermes, one of its developers at Los Alamos. The system is simplicity itself: a gooey, conducting material is made by dissolving polyvinylalcohol and table salt (sodium chloride) in glycerol. Two layers of the conducting polymer, each with an embedded electrode, are separated by a nonconducting polymer. Two further layers of nonconducting polymer are then added to the other sides of the conducting layers. When there is a rip or puncture, the gooey conducting polymer layers are forced through the insulating layer between them, closing a circuit. This could be used to trigger a light emitting diode or audio alarm in the wearer’s face mask. Previous fabric warning systems used layers of thin metal foil separated by a nonconductor. These systems only worked when they were pierced by a conductor. The gooey polymer ensures that any tear will be registered. “I wanted to make it as simple as possible so businesses would adopt it,” says Hermes. Details of the wearer’s actual warning mechanism—sound or light-emitting diode—have yet to be decided. The polymer was originally developed for gloves built into the enclosed glove boxes used by workers at Los Alamos to manipulate radioactive materials. The gloves are replaced at regular intervals, but are not routinely tested, according to Los Alamos spokesman James Danneskiold. So if a glove is damaged, radioactive contamination is only detected after the exposure has occurred, sometimes many hours later. With the new system,
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