Electret Filters for High-Efficiency and High-Flow Air Cleaning

A new type of air filter in which the dust particles are captured very effectively by electrostatic forces is presented. This is accomplished by making the filter from polymer fibers that carry a permanent positive and negative charge. A method is outlined for producing such filters on a large scale and results are given of tests in which the filters are challenged with various aerosols. The advantage of the new filters is that they combine a high capturing efficiency with a low resistance to air flow. Among the numerous applications, personal protective face masks for people working in dusty environments are especially valuable.