Electrets in Engineering provides a comprehensive overview of the structure and properties of electret materials used in engineering, medicine, and biotechnology. Characterized by their ability to generate a constant electric field, electrets have traditionally been used as a method of electronic focussing in applications such as gas filters and microphones. However, in recent years it has been demonstrated that they have a much wider sphere of application from controlling lubrication in machine parts to regulating drug diffusion. This book begins by introducing the concept and the underlying physics of electrets before going on to discuss the many applications. Starting with a discussion of traditional applications, such as acoustic transducers and filters, it then moves on to more novel uses. Their use as an anticorrosion and polymer coating technique is examined as well as their role in the lubrication of friction joints. Biological and medical applications are also covered before the final chapter looks into the economic and ecological aspects of these materials. Electrets in Engineering will be of interest to all material scientists and engineers with an interest in this developing field, from students needing a general introduction, to practising engineers and scientists requiring an insight into exactly how electrets relate to specific applications.