In this age of advanced smartphones and wearable devices, the need of unlimited power has become a basic necessity. Most of the gadgets rely on some sort of power source in the form of batteries or power adapters. For example, smart watches have become very common these days and have a huge potential for implementation of energy harvesters. In near future it will be really desirable to have self-powered smart wearable devices which meet their energy needs by scavenging mechanical energy produced by physical activities. In order to solve the problem of fast battery depletion in modern smart devices, a lot of research has been carried out in the field of energy harvesters especially using thin film technologies and polymer nanofibers. Most interesting among them are the nanogenerators using polymers with piezoelectric properties like PVDF due to their low production cost and high conversion efficiency. Polymer-based nanofiber energy harvesters are not only relevant for wearable devices and smartphones but also for biomedical energy scavenging applications primarily due to their biocompatibility. Chapter 2 particularly deals with current scenario of different types of nanofiber-based energy harvesters. A comprehensive review related to current research work going on in the field of nanofiber-based energy harvesters is presented here.