Energy Harvesting is the process of converting into electricity the energy available from otherwise untapped sources, such as environmental vibrations or modest temperature gradients. If not harvested, this energy is simply wasted.
Energy harvesting is seen as an enabling technology for the Internet of Things (IoT), the interconnected future we are developing. Traditionally, vibrational energy harvesters are made of piezoelectric ceramics, notably PZT. But PZT is dense, brittle and contains noxious lead.
A novel alternative is offered by electromechanically active polymers. Among these, cellular polypropylene (PP) was found to exhibit a pseudo-piezoelectric behaviour when functionalised in a corona discharge. The light weight and mechanical flexibility of cellular PP is particularly advantageous for wearable energy harvesters.