Energy harvesting involves collecting various forms of energy, including vibrations, heat and electromagnetic waves that are already present, either in an IoT device itself or the surrounding environment. The goal is to convert these energy forms into usable electrical energy, thereby creating self-powered systems that no longer require batteries. This is where piezoelectric, magnetostrictive and magnetoelectric materials come into play. Each of these materials are of particular interest in the field of energy harvesting due to their unique ability to produce electric or magnetic power on their own. Piezoelectric ceramics and polymers are materials that can generate electricity in response to surrounding vibrations and mechanical stress. These materials include lead zirconate titanate (PZT) and polyvinylidene fluoride (PVDF), both of which have been exploited for many useful energy applications. Magnetostrictive materials, on the other hand, include iron, nickel, cobalt and gallium. Each of these materials are ferromagnetic, meaning they are attracted to magnets and their magnetisation changes as a result of external load. When a wire is coiled around magnetostrictive devices, a current is induced, thus displaying their energy-harvesting potential. Magnetoelectric materials exhibit a coupling between their magnetic and electric properties. This means that when the materials are moved through an electric field, they become magnetised. Bismuth ferrite is an example of a multiferroic material that exhibits both ferromagnetism and ferroelectricity or spontaneous electric polarisation. Narita’s lab is currently working on fabricating different types of piezoelectric and magnetostrictive compounds that can effectively generate energy. More specifically, they wish to create devices that can harvest energy through vibrations and temperature. Currently, piezoelectric and magnetostrictive energy harvesters are restricted. ‘Piezoelectric harvesters are currently limited by their high impedance, which reduces the available current,’ doctoral student Zhenjun Yang explains, ‘whereas the development of magnetostrictive harvesters requires enhancement of magnet and coil qualities.’ Additionally, most piezoelectric and magnetostrictive materials are incredibly brittle, which greatly limits their ability to be applied on an industry level. With these imperfections, a lot of energy within these materials remains unused within IoT devices. By creating devices that are both effective in a variety of environments and low in cost, Narita and his team can replace expensive energy-generating materials and reach a broad range of industries that require IoT products.