Boost the voltage of a magnetoelastic generator via tuning the magnetic induction layer resistance

Using the giant magnetoelastic effect in the soft systems for ambient energy harvesting, namely, the magne-toelastic generator (MEG), is challenged by its relatively low voltage output. A conventional transformer could be employed to solve the problem by increasing the voltage at the expense of current; however, it holds a bulky and rigid configuration with considerable energy loss. Here, we developed the resistance-controllable magnetic in-duction (MI) layer with multi-walled carbon nanotubes (MWCNT) as an inner transformer to manipulate the electrical output of an MEG. With high electrical conductivity, flexibility, and mechanical strength, the resistance of the MWCNT-based MI layer can be designed by thickness, width, length, and turns of the coils, contributing to a power-transforming effect. As the resistances increased, the open-circuit voltage increased, while the short-circuit current showed a reversed trend. With a power density of 0.23 mV cm_2, the power-transforming MEG can charge a commercial capacitor at a rate of 0.63 mV s_ 1 with intrinsic waterproofness. This work introduces a compelling approach to boost the voltage output of the MEG via internally engineering the resistance of the MI layer.