Optimization and realization of a space limited sens-PEH for smart floor applications

IoT and smart home applications demand for simultaneous sensing and energy independence. Here, a screen printable P(VDF-TrFE) cantilever based smart floor design, capable of sensing (sens) and acting as a piezoelectric energy harvester (PEH) is introduced. In a height of only 1 mm, which is well-suited for indoor floor applications, a sens-PEH cantilever optimization is performed by finite element method (FEM) simulations and experimentally validated; bending cantilevers perform much better compared to normal compressions modes with apparent sensitivities to be as high as 98 nC/N for 3.6 mm long cantilevers. This is more than three orders of magnitude larger compared to conventional flat P(VDF-TrFE) film sensors. When energy harvesting is of interest, the simulations show that short cantilevers provide the most energy. Using multilayered screen-printed devices and an active area of 8 cm2, such harvesters provide up to 18.4 µJ of step energy in the experiment, from which 6 µJ is storable in a capacitor. From the combined FEM and experimental results, the optimum sens-PEH geometry, either for sensing or harvesting, can be chosen and implemented in respective smart floor applications.