Wrinkling And Energy Harvesting Of Dielectric Film Based On Flexoelectricity

Microelectronic devices are often used as sensing nodes to form a large data acquisition network and undertake information monitoring and data feedback.Stable energy supply to these sensing nodes is a challenging technical problem.In order to solve this problem,the energy harvesting technology,which can directly obtain electric energy from the environment of electronic devices,has received more and more attention.The traditional energy harvester is mostly based on piezoelectricity,but piezoelectricity is greatly reduced as the material scale drops to the micron scale.Therefore,the energy harvesting technology based on flexoelectricity becomes a new exploration direction.In this paper,based on the Euler-Bernoulli beam theory,the theoretical analysis and numerical calculation of the wrinkling behavior of the nanofilm/substrate structure under the external electric field are carried out.The mechanism of flexoelectricity on the electrical coupling characteristics of the structure is studied,and the effects of pre-strain,voltage,thickness ratio and other parameters on wrinkling occurrence and deformation are discussed.Then,a new model of flexoelectric energy harvester based on the controllable wrinkling structure is proposed.At the same time,the electrode regrouping method is used to further improve the energy conversion efficiency of the flexoelectric energy harvester.Through the parameters study,the energy harvesting potential of flexoelectric energy harvester is explored.Finally,the energy efficiency of the current flexoelectric energy harvester is comprehensively compared with the results of the literature,which highlights its performance.The results show that for the nanofilm/substrate structure,flexoelectricity plays a slight role on promoting its wrinkling occurrence,but tends to reduce the wrinkling amplitude,especially below the small scale.The energy harvesting efficiency of the flexoelectric energy harvester also has a strong scale-dependent effect.When the scale is further reduced,its energy harvesting efficiency will be significantly enhanced.For the flexoelectric energy harvester,the electrode regrouping method helps to improve its energy harvesting efficiency,and a smaller resistor will effectively increase its output power,but a larger loading frequency is required to excite the maximum output power.The power density of the current flexoelectric energy harvester based on wrinkling type is at least one order of magnitude higher than that of other flexoelectric energy harvester based on vibrating type.When the size of the structure is reduced to less than 0.1μm,the power density of the current flexoelectric energy harvester can be up to10~4 W m~3,which is 2 to 5 orders of magnitude higher than that of most low frequency vibrating energy harvesters.