High efficiency and wide bandwidth are the main optimization directions for energy harvester. Based on flexoelectric theory, this paper presents a micro cantilever vibration energy harvester (VEH) with a broad bandwidth which achieved by collisions of two beams. The nanocrystalline graphene (NCG) is selected as base layer because its quality factor (Q factor) is highest compared with common materials, which means its energy loss in progress of power conversion is lowest and device has a high sensitivity to external excitation. Considering flexoelectric effect, based on Hamilton’s principle and Hertz contact force model, the electromechanical coupling equations are obtained. Numerical simulations are conducted. Output voltages of upper and lower beam are calculated respectively and the frequency response curve of the power density is obtained. It has been found that the maximum output voltage of flexoelectric energy harvester is almost 5 times that of piezoelectric energy harvester when the thickness of substrate layer is 400 nm. The effects of some parameters, such as resistance, gap distance between two beams, and tip mass, on the performance of harvester are studied. It indicates that the working bandwidth of the VEH has increased approximately fourfold, and the output power density is improved in some case due to collision of two beams, which has been verified by experiment. This work designs a novel efficient micro VEH and provides a theoretical basis for structure optimization.

高效和宽带宽是能量收集器的主要优化方向。基于柔电理论，本文提出了一种微宽悬臂振动能量采集器（VEH），其通过两个梁的碰撞实现了较宽的带宽。选择纳米晶石墨烯（NCG）作为基础层是因为其品质因数（Q与普通材料相比，它是最高的），这意味着其在功率转换过程中的能量损耗最低，并且器件对外部激励具有很高的灵敏度。在考虑了柔电效应的基础上，基于汉​​密尔顿原理和赫兹接触力模型，得到了机电耦合方程。进行数值模拟。分别计算上下光束的输出电压，得到功率密度的频率响应曲线。已经发现，当基底层的厚度为400nm时，柔性电能量收集器的最大输出电压几乎是压电能量收集器的最大输出电压的5倍。研究了一些参数（例如阻力，两根梁之间的间隙距离和尖端质量）对收割机性能的影响。这表明VEH的工作带宽增加了大约四倍，并且由于两束光的碰撞，在某些情况下输出功率密度有所提高，这已通过实验验证。这项工作设计了一种新型的高效微型VEH，并为结构优化提供了理论基础。