This paper presents a novel piezoelectric vibration energy harvester (PVEH) in which a high-frequency generating beam (HFGB) is driven by an array of low-frequency driving beams (LFDBs) using ropes. Two mechanisms based on frequency upconversion and multimodal harvesting work together to broaden the frequency bandwidth of the proposed vibration energy harvester (VEH). The experimental results show that the output power of generating beam (GB) remains unchanged with the increasing number of driving beams (DBs), compared with the traditional arrays of beams vibration energy harvester (AB-VEH), and the output power and bandwidth behavior can be adjusted by parameters such as acceleration, rope margin, and stiffness of LFDBs, which shows the potential to achieve unlimited wideband vibration energy-harvesting for a variable environment.

Though numerous piezoelectric vibration energy harvesters (PVEHs) have been designed and investigated to provide power supply for wireless sensors or wearable devices, it remains a challenge for traditional PVEHs to work effectively in an environment of low frequency, low acceleration and multidirectional vibrations. This work presents a PVEH using a low-frequency energy-capturing resonant system formed by a rolling ball in a hemispherical shell and driven by a rope. Due to the symmetry of the sphere, the ball can be excited at multiple directions in 3D space, and the piezoelectric beam can be pulled by the ball through a rope in multiple directions. Thus, the efficient multidirectional energy harvesting under low frequency (< 10 Hz) and ultralow intensity (< 0.1 g) vibrations could be realized. A mass-spring-damper equivalent model was built to understand the operation mechanism of the proposed PVEH. The results show that the proposed PVEH has a potential to collect energy in any direction in 3D space, and could achieve a good angle bandwidth with 360° for φ and 240° for β under the excitation of a = 0.04 g, f = 6.8 Hz with the acceleration defined in the spherical coordinate system. The developed PVEH can generate 6.5 μW under a low-intensity excitation (0.03 g), and the normalized power density can reach 22.63 μW/(cm3g2Hz). Moreover, the minimum start-up acceleration analysis of the proposed PVEH indicates that the PVEH can capture multidirectional energy from vibrations as low as 0.01 g. In addition, both simulation and experimental study on rope redundancy and ball mass show that they can be used to adjust the device performance easily without structure re-fabrication. Overall, this study demonstrates a new mechanism that could effectively harvest low frequency, ultralow intensity and multidirectional vibration

The Fast-Tool-Servo (FTS) is widely used for micro-structure manufacturing especially for micro optical lens. The working principle of FTS presented by Qiang Liu et.al is that, a voice coil motor and a piezoelectric（PZT） actuator are used as the driving elements, and two flexure hinges are developed as the guide mechanisms. However, vertical displacement jump happens when the flexure hinges are driven by a voice coil motor or a piezoelectric actuator. In this paper, a new amplified structure is presented, allowing the horizontal motion while reducing the vertical displacement jump. The working principle is that, the piezoelectric actuator is applied to a beam which has two flexure hinges, one is linked to the frame, and the other is linked to a tool holder which is situated through two parallel membranes. When the piezoelectric actuator deforms, the beam will rotate around the frame, while the displacement is amplified at the other end, causing the tool holder’s motion and the membranes are forced to bend, while the vertical motion is restrained by the membranes. As a result, the presented membrane based flexure structure is able to amplify the motion of the piezoelectric actuator. In addition, the vibration frequency of the membrane is easy to be adjusted by the preloaded force. It is important to know when the FTS is working at different frequency. The performance of the presented structure is analyzed by structural dynamics coupled with piezoelectric, and the parameters of the structure are optimized to remain linear relation between the tool holder and the piezoelectric actuator, while the vertical displacement jump is much smaller than the structure presented in reference.