Impact-activated programming of electro-mechanical resonators through ferroelectret nanogenerator (FENG) and vanadium dioxide
Impact-activated programming of electro-mechanical resonators through ferroelectret nanogenerator (FENG) and vanadium dioxide
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DOI：
10.1016/j.nanoen.2017.10.066
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发表时间：
2018-01-01
期刊：
影响因子：
17.6
通讯作者：
Sepulveda, Nelson
中科院分区：
文献类型：
--
作者：
Cao, Yunqi;Li, Wei;Sepulveda, Nelson
最近推出了铁电体纳米发电机 (FENG) 设备，作为能量收集和麦克风/扬声器应用的有前途的灵活设备。另一方面，二氧化钒 (VO2) 薄膜已被证明能够实现微型机电结构的大频率可调性，这些结构通常集成在收发器和通信系统中。在这项工作中，我们集成了这两种技术，展示了一个系统，其中由 FENG 提供的电脉冲可用于调整基于 VO2 的微机电结构的谐振频率。此外，由于 VO2 的迟滞行为，所施加的脉冲还可对调谐频率进行编程，从而允许在单次施加的直流偏压下在器件中实现不同的频率状态。研究发现，频率状态的调谐是由所提供的能量决定的，并且对于较大、较短的脉冲，即使脉冲的持续时间短于系统的热时间常数，编程也更加有效。我们探索两种不同的机械结构：桥梁和悬臂。桥结构的调谐范围更宽 (22%)，这是由于这种配置的应力频率敏感性更大。调谐/编程动作使用收集的机械能，该机械能可能来自用户。讨论了所开发的系统作为加速度计或冲击传感器来监测接触运动中脑损伤的潜在用途。
Ferroelectret Nanogenerators (FENG) devices were introduced recently as promising flexible devices for energy harvesting and microphone/loud-speaker applications. Vanadium dioxide (VO2) thin films, on the other hand, have been demonstrated to enable large frequency tunability of miniaturized electro-mechanical structures, which are commonly integrated in transceiver and communication systems. In this work, we integrate these two technologies, to show a system where an electric pulse, supplied by the FENG can be used to tune the resonant frequency of VO2-based micro-electro-mechanical structures. Furthermore, due to the VO2's hysteretic behavior, the applied pulse also programs the tuned frequency, allowing for different frequency states in the device for a single applied DC bias. It is found that the tuning of the frequency states is determined by the supplied energy, and the programming is more efficient for larger, shorter pulses -even if the duration of the pulse is shorter than the system's thermal time constant. We explore two different mechanical structures, bridge and cantilever. A wider tuning range is found for the bridge structure (22%), which is due to the larger frequency sensitivity with stress for this configuration. The tuning/programming action uses harvested mechanical energy, which could come from the user. The potential use of the developed system as an accelerometer or impact sensor for monitoring brain injuries in contact-sports is discussed.