MEMS-Based Power Generation from Human Walking Motion

基于MEMS技术的人体行走发电 本研究探索了创新的方法，从人类的步行运动产生大量的权力，而不加载的人。这种发电的主要挑战是（1）与行走运动相关联的极低振动频率，（2）非周期性振动频谱，以及（3）由于低频率而固有地低水平的振动能量。例如，如果悬架基于传统的质量-弹簧系统，则1Hz的谐振频率需要非常低的弹簧常数和/或非常大的质量，并且弹簧仅由于重力而移位25 cm。初始位移将使发电机的尺寸非常大，除非有某种机制来减小初始位移。因此，从人的行走运动发电（具有可忽略的负载）需要非常创新的方法。这项研究的成功结果将意味着一个发电机更小和更轻，分别小于1毫升和1克，可以产生高达几十微瓦的人类步行（不跑步）运动。因此，这项研究将极大地影响可穿戴设备和植入式医疗设备，因为发电机将能够取代或补充电池。该研究还将为基于非实心弹簧、非共振悬浮、新型线圈设计和微加工等的高效电磁发电提供新的见解。 该研究旨在探索各种微机电系统（MEMS）方法，以有效地从与人类行走运动相关的振动能量中产生电力，而不会对发电机的佩戴者产生负载或影响（总质量和体积分别为1克和1 cc）。具体研究的将是基于非实心弹簧（如磁性弹簧、抗磁性弹簧和液体弹簧）的非常规检测质量悬挂系统，这些非实心弹簧可以很容易地在非常低的频率下共振。还将探索一种基于铁磁流体轴承的非共振悬浮系统，该系统悬挂磁体阵列并允许其以非常小的摩擦力移动，以便从亚赫兹到几赫兹的广泛频率范围内发电。此外，将不仅使用垂直磁通量平面内梯度，而且使用水平磁通量平面内梯度，以便对于给定体积和/或质量增加输出功率水平（因为具有交替的南北取向的磁体阵列布置在平面上）通过利用快速变化的磁场，特别是在平行于平面的方向上，在两个相邻的磁铁之间的边界处。此外，还将探索各种微细加工技术，以制造匝数非常多的线圈阵列的层叠板，并以非常低的成本批量生产发电机。该奖项反映了NSF的法定使命，通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

MEMS-Based Power Generation from Human's Walking Motion This research explores innovative approaches for generating substantial power from human's walking motion without loading the person. The major challenges in such a power generation are (1) extremely low vibrational frequency associated with walking motion, (2) non-periodic vibration spectrum, and (3) inherently low level of vibration energy due to the low frequency. For example, 1 Hz resonant frequency requires a very low spring constant and/or a very large mass, and the spring is displaced by 25 cm due to gravity alone, if the suspension is based on a conventional mass-spring system. The initial displacement would make the power-generator size very large, unless there is some mechanism to reduce the initial displacement. Thus, power generation (with negligible load) from human's walking motion requires very innovative approaches. The successful outcome of the research will mean a power generator smaller and lighter than 1 cc and 1 gram, respectively, that can generate up to tens of microWatts from human's walking (not running) motion. Thus, the research will greatly impact wearable devices and implantable medical devices, as the power generator will be able to replace or supplement battery. The research will also produce new insights into efficient electromagnetic power generation based on non-solid springs, non-resonant suspension, novel coil design and microfabrication, etc. The research is to explore various Microelectromechanical Systems (MEMS) approaches to efficiently generate power from vibration energy associated with human's walking motion without loading or affecting the wearer of the power generator (with a total mass and volume of 1 gram and 1 cc, respectively). Specifically studied will be non-conventional proof-mass suspension systems based on non-solid springs (such as magnetic spring, diamagnetic spring and liquid spring) that can easily be made to resonate at a very low frequency. Also explored will be a non-resonant suspension based on ferrofluid bearing that suspends a magnet array and allows it to move with very little friction, in order to generate power from a broad range of frequencies spread from sub-Hz to several Hz. Furthermore, not only the vertical magnetic-flux in-plane gradient, but also the horizontal magnetic-flux in-plane gradient, will be used in order to increase to the output power level for a given volume and/or mass (as an array of magnets with alternating north and south orientation is arranged on a planar surface) through exploiting the rapidly changing magnetic field, particularly in the direction parallel to the planar surface, at the boundaries between two abutting magnets. And various microfabrication techniques will be explored to fabricate stacked plates of coil arrays with a very large number of turns and also to mass-produce the power generator at a very low cost.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.