MEMS-Based Power Generation from Human Walking Motion

基于MEMS的人类行走运动发电这项研究探索了在不使人负重的情况下从人类行走运动中产生大量能量的创新方法。这种发电的主要挑战是(1)与行走运动相关的极低振动频率，(2)非周期振动频谱，以及(3)由于低频率而固有的低水平振动能量。例如，如果悬架基于传统的质量-弹簧系统，则1赫兹的共振频率需要非常低的弹簧常数和/或非常大的质量，并且如果悬架是基于传统的质量-弹簧系统，则仅由于重力，弹簧就会位移25厘米。初始位移会使发电机的尺寸变得非常大，除非有某种机制来减小初始位移。因此，从人类行走运动中产生电力(负荷可以忽略不计)需要非常创新的方法。这项研究的成功成果将意味着一种分别小于1毫升和1克的发电机，可以从人类行走(而不是跑步)的运动中产生高达数十微瓦的能量。因此，这项研究将对可穿戴设备和植入式医疗设备产生重大影响，因为发电机将能够更换或补充电池。该研究还将对基于非固体弹簧、非共振悬浮、新型线圈设计和微制造等的高效电磁发电产生新的见解。研究旨在探索各种微电子机械系统(MEMS)方法，在不对发电机(总质量和体积分别为1克和1毫升)的佩戴者施加负载或影响的情况下，高效地利用与人类行走运动相关的振动能量来发电。具体研究的将是基于非固体弹簧(如磁弹簧、抗磁弹簧和液体弹簧)的非传统验证质量悬浮系统，这些弹簧可以很容易地在很低的频率下共振。还将探索一种基于磁流体轴承的非共振悬浮，它将悬浮磁体阵列，使其能够在非常小的摩擦下移动，以便从从亚赫兹到几赫兹的广泛频率范围内产生电力。此外，不仅将使用垂直磁通量平面内梯度，而且将使用水平磁通量平面内梯度，以便通过在两个相邻磁体之间的边界处利用快速变化的磁场，特别是在平行于平面的方向上的快速变化的磁场，来增加给定体积和/或质量的输出功率水平(因为具有交替的南北方向的磁体排列在平面表面上)。将探索各种微制造技术来制造具有非常大圈数的线圈阵列的堆叠板，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，并通过使用基金会的智力优势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.