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.

Project Start
Project End
Budget Start
2019-07-01
Budget End
2022-06-30
Support Year
Fiscal Year
2019
Total Cost
$385,218
Indirect Cost
Name
University of Southern California
Department
Type
DUNS #
City
Los Angeles
State
CA
Country
United States
Zip Code
90089