Improvement of vibration energy harvesters mechanical Q-factor through high density proof mass integration

[摘要] This paper reports on improvement of the mechanical Q-factor of resonant energy harvesters at ambient pressure via the use of tungsten proof masses by evaluating the impact of the mass size and density on the squeeze film damping. To this end, a simplified model is first proposed to evaluate cantilever beams deflection and the resulting fluid pressure build up between the mass and a near surface. The model, which accounts for simultaneous transverse and rotational motion of very long tip masses as well as for 2D fluid flow in the gap, is used to extract a scaling law for the device fluidic Q-factor Qf. This law states that Qfcan be improved by either increasing the linear mass density of the tip mass or by reducing the side lengths compared to the gap height. The first approach is validated experimentally by adding a tungsten proof mass on a silicon based device and observing an improvement of the Q-factor by 103%, going from 430 to 871, while the resonance frequency drops from 457 to 127 Hz. In terms of fluidic Q-factor, this represents an increase from 562 to 1673. These results successfully demonstrate the benefits of integrating a tungsten mass to reduce the fluid losses while potentially reducing the device footprint.

[发布机构] Institut Interdisciplinaire d'Innovation Technologique (3IT), 3IT.nano, Université de Sherbrooke, Sherbrooke; QC; J1K 0A5, Canada^1;Laboratoire de Nanotechnologie et Nanosystème (LN2), CNRS UMI-3463, Université de Sherbrooke, Sherbrooke; QC; J1K 0A5, Canada^2

[效力级别] 能源学

[关键词] Ambient pressures;Fluid pressures;Linear mass density;Resonance frequencies;Rotational motion;Silicon-based devices;Squeeze-film damping;Vibration energy harvesters