TY - JOUR

T1 - Air gap optimization for output power and band width in out-of-plane vibration energy harvesters employing electrets

AU - Asanuma, H.

AU - Hara, M.

AU - Oguchi, H.

AU - Kuwano, H.

PY - 2015/9/24

Y1 - 2015/9/24

N2 - We investigated the dependence of output power, frequency band width, and resonance frequency on the initial air gap for electret-based out-of-plane vibration energy harvesters, both numerically and experimentally. In this investigation, the external acceleration and surface charge densities of the electret were held constant. The numerical investigation predicted the following results: (1) an optimum value exists in the initial air gap to maximize the output power; and (2) enhanced electrostatic forces with decreasing the initial air gap emphasize the soft spring effect, which widens the frequency band width and lowers the resonance frequency. The experimental results showed behaviour consistent with the numerical predictions. The maximum output power in experiment was 4.0 μW at the optimum initial air gap of 0.43 mm when the external acceleration and the frequency were 4.9 m s-2 and 102 Hz, respectively. With reducing the initial air gap to 0.28 mm, the frequency band width increased to 17 Hz, a 2.6-fold increase over the optimum initial air gap. The peak output power at the initial air gap of 0.28 mm was 2.7 μW, when the external acceleration and frequency were 4.9 m s-2 and 96 Hz, respectively.

AB - We investigated the dependence of output power, frequency band width, and resonance frequency on the initial air gap for electret-based out-of-plane vibration energy harvesters, both numerically and experimentally. In this investigation, the external acceleration and surface charge densities of the electret were held constant. The numerical investigation predicted the following results: (1) an optimum value exists in the initial air gap to maximize the output power; and (2) enhanced electrostatic forces with decreasing the initial air gap emphasize the soft spring effect, which widens the frequency band width and lowers the resonance frequency. The experimental results showed behaviour consistent with the numerical predictions. The maximum output power in experiment was 4.0 μW at the optimum initial air gap of 0.43 mm when the external acceleration and the frequency were 4.9 m s-2 and 102 Hz, respectively. With reducing the initial air gap to 0.28 mm, the frequency band width increased to 17 Hz, a 2.6-fold increase over the optimum initial air gap. The peak output power at the initial air gap of 0.28 mm was 2.7 μW, when the external acceleration and frequency were 4.9 m s-2 and 96 Hz, respectively.

KW - air gap

KW - electret

KW - soft spring

KW - stainless steel

KW - vibration energy harvester

KW - wide band

UR - http://www.scopus.com/inward/record.url?scp=84947594705&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84947594705&partnerID=8YFLogxK

U2 - 10.1088/0960-1317/25/10/104013

DO - 10.1088/0960-1317/25/10/104013

M3 - Article

AN - SCOPUS:84947594705

VL - 25

JO - Journal of Micromechanics and Microengineering

JF - Journal of Micromechanics and Microengineering

SN - 0960-1317

IS - 10

M1 - 104013

ER -