A nonlinear interface integrated lever mechanism for piezoelectric footstep energy harvesting

Journal Article · 02 August 2018 · Applied Physics Letters

DOI: https://doi.org/10.1063/1.5041259 · OSTI ID:1540236

Hua, Rui ^[1]; Liu, Haili ^[2]; Yang, Haocheng ^[2]; Wang, Ya  ^[3]; Ferrante, Jack ^[4]

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1. Texas A&M Univ., College State, TX (United States). Dept. of Mechanical Engineering; DOE/OSTI
2. Stony Brook Univ., NY (United States). Dept. of Mechanical Engineering
3. Texas A&M Univ., College State, TX (United States). Dept. of Mechanical Engineering
4. Duke Univ., Durham, NC (United States). Dept. of Mechanical Engineering

Harnessing footstep energy allows for a unique method of power generation from a largely untapped resource, with applications such as instantly charging mobile and wearable electronic devices. This letter presents an easily integrated heel charger to efficiently convert kinematic walking energy into electricity. The heel charger uses a multilayered levered piezoelectric (L-Pie) mechanism associated with a nonlinear mechanical-synchronized switching on inductor circuit (M-SSHI) interface. It tactfully switches on when the foot contacts the ground, and switches off when the foot is lifted. This design takes full advantage of the user's weight, and amplifies footstep displacement by utilizing the lever mechanism to gain maximum deformation of multilayer piezoelectric patches. The experimental results show that the fabricated two-level multilayer L-pie has a top performance of 13.60 mW of AC RMS, a mechanical to AC power conversion efficiency of 7.87%, and a DC RMS power of 6.13 mW, an AC to DC power conversion efficiency of 45.07%, under a harmonic excitation of 2.3 Hz (mimicking fast walking speed: 6.2 km/h for men, 5.55 km/h for women). With an optimal load of 210 kΩ, the two-level L-pie using the M-SSHI has an improvement of 206.45% in DC RMS power compared to a standard 4-diode bridge energy harvesting circuit. Finally, the L-pie design works more efficiently under large force excitation, even with small displacement, which makes this technology optimal for footstep energy harvesting.

• Research Organization: State Univ. of New York (SUNY), Albany, NY (United States)
• Sponsoring Organization: USDOE Advanced Research Projects Agency - Energy (ARPA-E)
• Grant/Contract Number: AR0000531
• OSTI ID: 1540236
• Alternate ID(s): OSTI ID: 1462790
• Journal Information: Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 5 Vol. 113; ISSN 0003-6951
• Publisher: American Institute of Physics (AIP)Copyright Statement
• Country of Publication: United States
• Language: English