A Frequency Up-Converted Hybrid Energy Harvester Using Transverse Impact-Driven Piezoelectric Bimorph for Human-Limb Motion

Energy harvesting from human-body-induced motion is mostly challenging due to the low-frequency, high-amplitude nature of the motion, which makes the use of conventional cantilevered spring-mass oscillators unrealizable. Frequency up-conversion by mechanical impact is an effective way to overcome the challenge. However, direct impact on the transducer element (especially, piezoelectric) increases the risk of damaging it and raises questions on the reliability of the energy harvester. In order to overcome this shortcoming, we proposed a transverse mechanical impact driven frequency up-converted hybrid energy harvester for human-limb motion. It utilizes the integration of both piezoelectric and electromagnetic transducers in a given size that allows more energy to be harvested from a single mechanical motion, which, in turn, further improves the power density. While excited by human-limb motion, a freely-movable non-magnetic sphere exerts transverse impact by periodically sliding over a seismic mass attached to a double-clamped piezoelectric bimorph beam. This allows the beam to vibrate at its resonant frequency and generates power by means of the piezoelectric effect. A magnet attached to the beam also takes part in generating power by inducing voltage in a coil adjacent to it. A mathematical model has been developed and experimentally corroborated. At a periodic limb-motion of 5.2 Hz, maximum 93 µW and 61 µW average powers (overall 8 µW·cm−3 average power density) were generated by the piezoelectric and the electromagnetic transducers, respectively. Moreover, the prototype successfully demonstrated the application of low-power electronics via suitable AC-DC converters.

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A novel hybrid energy harvester with increased power density

Procedia Engineering ◽

10.1016/j.proeng.2017.09.464 ◽

2017 ◽

Vol 199 ◽

pp. 3498-3503

Author(s):

M. Moshrefi-Torbati ◽

T.V. Lang ◽

M. Hendijanizadeh ◽

T.B. Le ◽

S.M. Sharkh

Keyword(s):

Power Density ◽

Energy Harvester ◽

Hybrid Energy ◽

Hybrid Energy Harvester

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Performance Analysis of a Piezoelectric Bimorph Cantilevered and Electromagnetic Hybrid Energy Harvester

2018 IEEE SENSORS ◽

10.1109/icsens.2018.8589924 ◽

2018 ◽

Author(s):

Sara Zolfaghar Tehrani ◽

Hossein Ranjbar ◽

Peter Vial ◽

Prashan Premaratne

Keyword(s):

Performance Analysis ◽

Energy Harvester ◽

Piezoelectric Bimorph ◽

Hybrid Energy ◽

Hybrid Energy Harvester

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Double-Deck Metal Solenoids 3D Integrated in Silicon Wafer for Kinetic Energy Harvester

Micromachines ◽

10.3390/mi12010074 ◽

2021 ◽

Vol 12 (1) ◽

pp. 74

Author(s):

Nianying Wang ◽

Ruofeng Han ◽

Changnan Chen ◽

Jiebin Gu ◽

Xinxin Li

Keyword(s):

Kinetic Energy ◽

Power Density ◽

Energy Harvester ◽

High Efficiency ◽

Vibrational Energy ◽

Average Power ◽

Wafer Level ◽

Peak Voltage ◽

Silicon Mold ◽

Casting Technique

A silicon-chip based double-deck three-dimensional (3D) solenoidal electromagnetic (EM) kinetic energy harvester is developed to convert low-frequency (<100 Hz) vibrational energy into electricity with high efficiency. With wafer-level micro electro mechanical systems (MEMS) fabrication to form a metal casting mold and the following casting technique to rapidly (within minutes) fill molten ZnAl alloy into the pre-micromachined silicon mold, the 300-turn solenoid coils (150 turns for either inner solenoid or outer solenoid) are fabricated in silicon wafers for saw dicing into chips. A cylindrical permanent magnet is inserted into a pre-etched channel for sliding upon external vibration, which is surrounded by the solenoids. The size of the harvester chip is as small as 10.58 mm × 2.06 mm × 2.55 mm. The internal resistance of the solenoids is about 17.9 Ω. The maximum peak-to-peak voltage and average power output are measured as 120.4 mV and 43.7 μW. The EM energy harvester shows great improvement in power density, which is 786 μW/cm3 and the normalized power density is 98.3 μW/cm3/g. The EM energy harvester is verified by experiment to be able to generate electricity through various human body movements of walking, running and jumping. The wafer-level fabricated chip-style solenoidal EM harvesters are advantageous in uniform performance, small size and volume applications.

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Power Density Improvement of Piezoelectric Energy Harvesters via a Novel Hybridization Scheme with Electromagnetic Transduction

Micromachines ◽

10.3390/mi12070803 ◽

2021 ◽

Vol 12 (7) ◽

pp. 803

Author(s):

Zhongjie Li ◽

Chuanfu Xin ◽

Yan Peng ◽

Min Wang ◽

Jun Luo ◽

...

Keyword(s):

Power Density ◽

Output Power ◽

Energy Harvester ◽

Hybrid Energy ◽

Energy Harvesters ◽

Piezoelectric Patch ◽

Piezoelectric Energy ◽

Electromagnetic Transduction ◽

Self Powered ◽

Power Densities

A novel hybridization scheme is proposed with electromagnetic transduction to improve the power density of piezoelectric energy harvester (PEH) in this paper. Based on the basic cantilever piezoelectric energy harvester (BC-PEH) composed of a mass block, a piezoelectric patch, and a cantilever beam, we replaced the mass block by a magnet array and added a coil array to form the hybrid energy harvester. To enhance the output power of the electromagnetic energy harvester (EMEH), we utilized an alternating magnet array. Then, to compare the power density of the hybrid harvester and BC-PEH, the experiments of output power were conducted. According to the experimental results, the power densities of the hybrid harvester and BC-PEH are, respectively, 3.53 mW/cm3 and 5.14 μW/cm3 under the conditions of 18.6 Hz and 0.3 g. Therefore, the power density of the hybrid harvester is 686 times as high as that of the BC-PEH, which verified the power density improvement of PEH via a hybridization scheme with EMEH. Additionally, the hybrid harvester exhibits better performance for charging capacitors, such as charging a 2.2 mF capacitor to 8 V within 17 s. It is of great significance to further develop self-powered devices.

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