Not only can walking increase your own energy, but it may also increase the energy of your portable electronic devices. Scientists at Osaka Metropolitan University made a significant advance toward self-charging wearable devices with their invention of a dynamic magnifying glass-enhanced piezoelectric vibration energy collector that uses impulsive vibrations such as small energy harvesters currently being developed. The results were published in Applied physics letters.
Nowadays, people carry a variety of electronic devices such as smartphones, and portable devices are expected to become more widespread in the near future. The resulting demand for more efficient charging of these devices has increased attention to energy harvesting, a technology that converts energy such as heat and light into electricity that can power small devices. A form of energy harvesting called vibrational energy harvesting is considered very practical because it can convert the kinetic energy of vibrations into electricity and is unaffected by weather or climate.
A research team led by Associate Professor Takeshi Yoshimura of the Graduate School of Engineering at Osaka Metropolitan University has developed a microelectromechanical system (MEMS) piezoelectric vibration energy collector that is only about 2 cm in diameter and features a U-shaped metal component, which is called a dynamic magnifier. Compared to traditional harvesters, the new harvester enables about a 90-fold increase in energy converted from impulsive vibrations that can be generated by human walking movements.
The team has been working to develop vibrational energy harvesters that use the piezoelectric effect, a phenomenon in which certain types of materials generate an electrical charge or voltage in response to applied pressure. So far, they have succeeded in generating electricity in the microwatt range from mechanical vibrations with a constant frequency, such as those generated by motors and washing machines. However, the power production of these harvesters drops drastically when the applied vibrations are non-stationary and impulsive, such as those produced by human walking.
In response to this challenge, the team designed and integrated the U-shaped vibration amplification component under the harvester. The component enabled an improvement in power generation without increasing device size. The technology is expected to generate electrical energy from unsteady vibrations, including walking motions, to power small wearable devices such as smartphones and wireless headphones.
Professor Yoshimura concluded: “As electronic devices are expected to become more energy efficient, we hope that this invention will contribute to the realization of self-charging portable devices.”
Materials provided by Metropolitan University of Osaka. Note: Content can be edited for style and length.