A small device can harvest energy from the breeze generated as you walk and could potentially be used to power your gadgets
Source:
https://www.newscientist.com/article/2255057-device-can-harvest-wind-energy-from-the-breeze-made-when-you-walk/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home