15-year-old invents shoe insole that can charge a phone

Mumbai: A piezoelectric device is a simple electronic module, which is made up of a crystal sandwiched between two electrodes. When the crystal moves or vibrates, it generates electricity. Similarly, when you pass electrical pulses to the electrodes, the crystal vibrates, and this principle is used in piezoelectric buzzers you find in electronic birthday cards and small toys.

Angelo Casimiro, a 15-year-old high school kid from Philippines has managed to create a super simple, yet extremely cheap form of an electricity generator, which can charge portable devices by simply moving around.

In fact, the project was started almost five years ago, but he managed to finalize it eventually. The idea is to have a few piezoelectric transducers (or buzzers) below the insole of the shoe and connected to a small circuit and a rechargeable battery. When pressed by the weight of the person, the transducers bend and the crystal moves to create a small amount of electricity. Using multiple transducers, he managed to collect and amplify the amount of electricity to a fairly usable range, enough to charge a small portable device.

According to Angelo, when he measured the output voltage of the circuit by simply pressing it with his hands, he recorded 15.03V @ 2mA and while using it under his feet, he recorded a voltage of 27.89V @11mA. After a basic test, he stated that the power output is presently sufficient for charging a mobile phone battery with 10 minutes of power after playing basketball for almost two hours.

Angelo has put up the entire project with a step-by-step guide on Instructables so that others can follow it and make one too.

The project is a beginning and will take more power efficient resources to get to a level where it can charge a full battery in shorter time.