Today wearables require a battery for operation. Until now, energy harvesting on the human body was in most cases not sufficient to power an embedded system or simply too expensive. On the one hand, our newly developed energy-autarkic measuring system for shoes provides enough energy for an embedded system. On the other hand, it can also compete with battery-based solutions on the price side.

The power supply is realized by energy harvesting from the walking motion. A piezoelectric harvester converts kinetic energy into electrical energy. The power management stores the energy in a capacitor and provides it to an embedded system. It measures the force at four positions and counts the number of steps. A microcontroller prepares the data and sends it via Bluetooth Low Energy (BLE) to a smartphone. There, the data is stored, evaluated, and visualized.

The energy harvesting from the walking motion is fully sufficient to operate the embedded system. At each step, data can be acquired and sent wirelessly using Bluetooth Low Energy (BLE). No additional power supply via batteries or rechargeable batteries is required.

The presented solution is applicable as an energy-autarkic measuring system in wearables or medical applications, such as shoes, walking aids, walking sticks, medical bracings or prostheses. The developed energy harvesting principle can be easily transferred to other application areas where a mechanical force occurs.