Harnessing kinetic energy from human motion and converting it into usable electrical energy has become in recent years an attractive approach to powering wireless electronic devices. The harvesters can be connected to electronics in garments and footwear that are able to track physical parameters such as speed, movement and temperature.
An innovative energy harvesting system has been developed based on emergent electroactive polymers, which is small enough to be embedded in the sole of a shoe. The mechanical-to-electrical converter device is based on thin films of polymers of large relative permittivity. As compared with traditional piezoelectric concepts, this device works non-resonantly and can be optimized for harvesting energy from mechanical power sources also in the low frequency range.
A first device demonstrator of a polymer energy harvester embedded in a shoe is now available. This is able to generate several µWs of energy when subjected to mechanical deformation of pressure and frequency range specific to human walking. The harvester circuit has been adjusted to power an RF transmitter module.
The harvester system (device and circuit) can be adapted for other applications such as for powering wireless sensors and portable electronic devices.