This series of reports from WTiN will provide an in-depth analysis of the energy harvesting effects that enable power to be generated from the human body within wearable applications.

Part I: Covers harvesting energy from human body motion for wearable applications, detailing the principles of triboelectric, electromagnetic and piezoelectric energy harvesting. 

Here in the second part, we will cover; how the energy generated from human body heat can be converted into electrical energy, via the pyroelectric and thermoelectric effect or by harvesting biofuels such as human perspiration.

• Pyroelectric energy harvesting uses a time-varying temperature to convert heat into electrical energy, however, a time-varying temperature is difficult to achieve within wearable applications. Therefore, this report will focus on energy harvesting via the thermoelectric effect using a temperature gradient, as this is much easier to achieve between the human body and a wearable device.
• Additionally, biofuels such as the lactate in human perspiration can be utilised for the generation of electricity via wearable biofuel cells. This approach is another appealing avenue to power smart wearable devices and will therefore be detailed further within this report.