Powering smart devices is still one of the main issues to get devices into mainstream adoption. A wearable device is only good if it is functional. There have been very initiative solutions on batteries and quick charge innovation. This issue with battery reliability was being worked on by an Israeli company named StoreDot. They are claiming to have created a battery that can charge your phone in less than 5 mins. https://www.store-dot.com/ Another way to generate battery power for wearable is from kinetic energy. The transfer of kinetic energy to power wearables is an interesting concept. For example, a cyclist could use the kinetic energy from pedals to power the GPS device on the bike. https://www.cnet.com/news/ampy-motion-powered-backup-battery-stores-kinetic-energy/ More recently, Caltech university has developed a way to convert sweat to power wearable devices. The design involves the use of lactate, a natural byproduct of human sweat. The possibility of using sweat power to wearables such as prosthetics, smartwatches and smart glasses over Bluetooth is intriguing. To see more about Wei Gao from Caltech on sweat power click below:   http://www.gao.caltech.edu/research.html