In an ideal world we wouldn’t need to charge our wearable devices at all. The term energy harvesting captures several different approaches that lead us to a world where we might not need to charge our wearable devices at all! There is a whole range of new technologies on the rise that could help make wearable devices rely less on power outlets and instead harvest energy from other sources.
While you might know these from rooftops or solar panel parks, much smaller versions of these could provide enough energy to power wearable devices. One of the current problems with solar cells is that they only work when directly exposed to the light. This makes solar energy harvesting an interesting option for smart clothes and where these cells can be woven into the textile. The typical solar cell is designed to absorb sunlight, which is much brighter than something like an office light. To address this issue, new solar cells are being developed to not only produce energy indoors, but also at a higher efficiency.
This type of energy harvesting transforms heat into electric energy. This energy uses a pair of semiconductors, which produce an electrical current when one side is warmer than the other. When it comes to wearable technology and the human body, the body is always emitting heat. So, when it comes to wearable devices, the human body could be used as the side, while the cold outside air could be used for thermoelectric harvesting. One of the biggest benefits is that the energy is always available, day and night.
This type of energy converts shocks or vibrations into electrical energy. For energy harvesting in wearables, the piezoelectric elements are often designed to produce energy with the vibrations that occur when walking, breathing or moving your hands. Piezoelectric technology generally generates a small amount of energy and thus limits the technology that can be used. Scientists are working on polymeric piezoelectric fibres that can not only be integrated into textiles, but also are flexible, strong and breathable.
Energy harvesting is part of the story when it comes to wearable technology, the other half is storing the energy. The smartphone’s success has lead to powerful and energy-efficient processors for mobile devices, activity trackers, smart watches and other smart devices. When it comes to improving the storage of energy for wearable technology, graphene and structural capacitors will help not only improve the efficiency of batteries, but also help with the amount of space needed for a separate battery. All these improvements can help make these wearable devices self-powering.