Harvesting Energy for Wearables

The market for wearable devices (from bracelets and watches to smart apparel) has exploded in recent years and is predicted to keep growing. While the functions of these gadgets and the data they’re capable of collecting are becoming more and more futuristic, the way they’re powered is as well. Many brands are developing ways to tap into new energy sources — from harnessing it from sunlight, to capturing it with each step you take — to keep these gadgets running. That not only means they could be easier and less expensive to use, but also that your favorite wearables may be becoming more sustainable. Here’s a roundup of what might soon power our favorite health and fitness monitors.

Light

Photovoltaic is the term describing energy that’s collected from an external light source. Even indoor lighting can be taken and converted back into wattage, but sunlight has much more power-revving potential. It is already used in gadgets such as wireless keyboards and could be developed for use in data-gathering devices as well. One way this technology is being researched is to trap photovoltaic cells in glass particles and weave them into fabric to be used for smart clothing items. In the future, those clothes could potentially track fitness stats such as calories burned during a jog.

Heat

Energy trapped from a heat source (which is termed thermovoltaic energy) can be used on a very large scale. It’s even been used by NASA. As it pertains to use among consumers, though, heat-harvested energy is most commonly seen in fabrics. Since our bodies are constantly emitting heat, the potential to harness it through fabrics and convert it to energy is massive. Thermoelectric cells can take body heat and apply it to electrons, then carry it through the process of generating energy. However, the presence of clothing changes the pattern of heat loss across the body. Heat typically escapes at the highest rate from bare skin, and people lose the most heat through their heads, not on parts of the body that are typically covered with clothes. More research is being done about the best ways to harvest body heat and use it to power wearables.

Movement

Another possible way to generate energy for wearables is to harness power from movement or vibrations. One company exploring this strategy is Harvest, which gathers energy from a user’s daily movement and transforms it through an electromagnetic process. The device is placed in a user’s shoe or pocket or on a bicycle pedal, for instance, and stores energy as he or she walks, runs or bikes. The pod can later be plugged into a smartphone and will display the user’s fitness stats. The user can also upload the power they’ve generated and use it or donate it, so this process can help whittle away at your carbon footprint too.

Electromagnetic Radio Waves

Scientists are looking into the feasibility of powering medical devices that are injected into or implanted in the body with electromagnetic radio waves. These could include tech pieces like heart probes, pacemakers and gadgets used during minimally invasive surgery — devices that traditionally include bulky batteries. Engineering professors at Stanford University are experimenting with ways to have patients wear an external radio transmitter that wirelessly sends energy signals to the implanted devices inside their bodies. Once the electricity has been transmitted, it can propel devices through the bloodstream.

Your Body

Possibly the most intuitive idea about how to harness energy for wearable devices is to capture it directly from inside the wearer’s body. Technologies to gather energy from heartbeats, the expansion and deflation of lungs and the contractions of a diaphragm are being explored for various uses. Researchers at the University of Illinois at Urbana-Champaign, for instance, have been exploring new technology that can capture energy from the pulse of a beating heart and convert it to a few milliwatts of power. So far, the resulting amount of power is negligible, but it’s enough to keep a pacemaker working. (For essential devices such as pacemakers, though, researchers say for now, it’s smarter to use a hybrid of harvested energy along with a standard battery.)

Most of these new strategies for powering devices are still being researched and developed, and many are limited to medical devices at the moment. But watch for them to make an appearance in the wearables market soon.