Caltech researchers create sweat-powered wearable

This wearable e-skin is powered by human sweat.
Image: Dr. Wei Gao

Many people overlook the fact that the human body is a huge producer of energy. For companies looking to create tiny wearables, that energy output is a key area of research. Recently, scientists from Caltech created a skin-like wearable that runs solely on human sweat.

It doesn’t need any form of external power. Yet, it is capable of monitoring vital signs and even allows wearers to control devices like robotic arms and prosthetics. It could be a huge breakthrough for the wearables world and may serve as a viable way to power devices of the future.

The Power of Sweat

The idea of using sweat to power wearable devices isn’t an entirely new concept. Researchers have tossed the idea around for years. Due to the fact that it is rich in electrolytes and other organic materials, sweat is a great source of fuel.

Caltech researcher Wei Gao and his team designed a sort of e-skin that runs on lactate—a byproduct of human sweat. What makes their gadget different from others that use sweat is the fact that it doesn’t need any form of external power. The skin-like patch has no battery packs, no charging cables, not even a wireless charger.

Even so, it is powerful enough to carry out some impressive functions. The patch features a suite of sensors that let it monitor the human body in ways that are comparable to much more powerful devices.

After attaching the skin-like wearable it monitors things like temperature, heart rate, blood sugar levels, and even some nerve signals.

The device works thanks to fuel cells integrated into its surface. These absorb lactate from sweat and combine it with oxygen in the air. The reaction generates enough electricity to power its various sensors and a Bluetooth transceiver that connects to a smartphone.

Easy Transmission

According to lead researcher Wei Gao, seeing a Bluetooth chip in a sweat-powered wearable isn’t common. He says, “While near-field communication is a common approach for many battery-free e-skin systems, it could be only used for power transfer and data readout over a very short distance.”

Gao adds, “Bluetooth communication consumes higher power but is a more attractive approach with extended connectivity for practical medical and robotic applications.”

In a video with CNET, Gao demonstrates the wearable’s ability to control other gadgets wirelessly. A person wearing the patch on their arm generated enough electricity to power a fairly sophisticated prosthetic leg. Moreover, another wearer used it to control a robotic arm. It followed the movements of their arm (albeit with some lag) to reach and grasp an object.

Going forward, Gao and his team are planning to develop several additional sensors that are compatible with the e-skin. He says, “We want this system to be a platform. In addition to being a wearable biosensor, this can be a human–machine interface. The vital signs and molecular information collected using this platform could be used to design and optimize next-generation prosthetics.”

The team’s research is published in the journal Science Robotics.


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