3D printing flexible wearables generate electricity with body temperature

From health monitoring and fitness trackers to virtual reality headsets, wearable electronics have become part of our daily lives. Researchers at the University of Washington recently published a paper in the journal Advanced Energy Materials that they pioneered a flexible wearable thermoelectric device that can convert body heat into electricity. The device has properties that are often difficult to combine: both soft and stretchable, robust and efficient.

Mohamed Malacudi, assistant professor of mechanical industry at the University of Washington, said: "If we collect the thermal energy wasted in the surrounding environment, this is a 100% benefit." But to use this energy for self-powered electronics, higher power densities are required. Stretchable electronics made with 3D printing can improve efficiency and enable seamless integration into wearable devices. ”

The researchers created a prototype device that remains fully functional even after more than 15,000 stretch cycles at 30 percent strain, ideal for wearable electronics and flexible robots. Compared to previous stretchable thermoelectric generators, the power density of this device is increased by 6.5 times.

To make this prototype device, the researchers 3D printed composite materials with engineered functions and structural properties at each layer, filled with liquid metal alloys that provide high electrical and thermal conductivity. These alloys address the limitations of previous equipment, including inability to stretch, inefficient heat transfer, and complex manufacturing processes. The team also embedded hollow microspheres that direct heat to the semiconductors in the core layer and reduce the weight of the device.

The researchers say they can print the device on stretchable textile fabrics and curved surfaces, suggesting that future devices could be applied to clothing and other objects. A unique aspect of the study is that it covers the entire spectrum from materials synthesis to device fabrication and characterization, giving researchers the freedom to design new materials and be creative.

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