Hsu Wins NSF CAREER Award to Develop Energy-Saving Wearable Device

January 25, 2022 | Elizabeth Witherspoon

Competitive five-year grant will help Po-Chun Hsu develop new wearable technology to manage heat around the human body without using additional power supply

Po-Chun Hsu standing with hands in pockets at top of stairs with hanging orange sculpture in background

Po-Chun Hsu, assistant professor of mechanical engineering and materials science at Duke University, has been awarded a prestigious National Science Foundation Faculty Early Career Development (CAREER) Award. The award supports outstanding early-career faculty in building a foundation for a lifelong research program. For the next five years, the $500,000 award will support Hsu’s innovative work developing a wearable device that manages heat around the human body without requiring an active power supply to maintain the heating/cooling mode.

Hsu’s goal is to address the human need for thermal homeostasis—or maintenance of core body temperature within a specific range, as required by all warm-blooded mammals—while reducing the enormous amount of energy consumption and carbon emissions associated with indoor temperature control.

According to the U.S. Department of Energy and other sources, building heating and cooling management accounts for an estimated 15% of global energy consumption and approximately 10% of global greenhouse gas emissions. Hsu is passionate about reducing these levels of energy consumption and their environmental effects.

“My goal is to solve the long-standing trade-off between power consumption and functionality of wearable thermoregulation devices by providing a new approach of controlling heat transfer, rather than actively supplying power, which will significantly reduce energy consumption,” said Hsu.

His approach for the device supported by this award involves a combination of materials science, thermal science, sustainability and photonic engineering. The design uses a metamaterial—an engineered composite that is structured to control and manipulate light waves—to radiate heat. By pairing the metamaterial with a polymer that electrochemically changes its property, Hsu will tune the device to manage the heat that naturally radiates from the human body in the mid-infrared wavelength range, thereby optimally regulating the body’s heat balance. Mid-infrared wavelengths are between the visible light spectrum and microwaves.

“The electrochemical tuning is non-volatile and consumes zero power to maintain the heating/cooling mode, which is a remarkable advantage for long-term daily usage,” said Hsu.

To provide stretchability, breathability and morphing of the dynamic metasurface in 3D for future large-scale production, Hsu will employ kirigami cuts, which are akin to origami but combined with cutting that render 3D results without adhesive.  

Hsu sees potential in this device for both spurring the cross-disciplinary field of photonic engineering, sustainable energy science and providing better-personalized thermoregulation to prevent temperature-related diseases, such as heart attack, stroke, heat illness, colds, and flu.

Hsu already has a strong track record of achievements to address energy consumption for heating and cooling, publishing extensively about his findings. He developed a device using customized nanomaterials with specific properties that are able to change between heating and cooling modes to manage solar energy for both radiative heating and cooling of a building.

His most recent work in textiles uses physics rather than electronics to open vents in a hybrid nylon/silver nanomaterial to let heat escape when a person begins to sweat, then reclose to retain heat once they are dry.

He also has designed comfortable textiles for wearables with specific properties to lower wearers’ thermal radiation so that they can tolerate higher air-conditioning settings. His approach is a departure from existing textiles, which wick moisture away from the body as their cooling method.  Listen to him describe his materials science work at the nanoscale on “The World’s Coolest T-Shirt” episode of Duke Engineering’s Rate of Change podcast and on this episode of Science podcast.

Hsu joined Duke’s Thomas Lord Department of Mechanical Engineering & Materials Science in 2019. He earned a PhD in materials science at Stanford University in 2016.