New design process accelerates the discovery of advanced materials

Flexible materials that combine mechanical flexibility with high thermal or electrical conductivity are essential for wearables, stretchable electronics and soft robotic systems. To identify new composite materials with those properties, researchers typically create and test many different material formulations, a process that can be time-consuming, expensive and lead to waste. , 天美影院researchers developed a new 鈥渋nverse design framework鈥� that reverses the standard design process to speed up the discovery of multifunctional materials. The framework starts with the desired material properties for a specific application 鈥� such as wearable electronics 鈥� and works backward to determine the optimal material composition using physics-based modeling and machine learning. Experiments showed that a material identified by the framework achieved about 60% higher thermal conductivity while reducing material cost by about 10%, compared to materials that were previously used.聽

For more information, contact senior author , 天美影院assistant professor of mechanical engineering.聽

The other co-authors are Lijun Zhou, Yunsik Ohm, Ren-Mian Chin, Olivia Kerr and Krithika Manohar.

Climate models get a vote of confidence in a new 天美影院study mapping tropical ocean temperature over time

Climate models help researchers understand how conditions are changing over time to forecast what is likely to happen in the future. Predicting extreme heat, drought or flooding years in advance can give people time to prepare, but the accuracy of these predictions varies. Scientists test models by asking them to recreate past climate and comparing those predictions with observational data. Although modern climate models get a lot of things right, they often fail to replicate recent temperature change in the tropical Pacific Ocean, a key region for global weather. This has concerned scientists, but a 天美影院study offers a glimmer of hope. The researchers found that climate models could successfully replicate temperature trends in the equatorial Pacific when they expanded the window of observation by 20 years. Including more data allowed the models to better account for climate variability, which can create long-lasting fluctuations in temperature and precipitation that aren鈥檛 always indicative of a general trend.聽

For more information, contact senior author Matt Luongo, 天美影院postdoctoral fellow in the Cooperative Institute for Climate, Ocean, & Ecosystem Studies and School of Oceanography at mluongo@uw.edu.

The other 天美影院co-author is . A full list of co-authors is .

Paternal body odor increases brain-to-brain synchrony with infants

Infant brains recognize their fathers as unique social partners, showing stronger brain-to-brain synchrony with their fathers compared to unfamiliar males during social interactions. A new study also shows that when infants interact with unfamiliar males while exposed to their fathers鈥� body odor, their brain synchrony increases to levels similar to those seen with their own fathers. Further, exposure to paternal body odor increased infants’ positive arousal. These findings suggest that infants use their fathers鈥� scent as an important social cue, even when the father is not physically present. Researchers also found that father-infant synchrony involved a different neural rhythm than previously observed in mother-infant interactions, suggesting that mothers and fathers may support development through complementary neural pathways. Combined, these findings reveal a previously unknown role of paternal body odor as a sensory signal that contributes to early social and brain development.

For more information, contact , co-author and a research scientist in the 天美影院Institute for Learning and Brain Sciences.聽

The other co-authors are Linoy Schwartz and Ruth Feldman.

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Electronic waste is piling up around the world , partly because to recover useful materials from discarded gadgets. When processed improperly, spent electronics to lead, mercury and other toxic chemicals. Without systemic changes, our global appetite for electronics could produce an annual .

This conundrum inspired a team at the 天美影院 to create an easily recyclable material that could one day replace many traditional circuit boards, the foundation of most electronics. The new material is flexible, self-healing and can be made conductive without additional components.

This suite of features could help produce a more sustainable generation of wearable electronics, soft robotics and more.

鈥淲e created a lot of functionality within one material,鈥� said senior author , a 天美影院assistant professor of mechanical engineering. 鈥淥ur goal is to build a widely useful platform for flexible, reusable devices.鈥�

in Advanced Functional Materials.聽

Conventional circuit boards pass electrical signals through conductive metal traces, which are bonded to a rigid board commonly made of fiberglass and resin. In contrast, the new material is a soft and stretchable composite made from a recyclable polymer infused with microscopic droplets of a liquid metal alloy based on gallium. A circuit can be created on this composite by lightly scoring a pattern into its surface, which connects adjacent embedded droplets and allows electricity to flow. The rest of the material remains electrically insulating.聽

has been experimenting with liquid metal-infused polymers since 2019 鈥� the team uses . It鈥檚 proven to be a promising class of materials, but the rising cost of the liquid metal motivated the team to focus on reusability.

The new composite has a few tricks up its sleeve. The polymer holding the liquid metal droplets is still stretchy and strong, but it can be broken down through a simple chemical process, freeing the metal for reuse. In experiments, researchers recovered 94% of the metal from their samples.

The composite also has self-healing properties. Users can cut the material into pieces, rearrange them, and bond them back together using only heat and pressure. An electrical circuit chopped up in this manner will still function when reconnected in a new configuration.

Malakooti envisions a new wave of electronics built with composites like this one, but also a new paradigm for use and reuse. Instead of mass producing gadgets and then tossing them out, he argues, we could design devices and their components to be used, repaired, reconfigured and ultimately recycled.聽

鈥淲e鈥檙e trying to make a difference now to shape the future of flexible and wearable electronics,鈥� Malakooti said. 鈥淲e can鈥檛 make all these devices and then go back and try to figure out how to recycle them. That鈥檚 how we ended up with the electronic waste problem we face today. I want to tackle this problem from the very start.鈥�

Co-authors include , a 天美影院doctoral student of mechanical engineering; , a 天美影院undergraduate student of mechanical engineering; and , and at the Oak Ridge National Laboratory.

This research was funded by the National Science Foundation and the Department of Energy.

For more information, contact Malakooti at malakoot@uw.edu.

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One of the drawbacks of fitness trackers and other wearable devices is that their batteries eventually run out of juice. But what if in the future, wearable technology could use body heat to power itself?

天美影院researchers have developed a flexible, durable electronic prototype that can harvest energy from body heat and turn it into electricity that can be used to power small electronics, such as batteries, sensors or LEDs. This device is also resilient 鈥� it still functions even after being pierced several times and then stretched 2,000 times.

The team published Aug. 30 in Advanced Materials.

“I had this vision a long time ago,” said senior author , 天美影院assistant professor of mechanical engineering. “When you put this device on your skin, it uses your body heat to directly power an LED. As soon as you put the device on, the LED lights up. This wasn’t possible before.”

Traditionally, devices that use heat to generate electricity are rigid and brittle, but Malakooti and team so that it can conform to the shape of someone’s arm.

This device was designed from scratch. The researchers started with simulations to determine the best combination of materials and device structures and then created almost all the components in the lab.

It has three main layers. At the center are rigid thermoelectric semiconductors that do the work of converting heat to electricity. These semiconductors are surrounded by 3D-printed composites with low thermal conductivity, which enhances energy conversion and reduces the device’s weight. To provide stretchability, conductivity and electrical self-healing, the semiconductors are connected with printed liquid metal traces. Additionally, liquid metal droplets are embedded in the outer layers to improve heat transfer to the semiconductors and maintain flexibility because the metal remains liquid at room temperature. Everything except the semiconductors was designed and developed in .

In addition to wearables, these devices could be useful in other applications, Malakooti said. One idea involves using these devices with electronics that get hot.

“You can imagine sticking these onto warm electronics and using that excess heat to power small sensors,” Malakooti said. “This could be especially helpful in data centers, where servers and computing equipment consume substantial electricity and generate heat, requiring even more electricity to keep them cool. Our devices can capture that heat and repurpose it to power temperature and humidity sensors. This approach is more sustainable because it creates a standalone system that monitors conditions while reducing overall energy consumption. Plus, there鈥檚 no need to worry about maintenance, changing batteries or adding new wiring.”

These devices also work in reverse, in that adding electricity allows them to heat or cool surfaces, which opens up another avenue for applications.

“We’re hoping someday to add this technology to virtual reality systems and other wearable accessories to create hot and cold sensations on the skin or enhance overall comfort,” Malakooti said. “But we’re not there yet. For now, we’re starting with wearables that are efficient, durable and provide temperature feedback.”

Additional co-authors are , a 天美影院doctoral student in mechanical engineering, and , who completed this research as a 天美影院postdoctoral scholar in mechanical engineering and is now an assistant professor at Izmir Institute of Technology. Malakooti and Han are both members of the 天美影院Institute for Nano-Engineered Systems. This research was funded by the National Science Foundation, Meta and The Boeing Company.

For more information, contact Malakooti at malakoot@uw.edu.

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