'Thubber' may lead to soft, stretchable electronics

In a breakthrough for creating soft, stretchable machines and electronics, scientists have developed a novel rubber material with high thermal conductivity and elasticity.
The material, nicknamed 'thubber', is an electrically insulating composite that exhibits an unprecedented combination of metal-like thermal conductivity, elasticity similar to soft, biological tissue, and can stretch over six times its initial length.
"Our combination of high thermal conductivity and elasticity is especially critical for rapid heat dissipation in applications such as wearable computing and soft robotics, which require mechanical compliance and stretchable functionality," said Carmel Majidi, an associate professor at Carnegie Mellon University in the US.

Applications could extend to industries like athletic wear and sports medicine - think of lighted clothing for runners and heated garments for injury therapy.
Advanced manufacturing, energy, and transportation are other areas where stretchable electronic material could have an impact, researchers said.
"Until now, high power devices have had to be affixed to rigid, inflexible mounts that were the only technology able to dissipate heat efficiently," said Jonathan Malen, an associate professor at Carnegie Mellon University.

"Now, we can create stretchable mounts for LED lights or computer processors that enable high performance without overheating in applications that demand flexibility, such as light-up fabrics and iPads that fold into your wallet," said Malen.

The key ingredient in "thubber" is a suspension of non-toxic, liquid metal microdroplets. The liquid state allows the metal to deform with the surrounding rubber at room temperature.
When the rubber is pre-stretched, the droplets form elongated pathways that are efficient for heat travel. Despite the amount of metal, the material is also electrically insulating.
The team mounted an LED light onto a strip of the material to create a safety lamp worn around a jogger's leg.
The "thubber" dissipated the heat from the LED, which would have otherwise burned the jogger. The researchers also created a soft robotic fish that swims with a "thubber" tail, without using conventional motors or gears.

The findings were published in the journal Proceedings of the National Academy of Sciences.