Wonder material is elastic and thermally conductive Monday, 20 February 2017

It sounds like a character from a children's show but 'thubber' is a new thermally conductive rubber material that could be used to create soft, stretchable machines and electronics.

The material, developed at Carnegie Mellon University in Pennsylvania, exhibits metal-like thermal conductivity while at the same time having an elasticity similar to soft, biological tissue that 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 of mechanical engineering at Carnegie Mellon.

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.

To demonstrate these findings, 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.

“As the field of flexible electronics grows, there will be a greater need for materials like ours,” said Majidi. “We can also see it used for artificial muscles that power bio-inspired robots.”

In addition to athletic wear and biomedicine, the researchers believe there are also application in advanced manufacturing, energy, and transportation.

“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 another member of the team, Jonathan Malen, also an associate professor of mechanical engineering.

“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.”

[A soft robotic fish swims using a thubber tail. Image: Carnegie Mellon University]