A thermally conductive rubber material was developed that represents a breakthrough for creating soft, stretchable machines and electronics. The new material, nicknamed “thubber,” is an electrically insulating composite that exhibits a combination of metal-like thermal conductivity and elasticity similar to soft, biological tissue that can stretch more than six times its initial length.
The combination of high thermal conductivity and elasticity is critical for rapid heat dissipation in applications such as wearable computing and soft robotics, which require mechanical compliance and stretchable functionality.
Applications could extend to industries like athletic wear and sports medicine for lighted clothing for runners, and heated garments for injury therapy. Advanced manufacturing, energy, and transportation are other areas in which stretchable electronic material could have an impact.
Previously, high-power devices have been affixed to rigid, inflexible mounts that were the only technology able to dissipate heat efficiently. Stretchable mounts can now be created for LED lights or computer processors that enable high performance without overheating in applications that demand flexibility such as lighted fabric tablet computers that can fold up into a wallet.
The key ingredient in the material is a suspension of nontoxic, 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, an LED light was mounted 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.