Thermal conductivity + elasticity = “thubber”

Carmel Majidi and Jonathan Malen of Carnegie Mellon University have developed a thermally conductive rubber material that they’ve nicknamed “thubber.” According to information provided by the Carnegie Mellon University College of Engineering, the new material is an electrically insulating composite that exhibits a combination of metal-like thermal conductivity and elasticity similar to soft, biological tissue. And it can stretch over six times its initial length.

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 has proven to be electrically insulating.

Majidi, associate professor of mechanical engineering, notes that the combination of high thermal conductivity and elasticity aid rapid heat dissipation in applications such as wearable computing and soft robotics. Applications could include sports medicine and athletic wear in the form of heated garments for injury therapy and lighted clothing for nighttime exercising. The researchers also see possibilities for the material to be used for artificial muscles that power bio-inspired robots.

Majidi and Malen acknowledge the efforts of lead authors Michael Bartlett, Navid Kazem and Matthew Powell-Palm in performing this multidisciplinary work. They also acknowledge funding from the Air Force, NASA and the Army Research Office. Their findings were published recently in Proceedings of the National Academy of Sciences.