New, lightweight, stretchable polymer foam could potentially be used as synthetic human heart

23-Oct-15

A new, lightweight, stretchable polymer foam developed by scientists at Cornell University has connected pores to allow fluids to be pumped through it, meaning it could potentially be used as an synthetic human heart or another type of artificial organ. The polymer foam, which starts out as a liquid, can be poured into a mold to create a variety of different shapes. It could be used to create prosthetic body parts or soft robotics, lead author Rob Shepherd, an assistant professor of mechanical and aerospace engineering at the school, and his colleagues explained in the latest edition of the journal Advanced Materials. Due to the fluid pathways present in this “elastomer foam”, air or liquids pumped through it can move and alter its length by up to 300 percent, the researchers said. While applications inside the human body will still require testing and approval from federal regulators, Shepherd said that his team might soon be able to use the material to develop a prosthetic hand. The material is made porous by mixing salt with the rubbery elastomer when it is still a liquid, the researchers explained. Once the elastomer cures and hardens, the salt is removed. When a prosthetic limb or organ needs to be sealed so that air or fluid pumped through cannot escape, a salt-free version of the same polymer is used to coat the outside. In their paper, Shepherd and his colleagues explained that they used a combination of silicone and carbon fiber on the outside to create a structure with a surface that expands at different rates. This could be used to change a spherical shape into an egg shape. “This paper was about exploring the effect of porosity on the actuator, but now we would like to make the foam actuators faster and with higher strength, so we can apply more force,” Shepherd, whose research was funded by the Air Force Office of Scientific Research, the National Science Foundation and 3M, said. He added that his team is also “focusing on biocompatibility.” The latest study builds on separate research published last month in which the Cornell team said that they had fabricated a 3D printed elastomer that could be used to create layers of duplicated octopus tentacle muscles. Those synthetic muscles had nearly the same kind of agility and range of motion as a real tentacle, something previously unachievable with 3D printing.