Artificial heart technology has come a long way since the first clunky device that went into a patient in 1969. But one thing that artificial hearts have lacked is valve technology that can twist like a valve of a human heart twists when blood pumps through it.
That is all poised to change thanks to new soft robotic technology out of Harvard's Wyss Institute for Biologically Inspired Engineering and Harvard's School of Engineering and Applied Sciences (SEAS), which simulates real heart-valve movement and could improve future artificial-heart technology.
The reason the heart twists with the movement of blood through it is because of bundles of striated muscle fibers, which spiral in the same direction and work together to achieve motion, according to researchers.
Researchers at Harvard University have designed a soft robotic cardiac simulator that can move with a 3D motion similar to how an actual heart valve twists when blood pumps through it. The top images show the team's heart prototype as it is subjected to various pressures. The middle images show a computer model of the mesh only as it deforms at corresponding pressures, and below is a computer model showing how the heart PAMs and mesh change their motion in response to the different pressure regimes. (U indicates displacement.)
(Source: Harvard University)
The Wyss-SEAS team set out in November 2012 to mimic those muscle fibers, and have achieved a successful facsimile through the development of a modified pneumatic artificial muscle (PAM) made from soft silicone elastomer with embedded braided mesh, Ellen Roche, an MD/PhD candidate at SEAS and a member of the research team told Design News.
Silicone elastomer was used because it “has a stiffness within the range of cardiac tissue,” she said. “We could manufacture the actuators and embed them in a matrix made out of the same low stiffness silicone.”
The muscle was attached via tubing to an air supply and moves “via small pneumatic actuators embedded in a soft matrix in a specific orientation that is inspired by muscle arrangement in the heart,” Roche said.
More specifically, the matrix consists of several of the artificial muscles embedded together. By changing their orientation and configuration within the matrix and applying pressure, researchers could achieve various motions in more than one direction, an action that mimics the heart’s own complex motion.
In this way, the soft robotic cardiac simulator built by researchers “simulates 3D motion and left ventricular twist,” Roche added, something that valves in artificial hearts currently do not do.
Researchers modeled simulations of the muscles’ movements in 3D, which allowed them to successfully create the prototype.
The next phase for the research, which could mean a significant breakthrough in the design of future artificial hearts, is to adapt the technology to develop implantable cardiac assist devices, Roche told us. Researchers are currently working on this implantable device with the help of a team at an unidentified children’s hospital.