By ELIZA STRICKLAND

The inside of the human body is mostly squishy (that’s a technical term), and our soft innards don’t always fare well when hard objects are placed inside. Not only can sharp edges damage organs and blood vessels, but the body’s defense system can also surround the foreign object with scar tissue and interfere with its intended function. So researchers are working on soft robots that may be better tolerated within the body, permitting machines to make intimate contact with human tissue without jeopardizing safety.

These three experimental bots are designed for different purposes—two are implants, one is a potential surgical tool—but they all showcase a gentler kind of robotics, enabled by new materials and flexible actuators.

Heart Hugger

Inside the chests of 41 million people around the world, failing hearts gradually become less effective at the vital task of pumping blood. Some heart failure patients get on the list for a transplant, while others receive metallic pumps called ventricular assist devices (VADs) to help their faltering organs. But VADs increase the risk of blood clots, which can form as the liquid flows over surfaces made of metal and plastic.

In search of a better pumping assistant, an international team of researchers invented a silicone sleeve that slips over the heart’s exterior, thus keeping the robot from contact with flowing blood as it rhythmically squeezes the organ. The sleeve’s design is inspired by the arrangement of real heart muscles, with an inner layer of material that contracts using concentric rings and an outer layer that contracts in a helical fashion. The early-stage device uses 14 pneumatic actuators (6 in the concentric layer, 8 in the helical layer), which the team can activate individually by filling them with air, allowing for experimentation with different patterns of contractions. In experiments with live pigs, the researchers demonstrated that the device can either detect and match the natural rhythm of the heart or override a faulty rhythm with a steady beat.[Read More]