Babies born with an esophagus that’s disconnected from their stomachs can spend weeks in intensive care. But tiny robots may change that. Researchers have developed a small cylindrical pouch of motors and sensors encased in a waterproof skin that extends tube-shaped organs such as the esophagus. The robot does this by gently pulling on tissue like a kid stretching silly putty, which encourages new tissue to grow. To find out how well the implant works, researchers tested the device in pigs. They attached the implants to the animals’ healthy, connected esophagi with two steel rings that wrap around the organ like pincers. Using an external controller that keeps track of how much the robot pulls on the organ and how far it stretches, researchers increased the distance between the rings by about 2.5 millimeters each day for about a week and a half. That helped the pigs’ esophagi grow about 77% longer in this region, the team reports today in Science Robotics. While their esophagi lengthened, the pigs were awake, able to move around and eat normally. That suggests people, and children especially, could tolerate the device, the researchers say.