The future in which someone who has lost an arm can control a robotic hand simply by attempting to move the limb—and, furthermore, regain the ability to feel contact with objects—is already beginning to take shape. Researchers in the United States are moving in this direction with a new generation of bionic prostheses.

In Chicago, a team from the Shirley Ryan AbilityLab, in collaboration with Northwestern Medicine, performed an experimental surgery that combines three technologies: an implant fixed directly to the bone, sensors installed in the muscles, and electrodes positioned around the nerves. The first U.S. participant in this study, who lost his left arm in a workplace accident in 2016, underwent an approximately eight-hour operation during which doctors installed a titanium structure into his arm bone and implanted components designed to capture muscle signals—with the future goal of also transmitting sensory feedback.

Just a few weeks later, the researchers were able to demonstrate part of the system’s functionality: when the patient attempts to move his missing hand, his remaining muscles produce electrical signals. These signals are captured by sensors and interpreted by an artificial intelligence, which identifies the intended movement and reproduces it in a robotic demonstration arm—though the ultimate objective goes well beyond simply moving a prosthesis.

The researchers also aim for the user to receive sensory feedback upon contact with objects, achieved through electrical stimuli delivered to the nerves; this capacity to restore sensations will be further evaluated throughout the study. At this initial stage, the patient has not yet demonstrated the full functionality of a definitive prosthesis with restored tactile sensation, and this research is part of a much broader transformation.

For decades, artificial prostheses were essentially mechanical devices that relied on the user’s own strength and movements. Today, some bionic legs already incorporate motors, sensors, and computers to detect whether a person is walking, climbing stairs, or navigating a ramp. In research conducted by this same laboratory in Chicago, these systems are able to adjust the level of assistance provided to the user during various movements.

This allows, for instance, a motorized prosthesis to help propel the body upward when climbing stairs, rather than merely following the movement passively. As these interfaces become more advanced, the effort required to control the equipment can be significantly reduced. The major challenge now is to transition artificial arms and legs from functioning as external tools to responding increasingly naturally to a person’s intentions. While significant obstacles remain—such as cost, durability, the need for surgery, and the individual adaptation process for each patient—the results demonstrate that the convergence of medicine, robotics, and artificial intelligence is creating possibilities that, until recently, seemed to belong to the realm of science fiction.