MIT researchers have developed an incredibly small zinc-air battery—smaller than a grain of sand—that could soon power autonomous, cell-sized robots for tasks like targeted drug delivery and leak detection in pipelines. This battery is only 0.1 millimeters long and 0.002 millimeters thick, roughly equivalent to the thickness of a human hair, yet it can generate up to 1 volt by capturing oxygen from the air. The oxidation of zinc by the captured oxygen produces a current strong enough to run tiny circuits, sensors, or actuators.
Michael Strano, a professor of Chemical Engineering at MIT, explained that this innovation is a major step forward for robotics, as it enables the integration of robotic functions directly into the battery itself. This development was led by researchers Ge Zhang and graduate student Sungyun Yang, with their work recently documented in Science Robotics.
Strano’s lab has long been exploring ways to create tiny robots that can sense and react to their surroundings. One of the main hurdles has been providing sufficient power in such a small package. While previous approaches have used external light sources to power microdevices, those systems require constant external energy and limit the robots’ autonomy. By embedding a power source like this zinc-air battery into the robots, they could operate independently and access confined or remote spaces.
Zinc-air batteries are prized for their high energy density and long lifespan, which is why they’re often used in hearing aids. The MIT battery design features a zinc electrode paired with a platinum electrode, both embedded within a polymer commonly used in microelectronics. As oxygen interacts with these electrodes, zinc oxidizes and releases electrons, thereby generating an electrical current.
In laboratory tests, the battery successfully powered a small actuator—demonstrating the movement of a robotic arm—as well as a memristor, which can record events by changing its electrical resistance, and a clock circuit that helps keep time. It also provided enough energy to run two different chemical sensors, one constructed from atomically thin molybdenum disulfide and the other from carbon nanotubes.
Strano emphasized that these basic components could serve as the foundation for constructing fully functional, cell-scale robotic systems. Although the current experiments involved a wired connection to external devices, future designs will integrate the battery directly into the robots, much like how an electric car is built around its battery.
One promising application under investigation is the creation of microscopic robots that could be injected into the human body. These robots might be used to locate specific sites and deliver drugs like insulin. For such medical applications, the devices would be made from biocompatible materials that safely break down after completing their task.
The team is also working on methods to increase the battery’s voltage, which could broaden its range of applications even further.
Funding for this research came from several sources, including the U.S. Army Research Office, the U.S. Department of Energy, the National Science Foundation, and a MathWorks Engineering Fellowship.
