MIT Researchers Develop Minuscule Batteries for Cell-Sized Robots

MIT scientists have created hair-size zinc-air batteries capable of powering cell-sized robots. These internal energy sources harness oxygen from their surroundings to oxidize zinc, generating up to 1 volt. This innovation could revolutionize applications such as drug delivery and remote sensing, where traditional power methods fall short.

Traditionally, the challenge of powering tiny robots has led to designs reliant on solar power, known as "marionettes" due to their dependence on external light sources. These configurations are limited in scope since sunlight or lasers cannot penetrate deep into the body, curtailing their movement.

Senior author Michael Strano, a chemical engineering professor at MIT, emphasized the importance of autonomy in small robots. Unlike marionettes, which draw energy externally, robots equipped with these new batteries can operate independently. "A battery is essential for any robot aiming to access otherwise unreachable spaces," Strano said.

Devised from zinc and platinum electrodes embedded in SU-8 polymer, each battery is 0.1 millimeters long and 0.002 millimeters thick, similar to a human hair. The configuration involves a zinc electrode oxidizing and releasing electrons toward the platinum electrode, creating an electric current. This process can generate enough energy to power tiny components, such as sensor arrays or robotic actuators.

These pioneering batteries were crafted using photolithography, a process where light-sensitive materials transfer intricate patterns onto silicon wafers. This efficient technique allows MIT's team to produce 10,000 batteries per silicon wafer.

To demonstrate their application, MIT researchers connected the batteries to nanoscale robots, which could perform varied tasks—like operating memristors that alter resistance according to charge, and clock circuits for timekeeping. Moreover, the batteries enabled two specialized nanosensors made from carbon nanotubes and molybdenum disulfide, enhancing their potential for leak detection in inaccessible areas.

Strano's lab is expanding on these basic building blocks, aiming to embed the batteries within the robots to eliminate external connections. Such innovation might permit medical robots to deliver drugs like insulin to specific cells at specified times. Looking ahead, the team aims to incorporate the batteries fully into their robotic designs, potentially increasing battery voltage to expand utility.

Strano envisions these autonomous robots supporting diverse applications, such as medical interventions and pipeline maintenance, with eventual hopes of biocompatible constructions suitable for human use. The ongoing research, funded by entities like the U.S. Army Research Office and the Department of Energy, promises a transformative leap in both robotic technology and energy use.

"We're structuring robotic functions around an internal power source," Strano stated, "forming the core of an array of robotic developments."

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