Researchers have developed a hair-thin battery that can power robots as small as a punctuation mark.
Zinc-Air Battery extracts oxygen from the surrounding environment and oxidizes tiny amounts of zinc, a reaction that can generate 1 volt. This energy can then power sensors or small robotic arms capable of lifting and lowering objects, such as delivering insulin directly into the cells of a diabetic.
While ultra-small robots have long been proposed for delivering medication to specific locations within the body, powering them has remained a challenging issue.
A tiny battery powering a robot (Photo: Michael Strano).
Many current designs rely on solar power, meaning they must be exposed to sunlight or controlled by lasers. However, both options cannot penetrate deeply into the body as they always need to be connected to a light source.
Senior research author Michael Strano, a chemical engineer at MIT, stated: “If you want a tiny robot to enter spaces that humans cannot reach, it needs to have a higher degree of autonomy.”
Battery Size: 0.01 Millimeters
This is one of the smallest batteries ever invented. In 2022, researchers in Germany described a millimeter-sized battery that could fit on a microchip. Strano and his team’s battery is about 10 times smaller, measuring just 0.1 millimeters long and 0.002 millimeters thick (the average human hair is about 0.1 millimeters thick).
This battery consists of two components: a zinc electrode and a platinum electrode. They are embedded in a polymer called SU-8. When zinc reacts with oxygen from the air, it undergoes an oxidation reaction that releases electrons. These electrons flow to the platinum electrode.
The battery is produced using a process called photolithography, which employs photosensitive materials to transfer nanometer-sized patterns onto silicon wafers. This method is commonly used in semiconductor manufacturing. It can quickly “print” 10,000 batteries on a single silicon wafer, as reported by Strano and his colleagues in the journal Science Robotics.
In this new study, researchers used a wire to connect these tiny batteries to ultra-small robots developed at Strano’s lab. They tested the battery’s ability to power a memristor.
They also used the ultra-thin battery to power a clock circuit, allowing the robot to keep track of time and power two nano-sized sensors, one made from carbon nanotubes and the other from molybdenum disulfide. Such micro-sensors can be inserted into pipelines or other hard-to-reach areas, according to the researchers.
The research team also utilized the battery to move an arm on one of the ultra-small robots. These tiny movements could enable medical robots to operate inside the body, delivering medication at a specific time or location.
