A team of researchers at Carnegie Mellon have developed a biodegradable battery derived from cuttlefish ink.
The Carnegie Mellon team has developed the battery and tested its power storage capacities, but no one has taken the big swallow yet. "I'm thinking about doing it at some point," said Professor Christopher Bettinger, one of the researchers. The team's findings were recently published in the Proceedings of the National Academy of Sciences (paywall).
The battery could be used to make new medicine delivery systems for drugs that are currently administered as shots. "One of the first applications that we think is going to be interesting is in controlled release," said Bettinger. "Delivering drugs through the oral route can overcome a lot of the challenges that people have with injections." The biodegradable battery could be used to create controlled release devices that can be swallowed like a pill, but would be able to release medicine after passing through the stomach. Many drugs cannot be taken orally, because they would be destroyed before they could be useful.
Now that the prototype battery has been created, the team is working on delivery systems for specific medical applications. The batteries could power devices that are able to sense where they are in the digestive tract, and deliver things like vaccines or arthritis drugs.
Bettinger explains that these batteries aren't optimized for power density or the ability to be recharged, but rather for bio-compatibility. The sodium-ion batteries are made from melanin and manganese oxide, which break down into nontoxic components. The melanin is derived from cuttlefish ink.The Carnegie Mellon team was interested in using naturally occurring melanin thanks to its "disordered, semi-conducting" nano structure. They found that natural melanin, which is also found in the human body in lower concentrations, has a higher charge storage capacity than lab-made melanin.
Although this battery is made from bio-compatible materials, it may pass through the digestive system without breaking down because the battery doesn't deteriorate particularly quickly. "It's on the order of weeks or months," said Bettinger.
The biodegradable battery makes edible electronics safer for use in the body than conventional batteries. "If it gets stuck in the body, it's not a big deal," he said.
The team is also continuing to research melanin's electro-conductive properties. "If we can understand that process with a higher degree of certainty, then maybe we can engineer new materials that have more interesting properties."
Outside of medicine, there are many exciting potential uses for a biodegradable battery. Bettinger suggested that the batteries could power biodegradable devices that act as sensors or monitors in other types of sensitive environments.
"Imagine there's an oil spill and you want to know what's in it," he said. One could drop devices into the ocean that could communicate with each other and send messages back to researchers. "Then when the battery is dead the device could disintegrate into the natural environment."