The power source can dissolve after three weeks in water.
John Rogers, a professor of materials science and engineering at the University of Illinois at Urbana-Champaign, and his research team have developed a fully biodegradable battery that dissolves inside the body after three weeks in water.
Rogers had previously led research on biodegradable electronic components that could be used in medical implants and eco-friendly smart devices. The biodegradable electronics, however, ran on wireless power from an external source and wireless power transfer wouldn’t do well with implants that need to go deeper within tissue or bone. That’s where the biodegradable battery would become more useful.
The biodegradable battery uses anodes of magnesium foil and cathodes of iron, molybdenum or tungsten – metals that will dissolve in the body and have ions that are biocompatible in low concentrations. The device uses a phosphate-buffered saline solution as the electrolyte between the electrodes and the entire system is encased in polyanhydride, a biodegradable polymer.
The current and voltage depends on the metal used for the cathode. Once the battery dissolves, it releases magnesium in a concentration that isn’t harmful to the body, according to Rogers. The researchers were able to prototype several versions that could maintain a steady output of power for over a day but not longer. The team hopes to improve the power density or power per unit weight of the battery by increasing the surface area of the magnesium foil to increase its reactivity.
The biodegradable device has several potential uses, including environmental applications wherein the device can be turned into a chemical sensor that assesses an oil spill and simply dissolve afterwards, as well as biomedical implants that deliver drugs as controlled or in response to time-sensitive events like epileptic seizures.
The research was published last week on Advanced Materials.