Biodegradable battery that dissolves inside the body

This is about a device that can monitor tissues or deliver treatments inside the body before being reabsorbed after use.

A four-cell biodegradable, implantable battery is here that can help in the development of such biomedical devices.

The battery, developed by materials scientist John Rogers from University of Illinois and collaborators, uses anodes of magnesium foil and cathodes of iron, molybdenum or tungsten.

All these metals would slowly dissolve in the body and their ions are biocompatible in low concentrations.

"Once dissolved, the battery releases less than 9 milligrams of magnesium - roughly twice as much as a magnesium coronary artery stent that has been successfully tested in clinical trials, and a concentration that is unlikely to cause problems in the body," Rogers explained.

Almost all of the key building blocks are now available to produce self-powered, biodegradable implants, he said.

"This is a really major advance. Until recently, there has not been a lot of progress in this area," added Jeffrey Borenstein, a biomedical engineer at Draper Laboratory, a nonprofit research and development centre in Cambridge, Massachusetts.

The team hopes to improve the batteries' power per unit weight - known as power density - by patterning the surface of the magnesium foil to increase its surface area, which should enhance its reactivity.

The authors estimated that a tiny battery could realistically power a wireless implantable sensor for a day.

It has environmental applications too.

To help remediation efforts during an oil spill, environmental officials could drop hundreds of thousands of tiny wireless chemical sensors across the slick.

These would later simply dissolve in the ocean.

Space is less of a constraint in these applications: a stack of several cells, for instance, can produce up to 1.6 volts - enough to power a light-emitting diode or generate a radio signal.

These batteries could eventually yield implantable drug-delivery devices that are controlled by radio signals, said the report in the journal Advanced Materials2.