Biodegradable Battery for Medical Use

Scientists at the University of Illinois at Urbana-Champaign have recently developed biodegradable batteries that don’t need to be removed surgically. The battery is a flexible electronic component that will dissolve in water and inside the body after three weeks.

Researchers designed an imaging system that will monitor tissues and thermal paths after the surgical site has been closed. The anodes used in the battery are magnesium foil, and the cathodes are made of molybdenum, iron, or tungsten. Their ions are biodegradable in low concentrations, and their metals will dissolve in the body without unhealthy side effects. The entire battery system is packed with polyanhydride. It uses a phosphate-buffered saline solution as an electrolyte between the two electrodes.

The project took off in 2009 when researchers brought the expertise of John Rogers on flexible silicon electronics and the biocompatible silk of Omenetto. They made the silk by processing and moulding the proteins from the silkworm cocoons to make thin sheets to stick and conform to the tissues such as the surface of the brain. Then the researchers placed the silicon integrated circuits together with light-emitting diodes and other electronic devices. While the devices did not show adverse effects during initial animal testing, researchers found that the metals didn’t really dissolve and the silicon floats under the skin.

Recently, scientists and researchers have figured out how every part of the battery system dissolves. Instead of silver or copper, they used magnesium because it is conductive but reactive. Magnesium was used to connect circuits and form wires and antennas to allow these devices to be powered outside the body.

The thin membrane is less than 100 nanometers thick and dissolves at 4.5 nanometers daily. However, their optical and electrical properties are not compatible with the current techniques used by semiconductors industry.

The team is now working to scale up the production of silicon-silk components. This is a huge step forward in the battery technology to help doctors monitor patients’ vital organs and deliver treatments easily. This could also lead to nerve-regeneration scaffolds, and drug delivery devices. And, once the treatment is over; the device will disappear without a trace.