New vanishing electronic medical implants dissolve inside the body

Medical implants such as pacemakers and defibrillators have helped to revolutionize the medical industry by aiding organs that would otherwise give way to failure.  However, current implants are typically designed to last forever, and when the time comes when they are no longer needed, surgery is often necessary to remove them.

But what if electronic implants could simply disappear when they were no longer needed?  Biomedical engineers at Tufts University and the University of Illinois at Urbana-Champaign have addressed that particular problem by creating tiny, fully functional electronics capable of vanishing within their environment.

Completely biocompatible with human tissues, these aptly named “transient electronics” are being considered a revolutionary new class of electronic devices.  Their development could lead to future medical implants that do not need surgical removal, as well as the creation of other environmental and consumer electronics that do not leave behind trash but dissolve into the environment.

The researchers and engineers came up with their invention hoping to address a core problem with medical implants – rejection.

““It’s an issue of long term biocompatibility,” John Rogers, a professor in the department of mechanical science and engineering at UIUC and a corresponding author on the study, told “….We were wondering whether there would be a way to make electronics that would resolve those problems – vanishing after [they’ve] served [their] useful lifetime. Electronics that are physically transient, so they can [dissolve] in water or biofluids.”

Looking to develop such technology, Rogers and his fellow researchers set about to identify the right materials that would provide high performance, but also be biodegradable.  Rogers said that thin sheets of silicon, a common ingredient in modern integrated circuits, were used as semi-conductors.

“[Silicon] is water soluble, but the dissolution rates are so low,” Rogers explained, which is why it is a valuable material for electronics.  “But these are ultra thin geometries, so those low rates become important.”

Magnesium, another integrated circuit material, was used as the device’s electrode.   And for their most unique ingredient, the team utilized purified material from the cocoons of silk worms – an FDA approved material – as a substrate and packaging material.

Combining these ingredients, the team was able to construct a very tiny biomedical implant in mice, which was used to eliminate a common complication with many surgeries.

“That is the growing problem associated with surgery – surgical sight infection,” Rogers said.  “Infection of that source is the leading cause of readmission to the hospital.  It is often times a result of bacteria colonies at the sight of surgery.”

According to Rogers, the device was a thin sheet of electronic, located at the sight of surgery before the patient – in this case the mouse – before they are closed up.  Capable of receiving power wirelessly, the device creates local heating at levels that can kill bacteria that may be forming at the sight of surgery.

However, the risk of infection from surgery is the most critical two weeks after the initial period – rendering the device unnecessary in just a short time.  The device was programmed to start dissolving after that two-week period.  When the researchers examined the mice three weeks after the device was originally implanted, they found that infection had been reduced and only a very faint traces of the implant remained.

While the device tested for the paper was designed to degrade passively, the research team has hopes of developing implants that can be wireless triggered in order to dissolve when they are no longer needed.  With further development, transient electronics could have a whole range of applications.

“Maybe a transient pacemaker, which eventually degrades and disappears,” Rogers said.  “We like thermal intervention, but there is also electrical stimulation.  It is known that electrical stimulation of bones can stimulate bone growth, so it can be used on fractures to help them heal.  Then after the bone is healed, [the implant] naturally disappears.”

Going beyond medical applications, Rogers and his team imagine that this invention could revolutionize the entire electronics industry.  By developing electronic devices that naturally degrade into the environment, there is less waste left behind and the environment is less harmed.

“We want to exploit the fact that we’re using a silicon based device,” Rogers said.  “It allows us to leverage the established electronics industry, and modify existing integrated circuits. They are relatively modest modifications of what’s out there today.”