Researchers have developed an alternative to general delivery of pain medication to bring relief to post-surgical patients or those who’ve been fitted with a prosthetic by using a tiny circuit that can localize pain management within tissues.

Researchers have developed biodegradable micro-resonators that can be heated locally with a wireless system. Doctors could soon be using them in implants to control the release of painkillers within tissue. (Image source: Ecole Polytechnique Fédérale de Lausanne)

Researchers at L’Ecole Polytechnique Fédérale de Lausanne (EPFL) have developed biodegradable micro-resonators that they can heat locally and remotely with a wireless system that can be built into implants to release painkillers within human tissue, eliminating the need for invasive procedures like injections or catheters to deliver medication. The devices also could help prevent any ill effects of medications from affecting other parts of the body, researchers said.

Specifically, a team in EPFL’s Microsystems Laboratory at the School of Engineering developed a micro-sized electronic circuit–a resonant circuit in the shape of a small spiral–that is made from magnesium, a biocompatible material already found in the human body.

The spiral resonator produces an electric current that creates heat when exposed to an alternating electromagnetic field, which could be used to release controlled amounts of anesthetic in a specific location over several days, researchers said. Because the device is biodegradable, it will dissolve harmlessly when its work is through, they said.

Timing Is Everything

Because the success of medication release depends on its timing, scientists had to ensure the resonators could work in a way that supports this aspect of the technology.

To do this, they fabricated resonators with different medicine capsules that can be controlled using different frequencies, said Mattieu Ruegg, a PhD student who worked on the project. “That means we could release the contents of the capsules individually by selecting different frequencies,” he said in a press statement.

To use the technology, the painkiller-filled capsules would be inserted into the appropriate tissue during surgery. Then, their contents would be released when an electromagnetic field sent from outside the body melts the capsule membrane using heat, a process that should take less than a second.

Researchers published a paper on their work in the journal Advanced Functional Materials.

Fabrication Considerations

One challenge researchers faced when developing the micro-resonator was the fabrication process, which needed to consider the water solubility of magnesium, Ruegg noted.

“We immediately ruled out any fabrication process that involved contact with water, since magnesium dissolves in just a few seconds,” he said in the release.

Researchers solved the problem by depositing the magnesium on a substrate and then sprinkling it with ions to shape it, giving the team some flexibility in the design stage, Ruegg said in the press statement. This allowed he and his colleagues to create magnesium resonators two microns thick with a diameter of three millimeters—some of the tiniest created to date, he said.

The team still has some work ahead of it to fabricate micro-resonators that can be used for human patients, Ruegg acknowledged. Researchers plan to continue their research by integrating resonators in a prototype device to prove that mediations can be delivered both in vitro and in vivo, he said.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco and New York City. In her free time she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.