Engineering news
Researchers at the Ecole Polytechnique Federale de Lausanne (EPFL) in Switzerland have created an implant that can release a local anaesthetic on demand over the course of several days. It’s designed for patients being fitted with an orthopaedic prosthetic, who commonly experience a period of intense pain after surgery.
In an effort to control the pain, surgeons inject painkillers into the tissue during the operation. When that wears off a day or two later, the patients are given morphine through a catheter placed near the spine. But catheters are not particularly comfortable, and the drugs spread throughout the body, affecting all organs.
Research, published in the journal Advanced Functional Materials, describes a new approach. The scientists developed a tiny biodegradable electronic circuit, made from magnesium, that could be heated wirelessly from outside the body.
Once integrated into the final device, the circuit will allow to release controlled amounts of anaesthetic in a specific location over several days. After that, the implant will degrade safely inside the body.
The electronic circuit is just a few microns thick, and when exposed to an alternating electromagnetic field, it produced an electric current that created heat. The end goal is to pair such a resonator with a painkiller-filled capsule and insert them into tissue during surgery – allowing the painkillers to be released on demand when an electromagnetic field from outside the body melts the capsule membrane. "We're at a key stage in our project, because we can now fabricate resonators that work at different wavelengths," says Matthieu Rüegg, a PhD student and the study's lead author. "That means we can release the contents of the capsules individually by selecting different frequencies."
To manufacture such a tiny device, the researchers had to develop a new approach. "We immediately ruled out any fabrication process that involved contact with water, since magnesium dissolves in just a few seconds," says Rüegg. They ended up shaping the magnesium by depositing it on a substrate and then showering it with ions. "That gave us more flexibility in the design stage," he adds. They were eventually able to create some of the smallest magnesium resonators in the world: two microns thick, with a diameter of three millimetres.
It will be a while before their device is ready for use in the real world, however. "We still need to work on integrating the resonators into the final device and show that it's possible to release drugs both in vitro and in vivo," concludes Rüegg.