Researchers at EPFL have developed a new biodegradable circuit that can be implanted to deliver painkillers to a specific location in the body on demand. When the device is heated up from a source outside the body, it releases a controlled amount of a drug over several days, before safely dissolving away when it's no longer needed.

The device is built around what's known as a microresonator, measuring 3 mm (0.1 in) wide and just two microns thick. Made of magnesium, these microresonators have a spiral shape and will generate a small electric current when exposed to an alternating electromagnetic field. In turn, that current creates heat that can melt capsules containing certain drugs.

In practice, that design means that the microresonator can be implanted to release drugs on demand. When painkillers are needed, the device is activated by applying an electromagnetic field from outside the body, which melts the capsules and releases the drugs. That keeps the dosage controlled and localized to where the device is. Then once it's been used up, the microresonator dissolves, so there's no need to surgically remove it.

The team says that the device can be tweaked to respond to specific wavelengths, melting different capsules at different times to release the drugs on demand and in sequence. It should only take about a second after heating for the drug to be released.

The device is fabricated by first depositing the magnesium on a substrate, then showering it with ions to shape the material into the desired structure. This process is what allowed the researchers to make it so thin.

The aim of the new device is to make for a less invasive pain relief system, particularly for patients who need intense drugs after surgery. Those who need an orthopedic prosthetic, for example, often receive morphine through a catheter implanted near the spine. But this is not the most comfortable nor precise delivery method.

While the idea is interesting, the team still hasn't tested the entire device – so far, they've only made the resonators. The next steps will be to integrate the drug capsules, then show that it works to release them in the lab and, eventually, in the body.

The research was published in the journal Advanced Functional Materials.

Source: EPFL

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