A Bioresorbable Electric Bandage Offers Hope to Diabetics

Researchers at Northwestern University have developed an innovative stretchy bandage that not only hastens healing with electricity but also has sensors to alert diabetes patients and doctors wirelessly of the progress of healing.

Published in the journal Science Advances, “Bioresorbable, wireless battery-free system for electrotherapy and impedance sensing at wound sites,” is a study that this first bioresorbable bandage can deliver electrotherapy and is the first example of a smart regenerative system. In an animal study, the new bandage healed diabetic ulcers 30 percent faster than in mice without the bandage.

“When a person develops a wound, the goal is always to close that wound as quickly as possible,” said Northwestern’s Guillermo A. Ameer. He said, “Otherwise, an open wound is susceptible to infection. And, for people with diabetes, infections are even harder to treat and more dangerous. For these patients, there is a major unmet need for cost-effective solutions that really work for them. Our new bandage is cost-effective, easy to apply, adaptable, comfortable and efficient at closing wounds to prevent infections and further complications.”

The first-of-its-kind bandage also actively monitors the healing process and then harmlessly dissolves — electrodes and all — into the body after it is no longer needed. The new device could provide a powerful tool for patients with diabetes, whose ulcers can lead to various complications, including amputated limbs or even death.

“Although it’s an electronic device, the active components that interface with the wound bed are entirely resorbable,” said Northwestern’s John A. Rogers .“As such, the materials disappear naturally after the healing process is complete, thereby avoiding any damage to the tissue that could otherwise be caused by physical extraction,” he said.

Power of electricity

Nearly 30 million people in the U.S. have diabetes, and about 15 to 25 percent of that population develops a diabetic foot ulcer at some point. Because diabetes can cause nerve damage leading to numbness, diabetes sufferers experience simple blister or small scratch that goes unnoticed and untreated. But high glucose levels thicken capillary walls, thus slowing blood circulation and making healing more difficult. It’s a perfect way for a small injury to become a dangerous wound.

Ameer and Rogers wanted to know if electrical stimulation therapy could help close these stubborn wounds. According to Ameer, injuries can disrupt the body’s normal electrical signals. By applying electrical stimulation, it restores the body’s normal signals, attracting new cells to migrate to the wound bed.

“Our body relies on electrical signals to function,” Ameer said. “We tried to restore or promote a more normal electrical environment across the wound. We observed that cells rapidly migrated into the wound and regenerated skin tissue in the area. The new skin tissue included new blood vessels, and inflammation was subdued.”

Historically, clinicians have used electrotherapy for healing. But most of that equipment includes wired, bulky apparatuses that can only be used under supervision in a hospital setting. To design a more comfortable product that could be worn around the clock at home, Ameer partnered with Rogers, a bioelectronics pioneer who first introduced the concept of bioresorbable electronic medicine in 2018.

Remote control

The two researchers and their teams ultimately developed a small, flexible bandage that softly wraps around the injury site. One side of the smart regenerative system contains two electrodes: A tiny flower-shaped electrode that sits right on top of the wound bed and a ring-shaped electrode that sits on healthy tissue to surround the entire wound. The other side of the device contains an energy-harvesting coil to power the system and a near-field communication (NFC) system to wirelessly transport data in real time.

The team also included sensors that can assess how well the wound is healing. By measuring the resistance of the electrical current across the wound, physicians can monitor progress. A gradual decrease of current measurement relates directly to the healing process. So, if the current remains high, then physicians know something is wrong.

By building in these capabilities, the device can be operated remotely without wires. From afar, a physician can decide when to apply the electrical stimulation and can monitor the wound’s healing progress.

“As a wound tries to heal, it produces a moist environment,” Ameer said. “Then, as it heals, it should dry up. Moisture alters the current, so we are able to detect that by tracking electrical resistance in the wound. Then, we can collect that information and transmit it wirelessly. With wound care management, we ideally want the wound to close within a month. If it takes longer, that delay can raise concerns.”

In a small animal model study, the researchers applied electrical stimulation for just 30 minutes a day. Even this short amount of time accelerated the closure by 30 percent.

Disappearing act

When the wound is healed, the flower-shaped electrode simply dissolves into the body, bypassing the need to retrieve it. The team made the electrodes from molybdenum: a metal widely used in electronic and semiconductor applications. The researchers found that when molybdenum is thin enough, it can biodegrade. Furthermore, it does not interfere with the healing process.

“We are the first to show that molybdenum can be used as a biodegradable electrode for wound healing,” Ameer said. “After about six months, most of it was gone. And we found there’s very little accumulation in the organs. Nothing out of the ordinary. But the amount of metal we use to make these electrodes is so minimal, we don’t expect it to cause any major issues.”

Next, the team plans to test their bandage for diabetic ulcers in a larger animal model. Then, they aim to test it on humans. Because the bandage leverages the body’s own healing power without releasing drugs or biologics, it faces fewer regulatory hurdles. This means patients potentially could see it on the market much sooner.

An expert in regenerative engineering, Ameer is a professor of biomedical engineering at Northwestern’s school of engineering and also teaches surgery at Northwestern University's Feinberg School of Medicine. Rogers is a professor of material science, engineering, and neurological surgery at Northwestern. He also directs the Querrey Simpson Institute for Bioelectronics.