Actor Christopher Reeve died of an infection resulting from a pressure ulcer, commonly known as a bedsore, following years of paralysis. While bedsores do not commonly cause death, they affect an estimated 2.5 million Americans each year and often become difficult to treat. Now, engineers at UC Berkeley are developing a new “smart bandage” that uses electrical currents to detect early tissue damage from bedsores before they become visible — and while recovery is still possible.

"We are beginning a small clinical trial at UCSF," Dr. Michel Maharbiz, associate professor of electrical engineering and computer sciences at UC Berkeley, told Medical Daily. If all goes well, then, smart bandages may soon be available for use.

Bedsores, which are injuries to the skin and underlying tissue, develop most often on skin that covers bony areas of the body, such as the hips and tailbone. People at risk for these pressure ulcers are those who are confined to a bed or, like Reeve, people with medical conditions requiring use of a wheelchair. The increasing prevalence of diabetes and obesity has increased the risk for bedsores, which can develop quickly and cause considerable pain and expense.

The odds of a hospital patient dying are nearly three times higher when they have pressure ulcers, according to some research.

“By the time you see signs of a bedsore on the surface of the skin, it's usually too late,” Dr. Michael Harrison, a professor of surgery at UCSF and a co-author of the new study, said in a press statement.

Beneath the Surface

"My group had been considering ideas for monitoring the state of wounds (and maybe eventually affect wound healing) using technology for a few years," Maharbiz told Medical Daily.

As leader of the research project, he envisioned a bandage that could detect bedsores as they are forming below the surface of the skin. To accomplish this, the research team thought about the electrical changes that occur whenever a healthy cell begins to die. Normally, a cell's membrane is relatively impermeable and acts essentially like an insulator to the cell's conductive contents. However, as a cell starts to die, the integrity of its walls also begin to break down, allowing electrical signals to leak out as they would from a broken resistor.

Based on this model, the researchers began the creation of a smart bandage by printing an array of electrodes onto a thin, flexible film. They found that a small current discharged between the electrodes would create a spatial map of any underlying tissue based upon electricity flows at different frequencies. (This technique involved impedance spectroscopy.)

To test their new bandage, the researchers needed a test subject, so they gently squeezed the bare skin of rats between two magnets as a way to mimic a pressure wound. After removing the magnets, resumption of normal blood flow caused inflammation and damage that accelerated cell death in the rats. Next, the researchers attached the non-invasive "smart bandage" to the skin of the injured rats. With consistency, the bandage was able to detect varying degrees of tissue damage, invisible to the human eye, across multiple animals and tracked the progress of the wounds.

For more information, watch the UC Berkeley video below:

Source: Swisher SL, Lin MC, Liao A, et al. Impedance sensing device enables early detection of pressure ulcers in vivo. Nature Communications. 2015.