Chronic wounds affect up to 6 million patients in the United States and more than $20 billion is spent on their treatment each year, so even modest reductions in healing time are beneficial.

A team of Drexel researchers have an ideal solution. They’ve developed an inexpensive, wristwatch-size instrument that can speed up slow-healing injuries. Since the device is compact, lightweight and portable, patients may one day be able to use it in their homes, avoiding the high costs and other inconveniences associated with frequent doctor’s office visits.

The device heals by sending low-frequency — 20 kilohertz (kHz) — ultrasonic sound waves directly to the chronic wound, where ultrasound has been shown to stimulate blood flow and reduce swelling.

The device was developed by a team headed by Peter Lewin, the Richard B. Beard distinguished university professor in the School of Biomedical Engineering, Science and Health Systems; and Michael S. Weingarten, professor of surgery and chief of vasular surgery at the College of Medicine and medical director of the Comprehensive Limb Salvage and Wound Healing Program at Drexel; with several faculty affiliated with the School of Biomedical Engineering, Science and Health Systems: Rose Ann DiMaria-Ghalili, professor of nursing in the College of Nursing and Health Professions; Michael Neidrauer, research assistant professor; and Leonid Zubkov, research professor.

In 2013, the researchers tested the device on 20 patients from Weingarten’s wound healing clinic. Applying the ultrasound at a frequency of 20kHz for 15-minute intervals proved to be the most effective combination of energy and duration. All five patients in the group that received this combination of treatment had healed completely by the end of the four-week treatment period. Overall, the study demonstrated that the new treatment improved healing by 15 percent per week.

Based on those results, the National Institutes of Health awarded the team about $3 million to test the therapy on 120 patients over five years, starting in 2017. By using diagnostic monitoring of blood flow in the wound tissue, the clinical trial will also determine how nutrition and inflammation impact wound closure, making treatment customization a possibility.