It can take an inventor years to receive an official U.S. patent, usually represented by a seven-digit number. But the full story behind most patents is much longer. Peter A. Lewin and Michael S. Weingarten’s specially designed ultrasound device for treating chronic wounds has an application pending to become one of nearly 300 patents issued to Drexel faculty, and this is the story of how it came to be.
When most people think of “ultrasound,” they think babies.
For Peter A. Lewin, the Richard B. Beard distinguished university professor in the School of Biomedical Engineering, Science and Health Systems and director of the Biomedical Ultrasound Research and Education Center, the word conjures up a different creation: A device born at Drexel that uses sound waves to help venous ulcers and diabetic wounds heal.
The healing power of ultrasound is well known. By directing “ultrasonic” sound waves toward a part of the body at a certain frequency, ultrasound can increase blood flow and reduce swelling in athletes’ muscle and ligament injuries, for instance.
But for reasons that aren’t well understood, that frequency — 1 to 3 megahertz — is not necessarily optimal to help wounds that don’t heal in a predictable and timely way.
Lewin knew that the higher the frequency, the higher the loss of the energy in the tissue. Maybe, he thought, the wounds and the underlying tissue aren’t receiving enough energy, and an ultrasound device that operated at lower frequencies could cover and penetrate the chronic wound better.
The problem was how to design a truly portable, lightweight ultrasound device that dispenses frequency of less than 100 or even 50 kilohertz. It was even harder for Lewin, an electrical engineer, to access patients with chronic wounds to test his device on.
Then about six years ago, he met Michael S. Weingarten, professor of surgery in the College of Medicine. As Director of the Comprehensive Wound Healing Program, Weingarten treats over 500 patients a year, with most patients suffering from common chronic wounds like venous ulcers.
Affecting more than 500,000 people each year, venous ulcers result from a malfunctioning valve in a vein that allows blood to flow backward, causing varicose veins, discoloration and painful swelling. These kinds of wounds can take months and years to heal, at great personal expense — standard treatment costs as much as $2,400 a month.
“We had patients with problems, and Dr. Lewin had great ideas to make gizmos to help them,” says Weingarten.
With Lewin as the principal investigator and Weingarten as the principal clinical investigator, the team tested the device on 20 patients. They knew they were onto something when the tests showed that yes, the ultrasound therapy did work using a lower frequency — 20 kilohertz instead of megahertz — and required a shorter period of exposure — 15 minutes instead of 45.
With those results in hand, in 2015 Lewin and Weingarten filed for a patent on their baby: A lightweight, battery-powered and fully wearable ultrasound device for chronic wound treatment.
