“Smart” Bandage Glows When Healing Occurs

An oxygen-sensing porphyrin-dendrimer with a long phosphorescence lifetime and dynamic range is integrated with the liquid bandage matrix, which conforms to the skin’s surface to form an airtight seal. An imaging device quantifies and maps both the pO2 and oxygen consumption of the underlying tissue.

The bandage is applied by painting it onto the skin’s surface as a viscous liquid, which dries to a solid thin film within one minute. Once the first layer has dried, a transparent barrier layer is then applied to protect the film and slow the rate of oxygen exchange between the bandage and room air, thus making the bandage only sensitive to the oxygen within tissue. The imaging device then provides a burst of excitation light that triggers the emission of the phosphors inside the bandage, and records the phosphors’ emission. The study describing the bandage was published in the November 2014 issue of Biomedical Optics Express.

“Depending on the camera’s configuration, we can measure either the brightness or color of the emitted light across the bandage, or the change in brightness over time,” said lead author Zongxi Li, PhD, of the MGH Wellman Center for Photomedicine. “Both of these signals can be used to create an oxygenation map. The emitted light from the bandage is bright enough that it can be acquired using a regular camera or smartphone, opening the possibility to a portable, field-ready device.”

“The need for a reliable, accurate and easy-to-use method of rapid assessment of blood flow to the skin for patients remains a clinical necessity,” said study coauthor Samuel Lin, MD, an associate professor of surgery at HMS. “Plastic surgeons continuously monitor the state of blood flow to the skin, so the liquid-bandage oxygenation sensor is an exciting step toward improving patient care within the realm of vascular blood flow examination of the skin.”

Oxygen plays an important role in wound healing, as it is essential to biological functions such as cell proliferation, immune responses, and collagen synthesis. Poor oxygenation is directly associated with the development of chronic ischemic wounds, which affect more than 6 million people each year in the United States alone. Knowledge of oxygenation status is also important for management of burns and skin grafts, as well as in a wide range of skin conditions.

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