Smart Bandage

It is estimated that pressure ulcers (bed sores) affect 2.5 million people annually in the United States alone, adding an $11 billion burden to an already strained healthcare system. Because they’re associated with dangerous and deadly septic infections, they put hospital patients at a nearly three times risk of death, and the incidence of bed sores is on the rise due to the growing prevalence of obesity and diabetes.

But recent advances in flexible electronics have led to the development of a “smart bandage” that can detect tissue damage in its early stages, while it may still be reversible. The technology is based on the fact that electrical changes occur in cells when they die off. Dozens of electrodes are printed in an array on a thin, flexible substrate and a small current is applied between electrodes. Using a technique known as impedance spectroscopy, a map of the underlying tissue is created based on the flow of current at different frequencies. When a cell is healthy, the cell membrane acts like an insulator and the impedance is high. But, as the cell walls begin to break down, they allow current to flow more readily.

The device was tested on rats where pressure wounds were mimicked by squeezing the bare skin between magnets for one to three hours. When the magnets were removed, the accelerated cell death caused by oxidative damage and inflammation was measured using the bandage. Quantifiable changes in the electrical resistance were evident, with milder injury (one hour of pressure) showing signs of reversal after several days, and more severe injury (three hours of pressure) producing more serious, permanent damage.

The technology could be incorporated into wound dressings or designed as a spot-check device for clinicians to monitor targeted areas of the body.