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A tiny electrode fuels smart bandage technology

Band-aid technology has made incremental improvements in the years since its commercial introduction in the late 1960s, the most important of which has been the incorporation of antibiotics into the nonadhesive padding. But imagine if adhesive bandages could do more than passively prevent the growth of bacteria — imagine if they could monitor a wound and predict that growth.

DiPietro assistant professor of chemical engineering Edgar Goluch has developed an electrochemical sensor that could some day make these so-called “smart bandages” a reality.

Bacteria produce a host of compounds, he said, some of which are electrochemically active. Goluch’s device, which he developed with the help of graduate student Thaddaeus Webster, works by detecting these charged molecules.

Similar devices have been developed in the past, Goluch noted, but they were all hindered by a single component that could not be miniaturized to enable the smart-bandage idea. Electrochemical sensors need at least two things to work: a reference and a working electrode. Most of the microscale devices previously developed used macroscale reference electrodes; otherwise, they were unstable in complex chemical environments.

Each gold line represents a separate electrochemical device capable of detecting microscope bacteria at very low concentrations. Photo by Edgar Goluch.

In a paper published in the journal Lab on a Chip, Goluch and Webster detail the inner workings of a stable, microscale reference electrode, which they used to detect the presence of a compound called pyocyanin that can be found only in the bacteria Pseudomonas aeruginosa.

Goluch said P. aeruginosa is an old, prehistoric organism. As he put it, “It can survive under extremely harsh conditions.”

The organism is present just about everywhere and normally that would not be a problem because it doesn’t make healthy people sick. But for patients with compromised immune systems, these bacteria are deadly.

“We want to be able to detect the bacteria before a biofilm forms,” Goluch explained, adding that his interdisciplinary background, which includes graduate degrees in mechanical engineering and bioengineering, gave him the expertise to develop this unique sensing system. “Early detection of infection and contamination greatly improves a patient’s chances of survival.”

His device can do exactly that.

The new reference electrode is made of palladium, which is capable of storing more than 900 times its volume in hydrogen, making it an extremely stable reference. The material has previously been used as a pH detector for its storage capabilities.

The project’s key breakthrough lies is palladium’s ease of use and ability to be shaped into miniature wires, making it an ideal material to incorporate into microscale sensors.