Chronic skin wounds may be notoriously difficult to treat, but at the same time they shouldn't be over-treated, subjecting patients to more antibiotics than is necessary. That's why scientists have developed a "smart" bandage that only dispenses medication as needed.

Developed by a research team at Massachusetts' Tufts University, the prototype bandage is just 3 mm thick, and consists of transparent medical tape, a heat-activated antibiotic gel, and flexible electronic components.

One of those components is a sensor that measures the pH value of the wound – if the figure is significantly above 6.5, it indicates that the wound is infected. The bandage also contains a temperature sensor, which detects the heat associated with inflammation. Additionally, the scientists have developed sensors that could be added to measure oxygenation, which is a sign of healing.

An integrated microprocessor analyzes the readings from the sensors, to gauge how the wound is doing. If infection and/or inflammation are detected, the processor responds by temporarily activating heating elements that are built into the bandage. This raises the temperature of the gel, causing it to release more antibiotics into the wound.

Most of the components are relatively inexpensive, and would simply be discarded when the bandage was removed. One exception is the microprocessor, which could be disinfected and reused.

Pre-clinical trials of the technology are now underway.

"The smart bandage we created, with pH and temperature sensors and antibiotic drug delivery, is really a prototype for a wide range of possibilities," said Prof. Sameer Sonkusale, corresponding co-author of a paper on the study. "One can imagine embedding other sensing components, drugs, and growth factors that treat different conditions in response to different healing markers."

The paper was published this Friday in the journal Small.

Another team is working on a different smart bandage that delivers antibiotics to chronic wounds on a preset schedule, and that could conceivably dispense medication in response to readings from onboard sensors.