A wirelessly-powered smart bandage developed by French and UK researchers could help patients with non-healing wounds avoid infections.

The bandage could help improve the quality of life of people who live with chronic non-healing wounds, which frequently require painful cleaning and treatment. Non-healing wounds can be a side effect of certain medications or health factors such as diabetes, cancer or damaged blood vessels.

The researchers embedded the bandage with LEDs to bathe wounds in sterilising ultraviolet light, preventing the growth of bacteria without the use of drugs such as antibiotics. UV light is already widely used to sterilise objects such as surgical equipment and fresh food. Treating bacterial infections in non-healing wounds with UV light instead of drugs could help slow the rise of dangerous new strains of antibiotic-resistant bacteria known as superbugs.

In a paper published in IEEE Transactions on Biomedical Circuits & Systems, the researchers outline how they built the smart bandage and demonstrated its antibacterial effectiveness.

They built a slim, flexible inductive coil that could be integrated into the fabric of the bandage. The coil uses magnetic-resonant wireless power transfer to provide power to the UV LEDs without the need for batteries. Instead, the inductive coil receives its power over the air, transmitted from a second coil connected to the electrical mains. The LEDs can be powered indefinitely simply by keeping the transmitting and receiving coils close to one another until the antimicrobial treatment is complete.

In lab tests, the researchers exposed samples of a strain of gram-negative bacteria called pseudoalteromonas sp D41 to the UV light supplied by the smart bandage. Some forms of gram-negative bacteria can cause a range of serious infections in humans.

The tests showed that the smart bandage could slow and stop the growth of pseudoalteromonas sp D41 on the surfaces of slides, effectively eradicating the bacteria within six hours. The researchers suggest the system could find use in medical settings to do the same for bacteria in patients’ chronic non-healing wounds.

“The use of ultraviolet light to kill viruses and bacteria is well known and this is the first work to integrate UVC emitting LEDs within a bandage and explore its efficacy,” said Steve Beeby, chair in emerging technologies at the University of Southampton and a co-author of the paper. “This approach could provide a significant benefit to the treatment of persistent wounds and is a major advance over typical smart bandages that attempt to monitor wound condition.”

Mahmoud Wagih of the University of Glasgow’s James Watt School of Engineering is another co-author of the paper. He developed the smart bandage’s wireless power delivery system.

“Traditional batteries are bulky, inflexible, and need to be changed regularly,” said Wagih. “That makes them difficult to use in bandages, which need to conform closely to the contours of patients’ bodies to deliver reliable treatment over several hours. The system we’ve developed is flexible and can be seamlessly integrated into the fabric of a bandage to power the LEDs, which deliver UV-C light across any surface.”

He said he believed smart bandages would be key to future healthcare, but there was a need to be mindful of their environmental footprint.

“In the UK alone, over 40,000 tonnes of batteries are sold annually and less than half of them are recycled,” he said. “Our wireless power technology will allow healthcare wearables to grow, sustainably, as an alternative to drug-based treatments. We’ll be continuing to collaborate on developing the bandage further to integrate sensors capable of monitoring the progress of wounds, as well as setting out to test the technology in clinical settings in the years to come.”

The smart bandage is built on technology initially developed by Wagih and his colleagues from the University of Southampton. The research is showcased in a second paper, recently published in IEEE Transactions on Industrial Electronics. The paper demonstrates the first use of magnetic-resonant wireless power transfer to provide electricity to standard textiles using embroidery or screen printing, a feature that helped make the smart bandage possible.

In this case, the power was supplied to a newly-developed flexible electronic resistor made from silver and carbon. This was printed into a textile surface to act as a wearable heating element. The system was capable of being heated to up to 60˚C while separated from the transmitter by 2cm at an efficiency exceeding 50%.

“Heaters are very power-intensive, so battery-powered heaters tend to either chew through batteries very quickly or provide only a moderate amount of heat for a bit longer before a change is required,” Wagih said. “This paper shows how high-frequency magnetic-resonant wireless power transfer can be used to power an efficient heating system built into clothing which can be washed and reused, which is impossible with conventional batteries.”

The efficiency of power delivery is said to be twice that of previous wearable wireless power receivers developed elsewhere. Given the importance of energy-efficient heating, this opens up possibilities for use in medical applications, heated clothing which could be worn in cold conditions, and more, said Wagih.

The smart bandage paper was published in IEEE Transactions on Biomedical Circuits & Systems.

Researchers from the universities of Southampton and Glasgow in the UK contributed to the paper, along with colleagues from the Detection, Sensors & Measurements Laboratory at Infremer in France.