A wireless “smart” bandage that combines advanced electronics with an engineered hydrogel shows promise in accelerating tissue repair by simultaneously monitoring the healing process and treating the wound. Researchers at Stanford University claim in a paper published in Nature Biotechnology on Nov. 24 that the device promotes faster closure of wounds, increases new blood flow to injured tissue, and enhances skin recovery by significantly reducing scar formation.
The smart bandage is composed of wireless circuitry that uses impedance/temperature sensors to monitor the progression of wound healing, explained a news release published on the EurekAlert web site. If healing is stunted or an infection is detected, the sensors send a signal to a central processing unit to apply more electrical stimulation across the wound bed to accelerate tissue closure and reduce infection. The researchers were able to track the sensor data in real time on a smart phone, all without the need for wires, said the news release.
A 100-micron-thick layer of electronics — a microcontroller unit, radio antenna, memory, electrical stimulator, biosensors, and other components — sits atop an engineered hydrogel that is designed to deliver electrical stimulation to heal the injured tissue and collect real-time biosensor data.
The polymer in the hydrogel adheres securely to the wound surface when needed, yet pulls away cleanly and gently without harming the wound when it is warmed a few degrees above body temperature.
“In sealing the wound, the smart bandage protects as it heals,” said Yuanwen Jiang, co-first author of the study and a post-doctoral scholar in the lab of Zhenan Bao, the K.K. Lee Professor in Chemical Engineering at Stanford School of Engineering. “But it is not a passive tool. It is an active healing device that could transform the standard of care in the treatment of chronic wounds.”
Electrical stimulation, also known as galvanotaxis, accelerates the migration of keratinocytes to the wound site, limits bacterial infections, and prevents the development of biofilms on wound surfaces to promote tissue growth and help with tissue repair, said the news release. The Stanford researchers were able to integrate this proven technology with real-time biosensor data to provide what they describe as a novel automated treatment modality informed by biosensors.
The smart bandage senses conductivity and temperature changes in the skin as the wound heals — electrical impedance increases as wounds heal and local temperatures decline as inflammation subsides. “With stimulation and sensing in one device, the smart bandage speeds healing, but it also keeps track as the wound is improving,” said Artem Trotsyuk, also a co-first author of the study who completed his graduate work in the lab of Geoffrey Gurtner, MD, formerly the Johnson & Johnson Distinguished Professor of Surgery (Emeritus) in the Stanford School of Medicine, and currently Chair of the Department of Surgery and Professor of Biomedical Engineering at the University of Arizona in Tucson. “We think it represents a new modality that will enable new biological discovery and the exploration of previously difficult-to-test hypotheses on the human healing process,” added Trotsyuk.
The researchers caution that the smart bandage is, as yet, a proof of concept, albeit a promising one, and that many challenges remain — notably, increasing the size of the device to human scale, reducing cost, and solving long-term data storage issues. Also, new sensors may be added to measure metabolites, biomarkers, and pH, for example. And there are some potential roadblocks to clinical use, such as hydrogel rejection or biofouling of the sensors, which can cause irritation.