A new flexible sensor developed by a joint research team from Pennsylvania State University and Hebei University of Technology in China could revolutionize the way wound healing is tracked. The sensor can accurately measure temperature and physical strain simultaneously and separately, providing unprecedented precision for healthcare monitoring.

"This unique sensor material has great potential for use in health care monitoring," said Huanyu "Larry" Cheng, Memorial Associate Professor of Engineering Science and Mechanics, Penn State and co-corresponding author of the study. "By precisely measuring temperature changes and physical deformation during wound healing, it can provide doctors with a clearer picture of the healing progress and help detect problems such as inflammation earlier."

The researchers developed the sensor using laser-induced graphene (LIG), a two-dimensional material with unique thermoelectric properties that convert temperature differences into voltage, enabling independent measurement of temperature and strain signals. The porous structure of the material allows it to integrate closely with human soft tissue while maintaining high flexibility and sensitivity.

"When a material is sensitive to both temperature and strain, it can be difficult to distinguish the source of the signal," Cheng explained. "But by exploiting the thermoelectric effect of LIG, we can decouple these two measurements. We can look at the resistance to get the strain information, and measure the thermovoltage to determine the temperature, allowing for precise monitoring of the wound site."

Not only can the sensor detect temperature changes as small as 0.5 degrees Celsius, but it can also maintain functionality when stretched up to 45%, adapting to different shapes and surfaces. In addition, LIG's thermoelectric properties make it self-powered and can operate continuously without the need for an external power source.

"The material's porous structure creates many tiny spaces and channels that allow it to interact with its surroundings in a highly sensitive manner," Cheng said. "This makes it ideal for use in soft human tissue, in stark contrast to traditional rigid thermoelectric materials."

To further improve practicality, the research team has also developed a wireless system that allows users to remotely monitor sensor data in real-time via a smartphone or other device. This means that doctors can remotely monitor the healing of patients' wounds, and emergency responders can receive timely alerts of dangerous temperature changes.

"These advances are designed to make the technology easier to use and more effective, helping to improve health monitoring and safety in everyday situations," Cheng said.

The research, published in the journal Nature Communications (DOI: 10.1038/s41467-024-55790-x) and supported by the National Institutes of Health and the National Science Foundation, not only revolutionizes wound healing monitoring but also opens up new possibilities for the development of future wearable medical devices.