Moisture is an important parameter in wound healing. An optimal moist environment assists cell migration and increases wound healing. Therefore, wound moisture levels require continuous monitoring.
Conventional wound dressings like cotton bandages cannot give real time feedback on the condition of the wound. To determine the condition of the wound, bandages have to be periodically removed, causing the patient pain and discomfort.
So, researchers at the Velammal College of Engineering and Technology, Madurai, and the Dr Sivanthi Aditanar College of Engineering, Tiruchendur, recently developed a smart dressing that can monitor moisture levels of wounds.
They chose bamboo, banana, and pineapple fibres instead of cotton fibres and stacked mats made of these fibres one top of the other. Each fibre layer had a different structural strength, and moisture absorption and dielectric properties. Dielectric properties play a crucial role in determining the performance of the antenna that works as a moisture aware dressing.
To design the best order of stacking for the three different fibres, the researchers evaluated the morphology of the fibre mats, which determines their response to moisture, and the dielectric properties, which determine their performance in the antenna.
Bamboo fibre had a high dielectric constant and low dielectric loss. Its dense morphology and interlocked fibrillar structure provide mechanical stability and stable dielectric properties, making it suitable for the outermost layer of the antenna structure.
The pineapple mat had a porous morphology and lower dielectric constant. So it was chosen for the innermost layer in contact with the skin where it acted as a moisture permeable, breathable layer.
The banana fibre, predominantly composed of cellulose and hemicellulose, had moderate dielectric loss suitable for the intermediate layer of the bandage.
The researchers glued the three layers together using polyvinyl acetate and filled the gaps between the layers with talcum to eliminate any air pores that would alter the dielectric response of their antenna.
An antenna needs a radiating patch, a resonant conductive element that converts electromagnetic signals from the feed into radiated frequency waves. It also needs a zero-potential or reference plane that acts as the return path for high-frequency currents flowing from the feed and patch.
The researchers used thin copper plates for the ground structure and the radiating patch. The three layers of mats were sandwiched between the ground structure that would be in contact with the wound and the radiating patch of the antenna.
To optimise the structures of the ground plate and the radiating patch, the researchers used the ANSYS high-frequency structure simulator, software that uses the finite element method for analysing the electromagnetic performance of the antenna. After protracted and reiterative testing of possibilities, the researchers found the best design for the ground structure and the radiating patch to emit a resonance frequency of 2.45 gigaHertz, the optimum band for for industrial, scientific and medical uses. The best design for the ground structure had a number of circular holes, while the one for the radiating patch had two tick marks etched on it.
The researchers then assessed the safety and compatibility of the device by placing a multilayer human hand model near it. They measured the absorption rate of electromagnetic radiation by the human hand model and compared it against standard exposure limits. The absorption rate met the internationally accepted exposure limits, making the dressing that doubles up as an antenna safe to use on the human body.
The researchers evaluated the moisture sensitivity of the bandage by testing the dielectric properties of the three fibre layers under low-moisture and high-moisture wound conditions. The dielectric properties of the three fibre layers increased with increase in moisture content. The relative permittivity increased with increasing moisture content. Pineapple fibre exhibited the greatest increase, followed by banana and bamboo.
These changes in dielectric properties enable the antenna to detect moisture-related changes in the wound dressing allowing the smart wound bandage to monitor wound moisture levels and provide useful information about wound conditions and the healing process.
Now that the design and development is done, the moisture aware antenna incorporated wound dressing is ready to be evaluated on wound models in mice or rats.
Journal of Materials Science: Materials in Electronics, 37: 25 (2026);
DOI: 10.1007/s10854-026-18329-y
Reported by Deepika Baskaran
SASTRA Deemed University, Thanjavur
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