A wireless strain sensor for wound monitoring with direct laser-defined patterning on a commercial dressing

Controlled mechanical strain or stress on a wound site can promote accelerated neovascularization and cellular proliferation for improved wound healing; however, these mechanical forces have not been properly quantified due to a lack of standardized technique. As a solution, we developed a wireless strain sensor on a commercial wound dressing. The sensor consists of a flexible antenna coil whose resonant frequency changes in response to applied strain. The frequency change of the sensor is observed to be a linear function of applied strain in the range of 0-35%, with an average sensitivity of 150 kHz/%strain and negligible hysteresis. The sensor is fabricated through a simple process that consist of defining a screen-printing mask directly over the wound dressing using laser machining. The fabrication technique can be scaled up for mass production using roll-to-roll methods