Real-time monitoring of moist wound healing by a flexible adaptive impedance sensing patch

Moist wound healing has been recommended by the U.S. Food and Drug Administration (FDA) as a preferred approach for skin wound treatment. The global market for moist wound dressings is valued at approximately USD 4.83 billion, driven by the ability of moist wound environments to promote faster healing, improve recovery quality, and reduce pain. Covering the wound with dressings, mostly hydrocolloid-based, is a preferred method to maintain a moist wound environment and isolate this environment from external interferences. Currently, commercial hydrocolloid dressings have already reached satisfactory performance, including efficient exudate absorption, good bacterial control, and low cost. Meanwhile, these commercial hydrocolloid dressings are opaque or will become opaque after absorbing liquid, hindering the direct observation of the wound. Under such circumstances, possible infections or unsatisfactory wound recovery cannot be discovered in time and may deteriorate the wound. To address this issue, this study presents a simple, wireless, and lightweight (3.2 g) impedance sensor for monitoring wound healing status under commercial hydrocolloid dressings. The specially designed spiral parallel electrodes realize accurate impedance measuring and, more importantly, adapt to the gradually contracting wound site. The adaptive moist wound sensing patch (AMoW-SP) substrate provides both high flexibility to adapt to the skin profile and good biocompatibility for not interfering with the wound recovery. The compact wireless communication and power circuit enables visual readout of the wound recovery status on a smartphone and therefore maintains the point-of-care nature of hydrocolloid-dressing-based moist healing. Mouse experiments demonstrate that the AMoW-SP is capable of accurately monitoring normal and chronic wounds for 24 days.