A non-contact wearable device for monitoring epidermal molecular flux

All existing wearable technologies rely on physical coupling to the body to establish optical, fluidic, thermal, and/or mechanical measurement interfaces. Here, we present a class of wearable device platform that relies instead on physical decoupling, to define an enclosed chamber immediately adjacent to the surface of the skin. Streams of vaporised molecular substances that pass out of or into the skin alter the properties of the microclimate defined within this chamber in ways that can be precisely quantified using an integrated collection of wireless sensors. A programmable, bistable valve dynamically controls access to the surrounding ambient, thereby creating a transient response that can be quantitatively related to the inward and outward flux of targeted species through analysis of the time dependent readings from the sensors. The systems reported here offer unique capabilities in measuring the flux of water vapour, volatile organic compounds (VOCs), and carbon dioxide from various locations on the body, each with distinct relevance to clinical care and/or exposure to hazardous vapours. Studies of healing processes associated with dermal wounds in normal and diabetic animal models and of responses in infected wound models reveal characteristic variations in flux that provide important insights, as use cases where the non-contact operation of the devices avoids potential damage to fragile tissues.