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.