An electronic
system and method for detecting analytes, such as
carbon dioxide, is provided, using an improved
nanostructure sensor (CO2 sensor). The CO2 sensor may comprise a substrate and a
nanostructure, such as a one or more carbon nanotubes disposed over the substrate (e.g., as a network). One or more conductive elements may electrically communicate with the
nanostructure. A counter or gate
electrode may be positioned adjacent the nanostructure. A functionalization material reactive with
carbon dioxide may be included, either disposed in contact with the nanostructure or isolated by a
dielectric. The sensor may be connected to a circuit responsive to changes in CO2 concentration in the environment. Embodiments are described of medical sensing systems including one or more CO2 sensors. One embodiment comprises a
breath sampling cannula which is connected to a sensor unit. In an alternative, the cannula permits
supplemental oxygen to be administered, while recovering and measuring analytes in breath samples. The cannula may connect to a portable processor-display unit for monitoring one or more analytes, such as CO2. Another embodiment includes a cannula configured for the monitoring of sleep disorders, such as
apnea, comprising one or more sensors disposed adjacent a
breath sampling channel, optionally including flow rate or other sensors. The sensors may be connected by wired or
wireless links for to a processor / input / display unit. Any of the embodiments may include filters, selectively permeable membranes, absorbents, and the like to
precondition the breath sample, may be configured to include complementary
chemistry measurements.