According to one aspect of the invention, the apparatus comprises a fluid collecting device configured to receive a sample of breath； a conditioning device coupled to the fluid collecting device and configured to receive the sample of breath and condition the sample with respect to at least one of temperature, flow rate, pressure, humidity, and concentration； and a sensing device coupled to the conditioning device and configured to receive the conditioned sample, wherein the sensing device includes a nanoparticle-based sensor and further whereby the analyte interacts with the sensing device to cause a change that is sensed by the sensing device and wherein the change comprises information useful in characterizing the analyte. Preferably, the apparatus is hand-held and characterizing the analyte is useful for health monitoring.
