Abstract: A system is provided that includes a portable measurement device for measuring acetone in a breath sample of a user. The measurement device comprises a housing, a user-direct breath input device for engaging in direct fluid communication with a respiratory tract of the user and receiving the breath sample from the respiratory tract, a flow path disposed within the housing, a nanoparticle-based sensor disposed in the housing in fluid communication with the flow path and at an intermediate location between the upstream end and the downstream end, and a flow control device disposed in the housing and in the flow path between the upstream end and the nanoparticle-based sensor that prevents flow of the breath sample in an upstream direction opposite the downstream direction.

Abstract: A disposable cartridge is provided for indicating the concentration of an analyte of interest in breath. The cartridge includes a housing having a side wall and a longitudinal axis, a reaction chamber in the housing, an optically transparent window in the side wall, for viewing contents of the reaction chamber, the window having a height measured in the direction of the longitudinal axis, and a liquid chamber in the housing. The cartridge is configured to display a color that extends along the entire height of the window following the transfer of liquid from the liquid chamber into the reaction chamber. The intensity of the color corresponds to a concentration of the analyte of interest in the reaction chamber.

Abstract: An analyzer is provided for sensing an analyte in breath of a patient. The analyzer includes a base, a breath input port on the base for removable coupling to a source of breath, a cartridge receiving cavity on the base for removably receiving a disposable cartridge having an optically transparent window and a reaction volume, a flow path in the base configured to place the breath input port into communication with the reaction volume when the cartridge is installed in the cartridge receiving cavity, an optical subsystem in the base that senses an optical change in the reaction volume through the window, and a pump in the base configured to pump breath from the source of breath to the reaction volume during a measurement cycle when the source of breath is coupled to the breath input port, and to pump atmospheric air through the flow path during a flush cycle.

Abstract: A method of determining the concentration of an analyte of interest in breath. The method includes obtaining a disposable cartridge comprising a reaction chamber, a liquid chamber, and a window to permit determination of a color intensity in the reaction chamber, directing a volume of breath into the cartridge, and initiating a sequence whereby liquid is released from the liquid container into the reaction chamber to cause a reaction which produces a change in the intensity of a color viewable through the window. The intensity of the color corresponds to the concentration of the analyte of interest. The reaction progresses through a kinetic phase and eventually reaches equilibrium. The sequence additionally includes measuring the intensity of the color at a point in the kinetic phase, to determine the concentration of the analyte of interest in breath.