Advanced Photonic Sensors Based on Interband Cascade Lasers for Real-Time Mouse Breath Analysis

A multiparameter gas sensor based on distributed feedback interband cascade lasers emitting at 4.35 mu m and ultrafast electro-spun luminescence oxygen sensors has been developed for the quantification and continuous monitoring of (CO2)-C-13/(CO2)-C-12 isotopic ratio changes and oxygen in exhaled mouse breath samples. Mid-infrared absorption spectra for quantitatively monitoring the enrichment of (CO2)-C-13 levels were recorded in a miniaturized dual-channel substrate-integrated hollow waveguide using balanced ratiometric detection, whereas luminescence quenching was used for synchronously detecting exhaled oxygen levels. Allan variance analysis verified a CO2 measurement precision of 1.6 parts per thousand during a 480 s integration time. Routine online monitoring of exhaled mouse breath was performed in 14 mechanically ventilated and instrumented mice and demonstrated the feasibility of online isotope-selective exhaled breath analysis within microliters of probed gas samples using the reported combined sensor platform.