| 摘要 |
A gas or vapour detector (1) with a chemiresistor array (10) has an inlet (11) connected to the outlet of a mixer (4). The mixer (4) has one inlet (5) exposed to a gas or vapour sample containing an analyte. The second inlet (7) of the mixer is connected to a source (8) of a reference gas or vapour free from the analyte. The second inlet (7) is normally closed so that the detector (1) is supplied exclusively with gas from the inlet (5). When the detector (1) detects an analyte present at a concentration above a threshold level it sends a control output via line (3) to the mixer (4). This signal causes the mixer (4) to open the second inlet (7) progressively, gradually to admit more of the reference gas or vapour so that the mixture supplied to the detector gradually becomes less concentrated with the analyte until it falls below the detection threshold and can no longer be detected. The concentration of the sample and reference gas mixture at which the threshold is passed is compared with information obtained during set up of the detector so that an indication can be provided of the concentration of the analyte in the sample. A method using the detector can be the analysis of breath indicative of the presence of a disease of a patient. |
