Highly accurate breath test system

Abstract

The invention relates to a system for breath test of a person. It includes a sensor unit configured to sense the presence/concentration of a volatile substance, e.g. alcohol, present in air flowing through a predefined inlet area and generating a signal corresponding to the concentration of said substance. An analyzer determines the concentration of said substance in the breath of said person. It comprises means for the temporary interruption of said air flow at a point in time coinciding with the detection of a breath. It also relates to a method comprising interrupting the flow through said predefined area for a predetermined period of time, and detecting the concentration of said substance during said interruption.

1 . A system for breath test of a person including
 a sensor unit ( 5 ) comprising
 a first sensor element ( 8 ) configured to detect the presence and/or concentration of a volatile substance, present in air from a breath flowing through a predefined inlet area ( 4 ) and to generate a signal corresponding to the concentration of said substance; 
 a second sensor element ( 7 ) configured to detect the presence of a tracer gas in said flowing air; 
   an analyzer ( 10 ) configured to determine the concentration of said substance in the breath of said person, the determination being based on said signal corresponding to the substance concentration;   means for generating and controlling said air flow ( 10 ,  12 ,  14 ), including a fan or a pump ( 9 ), said means being adapted to interrupt said flow upon the detection of a breath, wherein the criteria for breath detection includes tracer gas detection.   
     
     
         2 .- 15 . (canceled)