Fig. 6. Response of the handheld alcohol breath analyzer to ethanol exposure.

a Sensor signal while exposing the NDIR sensing system to different ethanol concentrations in a controlled environment, confirming that the emitted radiation intensity in the wavelength range of ≈9.5 µm of IR emitter is sufficient for the detection of ethanol. The sensor system showed signal drops of 6.5 %, 11.5 % and 16 % for ethanol concentrations of 200 ppm, 353 ppm and 502 ppm, respectively. b Measured ethanol and CO₂ sensor signals when a sober proband is exhaled into the sensor system. A significant dip of the carbon dioxide detector signal verifies the exhalation of the proband, while the sensor signal of the ethanol detector remains virtually constant. c Measured ethanol and CO₂ sensor signals when a proband with elevated breath alcohol concentration is exhaled on the sensor. Both the ethanol and carbon dioxide signals decrease significantly, thereby confirming that the NDIR sensor system is sufficiently sensitive to detect elevated breath alcohol concentration levels