This paper reports the application of wavelength modulated differential photothermal radiometry (WM-DPTR) to blood alcohol (ethanol) concentration (BAC) measurements in the mid-infrared range to prevent impaired driving. In-vivo alcohol consumption measurements performed in the BAC range of interest (0-80 mg/dl) with an optimal wavelength pair demonstrated the alcohol detection capability of WM-DPTR with high resolution (~5 mg/dl) and a low detection limit (~10 mg/dl). Oral glucose tolerance tests using both glucose and alcohol sensitive wavelength pairs in the normal-to-hyperglycemia range (~80-320 mg/dl) proved the blood glucose screening ability and ethanol detection specificity of WM-DPTR. The immunity of WM-DPTR to temperature and glucose variation makes the differential signals alcohol sensitive and specific, yielding precise and accurate noninvasive alcohol measurements in the interstitial fluid.
Keywords: (280.1415) Biological sensing and sensors; (300.6380) Modulation spectroscopy; (300.6430) Spectroscopy, photothermal; (350.5340) Photothermal effects.