Non-contact alcohol detection in mice using an imaging photoplethysmography (IPPG) system

We report on a method to determine whether alcohol has been consumed using camera-based, non-contact imaging photoplethysmography (IPPG) technology. IPPG signals were collected using a visible-band CMOS camera and a 520 nm light-emitting diode (LED). The light source was set to a uniform light output of 2.8 mW/cm², and images were captured at 150 frames per second. To compare signal changes before and after alcohol consumption, hairless mice were orally administered alcohol, and IPPG signals were collected hourly. Signal analysis assessed alcohol consumption over time using frequency components of respiration and heart rate, second-harmonic components, and the frequency-to-magnitude ratio. Furthermore, alcohol consumption was assessed by analyzing the magnitude ratio and scatter plot at various frequencies, and the system's validity was confirmed through repeated experiments. These results clearly demonstrate that non-contact IPPG technology can be used as an effective and reliable tool for detecting alcohol consumption.