Measurement of alcohol gas with low concentration in porous silicon sensors by UV light

Capacitance-type alcohol gas sensors using porous silicon (PS) layer as sensitive film were fabricated to measure low alcohol gas concentration. Though sensors using PS layer have shown high sensitivity by large internal surface area, there is still much room for improvement to measure low breath alcohol concentration especially at room temperature. In this work, we measured the variation of the capacitance for the range of 0 to 0.5% alcohol concentration from the proposed sensors, and observed how to affect the sensitivity by illumination of UV light. In addition, the effect of CO₂ and N₂ gases involved commonly in exhaling breath was estimated, and the same experiment against methanol vapor was executed to compare qualitatively with alcohol vapor