Capacitive porous silicon sensors for measurement of low alcohol gas concentration at room temperature

Capacitive alcohol gas sensors using a porous silicon (PS) layer were fabri cated and investigated for the measurement of breath alcohol concentration. Since the PS layer shows high adsorption against ethanol along with a larg e internal surface area, detecting low alcohol gas concentrations without a ny heating may be realized in comparison with metal oxide sensors. In this work, we measured the capacitance for the range of 0-0.5% alcohol concentra tions using the proposed sensors, and observed how illumination of UV light affected the sensitivity. In addition, the effect of CO2 and N-2 gases inv olved commonly in exhaling breath was estimated, and the same experiment fo r methanol gas was executed to compare qualitatively with ethanol gas.