Innovative design for optical porous silicon gas sensor

LEANDRO N. ACQUAROLI; RAÚL URTEAGA; R.R. KOROPECKI

SENSORS AND ACTUATORS B-CHEMICAL

ELSEVIER SCIENCE SA

Año: 2010 vol. 149 p. 189 - 193

0925-4005

A simple system for the detection of analytes in the atmosphere employing a freestanding nanostructuredporous silicon optical microcavity was designed and built. The system is based on the measurement ofoptical transmittance changes as a function of the incidence angle of a monochromatic laser beam. Usinga matrix formalism and effective medium theories we calculate the optimal conditions for the system soas to obtain the best sensitivity of the sensor. We tested the system over a detection area of the poroussilicon microcavity of 100m2 with isopropyl alcohol vapor diluted in a N2 stream. With the systemproposed we were able to detect changes in the concentration of isopropyl alcohol as small as 1 ppm,which is equivalent to a change in the effective refractive index of about 3×10−6. The response time isvery fast, lower than 0.5 s.