Microfluidic device for airborne BTEX detection

We fabricated a microfluidic device for the optical detection of airborne b enzene, toluene, ethylbenzene and xylenes (BTEX). The device consists of co ncentration and detection cells formed of 3 cm x 1 cm Pyrex plates. The con centration cell is composed of an adsorbent to concentrate the BTEX gases a nd a thin-film heater to desorb the concentrated gases from the adsorbent t hermally. The collected gases are introduced into the detection cell, which is connected to optical fibers, to measure their absorption spectra. We op timized the device's operating conditions by studying the thermal character istics of the concentration cell and the time profile of the gas concentrat ion flowing in the detection cell. We used the device under optimized opera ting conditions to detect toluene gas as a typical example BTEX. The gas co ncentration amplification rate was similar to2 orders of magnitude, and we successfully measured parts-per-million levels of toluene gas with this dev ice.