SmoColi is a bacterio-quantifier of acetaldehyde concentration that can be used as a passive smoke detector. Acetaldehyde is a toxic and carcinogenic component of cigarette smoke. It has a boiling point of 20.2 °C and is very volatile, thus can be used as an information carrier through air. The SmoColi cells are immobilized in an agarose coated microfluidic device. The test solution is fed on one end of a microfluidic channel, in which an acetaldehyde gradient is established by synthetic cellular degradation. The cells are engineered to sense acetaldehyde by a synthetically re-designed fungal acetaldehyde-responsive transactivator. The sensor is linked to a band pass filter that drives GFP expression. This allows establishment of an input concentration-dependent, spatially located fluorescent band displaying quantitative information about acetaldehyde. Finally, if the acetaldehyde concentration exceeds the threshold of malignance, the whole device turns red through a quorum-sensing-based mCherry alarm system, turning the whole device red.
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