The present invention relates to a biomimetic sensor for detecting the presence of airborne toxins, such as carbon monoxide, mercury, ethylene oxide, volatile organic materials, and hydrogen sulfide. The biomimetic sensor, which has a functional life of at least one year, comprises a porous, semi-transparent substrate into which is impregnated a self-regenerating chemical sensor reagent. The response of the biomimetic sensor mimics the human response to such toxins, with respect to sensitivity and affinity. The extended functional lifetime of the biomimetic sensor and the mimicking of the human response to the toxins are achieved by the use of a molecular encapsulant that encapsulates at least one component of the chemical sensor reagent.