Abstract: The invention exploits the evolutionary principles responsible for the development of the broad spectrum general odorant detector system, to create a cell-surface receptor based system capable of detecting and discriminating between thousands of chemicals. This is accomplished by subjecting a defined set of cell-surface receptors such as G-protein coupled receptors, tyrosine kinase receptors, and/or ion channels, to the types of evolutionary forces that have created the array of approximately 1,000 natural receptors used in general olfaction by higher animals. This goal is further accomplished by a ‘directed evolution-in-a-test-tube’ method, imposing very high rates of mutation and extremely strict selection criteria to create a sensor. The novel sensor of the present invention is selected using a sensitive melanophore-based functional bioassay.