Odor Sensing Method using Olfactory Receptors and Fluorescent Instrumentation

A sensing system based upon a living body's mechanism is useful to improve the performances of current available artificial sensors especially in terms of their selectivity and sensitivity. This paper presents the fundamental study of odor sensor based on insect olfactory receptors (ORs). Cells expressing ORs are responsible for odor detection. It is possible to monitor the increase in calcium ion concentration using the fluorescent protein inside the cells expressing ORs. In our research we developed an instrumentation system to monitor the fluorescent intensity change for the odor sensing. The system consists of fluidic device, sky blue laser for light excitation, lenses, optical filter, dichroic mirror, and a cooled complementary metal oxide semiconductor (CMOS) camera. Sf21 cells expressing two ORs called OR56a and BmOR3 with their specific response to geosmin and bombykal have been prepared for experiments. Measurement results show that the developed instrumentation was able to detect the odorant with concentration down to 5 mu M for about 15 seconds.