Lock-in measurement technique in fluorescent instrumentation system for cell-based odor sensor

A fluorescent instrumentation system is widely used for cell-based odor sensors. However, the fluorescent instrumentation system was easily affected by ambient light. The measurement is limited if dark conditions are required for the measurement. This paper presents the design and implementation of a lock-in measurement technique in a fluorescent instrumentation system for a cell-based odor sensor. A continuous mode of laser diode excitation was changed to a pulse mode for the purpose of modulating the fluorescent light. The ambient light asynchronous with the modulated fluorescent light can be eliminated even if the ambient light level is much higher than that of the fluorescent light. Experimental results show that using the lock-in measurement technique, the weak fluorescent signal can be extracted from a modulated signal buried under noise. We conclude that the developed fluorescent measurement system can be used to observe the concentration dependency of odorant even under ambient light conditions.