Two-Dimensional Digital Lock-In Circuit for Fluorescent Imaging of Odor Biosensor System

In the field of life science, fluorescent imaging techniques are often adopted to investigate activities of cells. Previously, we have proposed the application of fluorescent imaging for the odor sensing system. The system relays a temporal change in odorant concentration via a change in fluorescent intensity by utilizing a cell with an olfactory receptor and a fluorescent protein. However, the system needs to be robust against ambient light as the fluorescent intensity is relatively weak. Additionally, the system should process the data in real time. In this study, many digital lock-in amplifiers were implemented into a field programmable gate array. An image taken from the image sensor was divided into 100 small areas where lock-in amplifiers parallelly worked in real time. The effect of the lock-in measurement for the image was demonstrated. Measurements of the cells under the different ambient light conditions confirmed that the system removed the influence of ambient light intensity. The developed system is capable of supporting the application of fluorescent imaging in real time sensing systems such as odor sensors.