FRET can be used to study biological events in molecular level, such as cancer development. Hence, the prototype design of a small, compact FRET image sensor is produced using CMOS technology. This sensor is capable of observing both cyan and yellow fluorescence light simultaneously in the same device. This is archived by placing an emission filter to eliminate excitation light over a CMOS image sensor with its pixel arrays coated with alternate lines of blue filter created through laser patterning process.