The organic polymers of the invention have electrical semiconductor properties. Other embodiments are described and claimed. The photodetector includes a first photosensor exhibiting a first spectral responsivity and a second photosensor exhibiting a second spectral responsivity. A cap is provided that can cover food in the bowl or container preventing a pet from accessing the food. The present invention furthermore provides a method for manufacturing such a sensor device and a method for determining the presence andor amount of at least one component in a fluid using such a sensor device. The deciding, setting, enhancing, obtaining, and analyzing operations are repeated until a center of each searching ROI advances immediately before a given search limit.