Disclosed herein are devices, systems, and methods for measuring an electropharyngeogram (EPG) in living organisms. In some embodiments, the devices and systems disclosed herein include an array for sorting and immobilizing an organism (such as a nematode) for measurement of an EPG and/or optical imaging. Also disclosed are methods for identifying therapeutic or toxic compounds utilizing the disclosed devices and systems. In some embodiments, the methods include screening for compounds with anthelmintic activity, toxicity (for example HERG channel blockers), or candidate drugs for treatment of a variety of human and/or animal diseases.