We describe a microfluidic platform for the automated culture, treatment and long-term highresolution imaging of Caenorhabditis elegans nematodes under normal physiological conditions. Our device features: (i) a microfluidic design tailored for the isolation of L4 larvae from a mixed larval population and for successive culture and treatment; (ii) a worm immobilization method, based on the thermo-reversible gelation of a biocompatible polymer inside the microfluidic chip, thereby enabling high-resolution imaging; (iii) an integrated temperature control system, both to ensure viable environmental conditions for C. elegans culture and to steer the worm immobilization/release process.