Croquette is a co-inventor of magnetic-tweezer single-molecule biophysics, applying it to helicase/topoisomerase mechanochemistry, DNA replication, and nucleic-acid mechanics; his group also develops complementary single-molecule readouts (stereo darkfield interferometry, mass photometry-adjacent tracking) for sub-nanometer 3D localization. He continues active, well-cited methodological development (e.g., recent reviews of magnetic-tweezer principles) alongside Jean-Francois Allemand.