Researchers are developing AI-driven smartphone applications to detect signs of depression non-invasively. One system, PupilSense, monitors pupillary reflexes to identify potential depressive episodes with 76% accuracy. Another tool, FacePsy, analyzes facial expressions and head movements to detect subtle mood shifts, with unexpected findings like increased smiling potentially linked to depression. These tools offer a privacy-protective, accessible way to identify depression early, leveraging everyday smartphone use.