An Autonomic Function Testing (AFT) device is a medical tool used to assess the sympathetic and parasympathetic nervous systems, which control involuntary functions like heart rate, blood pressure, digestion, and sweating, with common examples being systems for Heart Rate Variability (HRV) analysis (like Intellewave), Sudomotor (sweat) testing (like Sudoscan, Q-Sweat), and comprehensive systems (like VitalScan, CANWin) that integrate multiple tests (e.g., deep breathing, Valsalva maneuver, head-up tilt) for diagnosing conditions like diabetes, orthostatic hypotension, and neuropathy. These automated devices provide objective data for diagnosing autonomic disorders.