The Eyeblink 2 Switch uses an invisible infrared beam to detect eyeblinks, and discriminates between voluntary and involuntary blinks and only responds to voluntary blinks. It can be set up very quickly, and requires minimal calibration. It calibrates automatically and has Sensitivity and Duration Controls for additional fine tuning. It continuously re-calibrates to accommodate changes in background infrared levels (e.g. from changes in sunlight, and fluorescent lights being turned on and off), reducing the need for adjustment after it has initially been set up.
