A device (10) includes a passive infrared sensor (20) for user interface. When a user places his finger over the infrared sensor (20), the sensor (20) generate a digital signal indicating the time, position, or movement of the user finger over the sensor (20). A digital signal processing unit (12) processes the digital signal through preinstalled algorithms and generates a command to execute the user instruction through infrared interface. In operation, the user finger does not need to touch or press the infrared sensor (20). In addition, the passive infrared sensor (20) may be packaged under a cover to protect the sensor (20) from hazardous elements in the environment.