The QTI Sensor is an infrared emitter/receiver that is able to differentiate between a dark surface) with low IR reflectivity) and a light surface (with high IR reflectivity). These little sensors can be very handy for line following, maze navigation, or sensing the outer rim of a SumoBot ring. Wiring options allow it to be used digitally for fast black/white line following, or as an analog sensor to detect different shades of gray. A daylight filter is built into the sensor.

What does QTI stand for?
  - Q = Charge
  - T = Transfer
  - I = Infrared

When your microcontroller measures the time it takes for the QTI's capacitor to decay, it's measuring a rate of charge transfer through an infrared phototransistor. This rate indicates how much infrared is reflecting off a nearby surface.

Features:
  - Capable of analog or digital outputs
  - No-contact surface sensing
  - Unfocused for sensing diffused surfaces
  - Daylight filter on sensor
  - Easy to interface with any Parallax microcontroller

Key Specifications:
  - Power requirements: 5 VDC
  - Communication: Analog output of capacitor decay time depending on level of infrared reflectivity
  - Dimensions: 1.25 x 0.37 in (31.7 x 9.4 mm)
  - Operating temp range: -40 to +185 °F (-40 to +85 °C)