QTRX-MD-13A Reflectance Sensor Array: 13-Channel, 8mm Pitch, Analog Output, Low Current Shipping:1 day and there are driver chips

and there are driver chips like the MAX7219 that can control a matrix for you but there's a lot of wiring to set up and they take up a ton of space

see the MD series datasheet (1MB pdf)

modular boards and more accessible development boards like our very own SparkFun ESP8266 Thing

and also supports the latest v4

QTRX-MD-13A Reflectance Sensor Array: 13-Channel, 8mm Pitch, Analog Output, Low Current Shipping:1 day and there are driver chipspitch sensors size (mm) output max current optimal range LEDs board 8mm13 101. 0 16. 5 analogous 3. 5 mA 31 mA 10 mm This array of IR LED phototransistor pairs is great for precisely identifying changes in reflectance (like line detection). It operates from 2. 9 V to 5. 5 V and offers dimmable brightness control independent of the supply voltage and separate controls for the odd and even emitters. In general, the closer the object, the higher the