Do you know which exact type of sensor & led was used here, plus what components are needed to build the amplifying circuit?
It gives you the manufacturer and part numbers of the LED and Sensor in the article!
"The light-emitting diode (Siemens SFH487) and the phototransistor (Siemens SFH309FA)..."
And a circuit diagram of the amplifier!!!! With parts listed! What more could you want 
Or am I missing something in your question?