A fingerprint reader is an electronic device used to capture a digital image of the fingerprint pattern. The image captured with the fingerprint reader is called a live scan. This live scan is digitally processed to create a biometric template which is stored and used for matching.  It is important to remember that the fingerprint reader simply captures the biometric data.  The fingerprint reader itself does not perform any matching or comparisons.  There are three main types of fingerprint reader:

• Optical Fingerprint Reader:
  Optical fingerprint imaging involves capturing a digital image of the print using visible light. This type of fingerprint reader is essentially a specialized digital camera.  A light-emitting phosphor layer illuminates the surface of the finger. The light reflected from the finger passes through the phosphor layer to an array of solid state pixels which captures a visual image of the fingerprint.
  
  M2 Hamster Optical Fingerprint Reader
  M2-S Optical Fingerprint Reader
  
  
• Capacitance Fingerprint Reader:
  Capacitance fingerprint readers utilize the principles associated with capacitance in order to form fingerprint images.  In this method of imaging, the sensor array pixels each act as one plate of a parallel-plate capacitor, the dermal layer (which is electrically conductive) acts as the other plate, and the non-conductive epidermal layer acts as a dielectric.
  
  Upek TouchChip Capacitance Fingerprint Reader 
  
  
• Radio Frequency Fingerprint Reader:
  The fingerprint reader sends an RF signal into the finger. The signal is conducted across the area of the live sub-surface skin cells, while the dead outer skin layer conducts very little of the signal. Antennas in the sensor create an image of the fingerprint's valleys and ridges. The result is a protected sub-surface print.
  
  M2-S1 Radio Frequency Fingerprint Reader