Fingerprint sensing system and method

A fingerprint sensing system, comprising:

• an array of capacitive sensors configured and arranged to measure capacitances caused by a portion of a finger located relative to the array of capacitive sensors, the capacitances comprising a first capacitance measured by at least one capacitive sensor in the array of capacitive sensors and a second capacitance measured by the at least one capacitive sensor, the first capacitance indicating a valley depth of a fingerprint of the finger at a first time and the second capacitance indicating the valley depth of the fingerprint at a second time;
• a detection unit configured and arranged to detect changes of said capacitances over time based, in part, on the first capacitance and the second capacitance, wherein said capacitances change over time in response to changes in the valley depth of the fingerprint due to pulsating blood in the finger;
• and
• a processing unit configured and arranged to determine if the changes of said capacitances substantially conform to a predefined liveness function, and to identify for each capacitance change, a relative position of a capacitive sensor in the array of capacitive sensors that is sensing the capacitance change.