Method and device for liveness detection

A live subject tissue detection device includes a light source configured to emit light onto the tissue of a subject, a photodetector configured to receive light reflected from the tissue and light reflected from the blood flow, wherein the light reflected from the blood flow has a Doppler shift relative to the light reflected from the tissue, and generate a high frequency Doppler signal based on the Doppler shift, a detection circuitry configured to receive the high frequency Doppler signal from the photodetector and convert the high frequency Doppler signal into a low frequency signal, and at least one processor configured to compute parameters of the low frequency signal, compare the parameters of the low frequency signal to respective reference values, and determine a presence of live tissue based on the comparison.