Comment Re:Hemoglobin? Uh. Not quite. (Score 3, Insightful) 107
Cut off the hand in such a way as to keep the appendage from bleeding out (think fire-heated axe), and there's still going to be blood (and hemoglobin) in there.
Pretty sure it uses the RF properties of iron when in motion. If it does use IR, then the blood needs to be a different temperature than the skin. Cutting off the hand would cause the blood to cool too much.