Assessment scales for Pressure ulcers are widely used, but these are not very precise since they rely on an assessment of the patient’s condition and are rather subjective. The PU sensor uses a proprietary method and instrument to assess blood flow in the superficial tissue. The technique is based on Photoplethysmography (PPG), which is a procedure where the skin is illuminated, and the reflected light is measured. The method and technique PU sensor use are based on an assessment of the individual’s physiological status, through an examination of the patient’s superficial blood flow when the skin is bearing the patient’s body weight. Early detection of patients having potential pressure ulcers is achieved.