Existing methods of human body temperature measurement are briefly analyzed. The opportunities of different type of medical thermometers are described. The advantages of the latest infrared skin thermometers and of new thermal imaging systems are evidenced. The thermoelectric power factor which determines the sensitivity of infrared detectors is modeled in highly conducting nanostructured organic crystals. The optimal parameters that ensure the highest value of the power factor at room temperature are evaluated. It is shown that in existing crystals of tetrathiotetracene-iodide after the optimization of carriers’ concentration it is possible to obtain higher values of power factor than in the best known inorganic materials. It is proposed to use these crystals as more efficient material for sensitive elements of thermoelectric sensors in infrared skin thermometry.