A measuring device for detecting a metal object includes an emission coil configured to produce a magnetic field and a compensation network which is connected to the emission coil. Gas is conveyed from a cryostat to the insulated sleeve, where it is liquefied as it passes over the cold head. The use of PMD, in vitro, as an antiviral or virucidal agent. An identification of the patient is authenticated based on pre-defined uniquely identifying patient characteristics. An inner electrical insulator is disposed between the electrical conductors to electrically isolate the electrical conductors.