A sensor designed to determine the amount and concentration of analyte in a sample having a volume of less than about 1 \u03bcL. The first electrode is a tube made of dielectric material, having at least one electron gun positioned proximate an end thereof for firing electrons. Each of the de-skinning devices can include a rotatable gripper roll which is circumferentially provided with longitudinally extending teeth having radial ends facing away from a rotational axis of the roll and providing a frictional outer surface to the roll for catching engagement with the skin. Then, fax control interrupt routine operation, fax panel display, and fax command reception are enabled.