Nanovoltmeter are sensitive voltmeters or voltmeter with a resolution of 1 nV (= 10E-9V) . The Model 2182A has a 7 1/2 Digit Display and has on the lowest 10mV full scale range a resolution of 1 nV. Low voltages are measured in biology (brain activity, cells stimulus potentials), for temperature measurements (thermocouple voltages, Seebeck effect) and of course in low temperature physics (superconductivity).