The use of ruthenium dioxide based thick-film resistors as secondary thermometers at temperature below 1 K is well known, but to-date their sensitivities have been less than those of comparable commercial germanium thermometers. Now researchers at the Institute of Experimental Physics and at the Technical University Košice, Slovakia, report the development of ruthenium dioxide thermometers suitable for temperatures in the millikelvin range (I. Bat’ko, M. Somora, D. Vanicky and K. Flachbart, Cryogenics, 1992, 32, (12), 1167–1168).

Films about 15μm thick were screen printed onto alumina substrates using commercially available ruthenium dioxide pastes. Provided they are designed for the purpose and a suitable paste is used, stable thermometers of high sensitivity and with a temperature reproducibility of within 1 per cent can be prepared from ruthenium dioxide films, for use at temperatures below 1 K.