Three-omega method to measure thermal properties of subnanoliter liquid samples

Abstract

There are growing needs to measure the thermal properties of small-volume liquid samples in various fields of bioengineering and microfluidics. Accordingly, there have been efforts toward miniaturization of the sensing device without substantially sacrificing the sensitivity. The minimum sample volume required for quantitative thermal analysis is currently in the 10 nl scale. In this work, we describe microfabricated sensors and a modified three-omega data-analysis scheme to determine the thermal conductivity k and volumetric heat capacity rho c(p) of samples of a few hundred picoliters. In experiments using several reference liquids, the technique measured k and rho c(p) of 750 and 375 pl samples. The measurement accuracies were similar to 10% for k and similar to 15% for rho c(p). (C) 2010 American Institute of Physics. [doi:10.1063/1.3441963]