Resistance thermometry-based picowatt-resolution heat-flow calorimeter

We demonstrate a microfabricated heat-flow calorimeter capable of measuring modulated heat currents with similar to 5 pW resolution. This is achieved by combining the excellent thermal isolation of a microdevice suspended by thin and long beams (conductance similar to 150 nW/K) with a high-resolution resistance thermometer that enables temperature measurements with 10-50 mu K resolution [Sadat et al., Rev. Sci. Instrum. 83(8), 084902 (2012)). The calorimeter described here has a resolution comparable to state-of-the-art bimaterial cantilever-based calorimeters but surpasses previous designs by dissipating an order of magnitude lower power in the measurement process. (C) 2013 AIP Publishing LLC [http://dx.doi.org/10.1063/1.4802239]