A nanocalorimeter includes a merging layer having, a drop placement area for holding drops to be merged and a thermal equilibration area. A measurement layer includes a substrate, and a temperature probe on the substrate, wherein the temperature probe extends out of the surface of the substrate to come into operative contact with the thermal equilibration area when the measurement layer is placed in operative association with the merging layer. The nanocalorimeter is configured to have the merging layer and the measurement layer non-integrated, making the measurement layer reusable.