A nanocalorimeter device includes a substrate having test cells, each test cell comprising a sample location. Each sample location includes a reaction surface suitable for an enthalpic reaction of constituents of liquid droplets, droplet movement and configured to merge the droplets, and a layer of thermochromic material thermally coupled to the reaction surface. The thermochromic material is configured to exhibit a spectral shift in light emanating from the thermochromic material in response to a change in temperature of the merged droplets.