Thermopile chip based calorimeter for the study of aggregated biological samples in segmented flow

We present the first silicon chip-based calorimeter with segmented-flow technology (SFT) for the study of solid and aggregated samples. Solid particles or biological aggregates up to 1.5 mm are immersed in segments of aqueous solutions. The segments are transported to the heat flow detector of the calorimeter by a carrier liquid. The interfacial tension between the aqueous segments and the water immiscible carrier liquid ensures plug flow and prevents sample dispersion. At a typical segment volume of 11 μL, a volume specific calorimetric resolution of 2 mW L^-1 is achieved. The proper functioning of the new calorimeter is proved by measuring the metabolic heat production of biofilms cultivated on glass beads and by measurement of the basal microbial activity of soils. Results demonstrated the capability of the device to measure solid samples with coarse texture. With the implementation of the segmented-flow technology, the application range of chip calorimetry is substantially extended.