Toward high-throughput chip calorimetry by use of segmented-flow technology

• Chip calorimeters with sample transport in segmented flow.
• Analysis of the signal dynamics under segmented-flow conditions.
• Suppression of biofouling in the flow channel.
• Heat production of spheroids.
• Heat production of human hair follicles.

The adaptation of segmented-flow technology to flow-through calorimetry was demonstrated by different kinds of newly designed chip calorimeters useful for liquids and suspensions as well as for solid samples. In segmented-flow technology, sample material is suspended in aqueous segments of nano- or microliter volume and transported by a water-immiscible carrier liquid. The analysis of the signal dynamics given by segmented samples in flow led to optimal settings of flow rate and sample volume for maximal throughput. For 12 μL sample segments, a cycle time of 4 min could be achieved. The protection of the measuring chamber of the calorimeters against biofouling caused by the water-immiscible carrier liquid was verified for segmented bacterial samples. The unique possibility to measure solid and aggregated samples in flow-through was demonstrated by the investigation of human hair follicles and fibroblast spheroids.