A new micro-fluid chip calorimeter for biochemical applications

Based on a new thermopile heat power sensor, which was developed in MEMS technology, a miniaturized flow-through calorimeter was constructed. The heat power sensor consists of a silicon chip with a thin film BiSb/Sb thermopile and a PMMA reaction chamber. To ensure high signal resolution the heat power sensor is mounted inside a high-precision thermostat, which has a temperature stability of less than 100 μK. The heat power sensitivity of the calorimeter is 4–7 V W−1 depending on the thermal conductivity of the liquid, the height of the chosen reaction chamber and the volume flow rate. A limit of detection of less than 50 nW can be obtained for volume flows lower than 5 μl min−1. An important advantage is the low sample consumption of the calorimeter. For special applications the sample need for one measurement pulse does not exceed 20 μl.