Recent developments in integrated circuit calorimetry

In the present paper the properties of a new class of calorimeters, so called integrated circuit calorimeters (IC calorimeters) are discussed. IC calorimeters are constructed on the basis of micro-sized silicon chips with integrated thermopile and heater. The applicability of integrated circuits for calorimetric purposes strongly depends on their sensitivity and on an optimized area of the sensitive sphere. Thus the sensitivity has to be much higher than that of the heat power transducers of conventional calorimeters. The parameters of different integrated circuits are compared corresponding to their use in calorimeters. Different constructions of IC calorimeters are possible: batch and flow-through calorimeters operating at isoperibol or temperature scanning mode. As an example a batch type IC calorimeter for liquid samples with a resolution in heat measurement of <100 mu J is described in more detail. The applications of this calorimeter are represented in the paper with the investigation of enzyme catalysed reactions, i.e. the hydrolysis of urea and the oxidation of glucose catalysed by the enzymes glucose oxidase and catalase.