Recent developments in integrated circuit calorimetry

In the present paper the properties of a new class of calorimeters, so call ed integrated circuit calorimeters (IC calorimeters) are discussed. IC calo rimeters are constructed on the basis of micro-sized silicon chips with int egrated thermopile and heater. The applicability of integrated circuits for calorimetric purposes strongly depends on their sensitivity and on an opti mized area of the sensitive sphere. Thus the sensitivity has to be much hig her than that of the heat power transducers of conventional calorimeters. T he parameters of different integrated circuits are compared corresponding t o their use in calorimeters. Different constructions of IC calorimeters are possible: batch and flow-through calorimeters operating at isoperibol or t emperature scanning mode. As an example a batch type IC calorimeter for liq uid samples with a resolution in heat measurement of <100 mu J is described in more detail. The applications of this calorimeter are represented in th e paper with the investigation of enzyme catalysed reactions, i.e. the hydr olysis of urea and the oxidation of glucose catalysed by the enzymes glucos e oxidase and catalase.