A silicon planar microcalorimeter as biosensor for the monitoring of substances of biotechnological and clinical interest

A new kind of biosensor allowing the measurement of the heats of biochemical reactions is presented. It is based on the principle of the thermocouple, but is integrated onto a silicon chip. Its high sensitivity together with its ability to reject common-mode thermal signals enables measurement of temperature changes in the order of 0.1 mK in a flowing stream without controlling the external temperature. The universal technique of calorimetry combined with the specificity of enzymatic and immunoassays makes this biosensor very versatile, with a broad range of applications. Examples of the determination of glucose, urea and other substances of clinical or biotechnological interest using calorimetric sensors in conjunction with flow injection analysis are described.