Götz Münchow and Klaus-Stefan Drese Fluidics and Simulation Department Carl-Zeiss-Straße 18-20, D-55129 Mainz Germany 1. General Elements of Amplification One of the most basic sources of information in biology is nucleic acid. While the nature of DNA (desoxyribonucleic acid) is comparable to a li- brary where all details are stored, RNA (ribonucleic acid) is more involved in information transfer. In the century of information technology, it is only natural to analyze both kinds of nucleic acids for identifying predisposi- tions (reading DNA) as well as the actual status of a biological system (reading RNA). However, the usually very low number of nucleic acid molecules, e.g., only two DNA strands of a single gene within a mammal- ian cell, lies beyond detection limits as long as detection techniques do not reach single molecule sensitivity. Moreover, the effort needed for electri- cal, optical, or chemical signal amplification is so high that such a tech- nique cannot be applied to numerous applications, especially in the field of point of care testing. Hence, the solution is not improving detection limits, but performing target amplification. For the nucleic acid amplification to occur, some type of copying ma- chine is required, because the sequence of a gene is a priori not known and currently there exists no sufficiently cheap method to read the information that would enable a subsequent synthesization in a more or less chemical approach. At this point, biology helps by providing different kinds of bio- logical copying mechanisms. As a consequence, most amplification strate- gies imitate microbiological processes, e.g., TMA (transcription mediated Institut für Mikrotechnik Mainz GmbH Chapter 13 Nucleic Acid Amplification in Microsystems