the invention concerns methods and instruments for fast , selective replication of deoxyribonucleic acid from biomaterial through the known polymerase chain reaction , working in individual duplication thermocycles . the invention consists of extremely brief cycle times of only a few seconds for the pcr reactions , generated , on the one hand , by reaction chambers for the reception of the reaction solution constructed of a pattern of fine capillaries in close proximity to heating and cooling elements in order to optimally accelerate the temperature setting in the reaction solution for the three temperature phases of the pcr duplication cycles and , on the other hand , by keeping the flow rates in the capillaries to a minimum during the amplification phase so that the polymerase reaction is not disturbed . the capillary pattern can be simply produced by means of microsystern technology .