Capillary thermocycler

Fig. 1. Prototype thin-film resistive heating PCR thermocycler (TFRT). (I) Overall TFRT design schematic. (II) Schematic and views of the TFRT capillary cartridge assembly. The device components are 4 Thin-film resistive heater B1 and B2fans Cthermocou-ple D PCR capillaries E1 and E2 relays F computer interface 6 control software H power source (batteries or power supply).

Figure 1A is a schematic of the temperature measurement and control circuit. A type T thermocouple (see Note 2), inserted in a glass capillary, measures the temperature of a capillary with similar characteristics to capillaries holding the reaction mixture. The thermocouple is connected to an A/D channel of the data acquisition system (DAS) in a differential configuration (rrrNote 3). The DAS system is also used to communicate output commands (D/A channels) from the computer to the thermocycler. The DAS system employed in this study has eight channels available that can be used as either inputs or outputs. The fans and the heater are connected to the output channels of the board via solid state relays. 

A big additional advantage of flow-through processes in comparison with stationary processes consists in the possibility of implementation of process chains (Fig. 7). In this way, complete microanalytical systems can be designed [13]. They can include sample pretreatment like cell separation, cell lysis, or chemical separation. Reverse transcription processes can be directly ctamected on-chip with the DNA amplification by thermocycling (RT-PCR). The analytical chain can also include post-amplification steps like fluorescence labeling, separation by capillary electrophoresis, or hybridization on DNA chips. 

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