Closed chamber PCR-chips for DNA amplification

The polymerase chain reaction (PCR) is a well described method for the selective identical replication of DNA molecules. By an enzymatic in-vitro amplification process, the concentration of a DNA species is nearly doubled in a process, stepping through three different temperatures. In this way, the DNA concentration can be multiplied more than million-fold by 20 to 30 cycles of temperature. The advantages of miniaturized PCR chips are many such as rapid temperature cycling, smaller quantities of rather expensive reagents needed, low cost fabrication and the portability, which is of great use for environmental screening as well as in the medical sector. In this paper the fabrication and packaging of miniaturized reaction chambers etched into silicon are described. Advantages of the PCR chip are the small size of the chip (6 mm×4 mm×1.5 mm) and the sealing of the chamber with a Pyrex wafer using the anodic bonding method. The transparent surface of the Pyrex makes it possible to incorporate optical readout methods. The microchambers of 1 μl volume can be easily filled with the reagents using hypodermic needles and the fabrication process is simple. For fast thermocycling and control, platinum heaters and a temperature sensor have been integrated onto the chip. This ensures increased performance due to the closeness to the reagents and reduction of power and size. Only standard micromachining processes are used for the fabrication