Chip thermal cycler

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A chip thermal cycler is a thermal cycler with miniaturized reactors. Like other thermal cyclers, it is primarily needed for the polymerase chain reaction , with which DNA can be replicated outside of living cells.

principle

In contrast to conventional thermal cyclers, chip thermal cyclers work with very small sample volumes, typically in the lower microliter and nanoliter range. The small dimensions result in a low thermal inertia, so that fast temperature cycles can be achieved and the process times can be greatly reduced. The small sample volume also results in material and cost savings.

Stationary chip thermal cyclers

In the simplest case, a chip thermal cycler consists of one or more chambers into which the reaction liquid is introduced. During the temperature cycles, the entire component is periodically heated and cooled. The cycle time is determined, among other things, by the achievable cooling rates. An acceleration of the cooling can be achieved actively, e.g. B. with the help of Peltier elements . In addition, the cooling times can be optimized through the choice of the component geometry and the wall materials. The first chip thermal cyclers were produced on the basis of monocrystalline silicon . On the one hand, the well-developed technologies of microsystem technology , on the other hand, the good thermal properties of silicon could be used. Plastic-based chip elements that can hold minimal sample quantities for performing the PCR are cheaper to manufacture.

Chip thermal cycler for continuous operation

Instead of reaction chambers in which the liquid rests, flow reactors can also be implemented in chip format for thermocycling, so-called “ flow thermocyclers ”. For this it is necessary that the reactor channel is routed periodically through the different temperature zones. Because of the large surface-to-volume ratios, the choice of material and the passivation of the inner wall surfaces are particularly important in order to avoid disturbances of the reactions, for example through inactivation of the DNA polymerase , during the PCR.

Individual evidence

  1. ^ MA Northrup et al., Anal. Chem. 70 (1998), 918-922.
  2. ↑ S. Poser et al., Sensors and Actuators A 62 (1997), 672-675.
  3. ↑ V. Baier et al., DE4435107 C1 (September 30, 1994 / April 4, 1996).
  4. ↑ MU Kopp et al., Science 280 (1998), 1046-1048.