Miniaturized PCR chips for nucleic acid amplification and analysis: latest advances and future trends

Zhang, Chunsun; Xing, Da

In these techniques, temperature-sensitive materials such as thermochromic liquid crystals (TLCs) or fluorescence dye indicators are included in the PCR solution, variations in optical properties can be observed remotely. These techniques are categorized as semi-invasive since they involve a modification of the component in the solution and therefore could cause disturbances to the temperature field. (15) . Additionally, TLC solution has also been used to determine the rate of temperature change in the PCR microchannel (64) . Although this technique can directly obtain the spatial and temporal temperature distribution with a high precision of 0.18C, it usually has a small measurement range. The TLC's encapsulated spheres typically have a diameter of several ten micrometers and consequently it is hard to apply them in the PCR system with smaller characteristic dimensions. In addition, TLCs have to coexist with a PCR solution, which might affect the biological activity of the medium.