Design and fabrication of portable continuous flow PCR microfluidic chip for DNA replication

The reasons for restricting continuous flow polymerase chain reaction (CF-PCR) microfluidic chip from lab to application are that it is not portable and requires costly external precision pumps for sample injection. Herein, we employed water as the substitute for PCR solution, and investigated the effect of the cross-section, width-to-depth ratio, and the length ratio for three temperature zones of the micro channel on the thermal and flow distribution of fluid in micro tube by finite element analysis. Results show that the central velocity is uniform and stable velocity occupies the most if the cross-section is rectangular. The deviation between predefined temperature and theoretical temperature is slight and the fluid flux is the most if width-to-depth ratio is 1:1. It is suitable for the short DNA replication if the high temperature zone W_h is larger than the low temperature zone W_l, and vice versa. Then a portable CF-PCR microfluidic chip was fabricated and an automatic sample injection system was developed. As an application, we have successfully amplified the DNA of Treponema denticola in the chip within 8 min. Such a study may offer new insight into the design of CF-PCR microfluidic chip and promote it from lab-scale research to full-scale application.