Design and development of polymerase chain reaction thermal cycler using proportional-integral temperature controller

Abstract

A thermal cycler is used to amplify segments of DNA using the polymerase chain reaction (PCR). It is an instrument that requires precise temperature control and rapid temperature changes for certain experimental protocols. However, the commercial thermal cyclers are still bulky, expensive and limited for laboratory use only. As such it is difficult for on-site molecular screening and diagnostics. In this work, a portable and low cost thermal cycler was designed and developed. The thermal cycler block was designed to fit six microcentrifuge tubes. A Proportional-Integral temperature controller was used to control the thermal cycler block temperature. The results showed that the maximum temperature ramp rate of the developed thermal cycler was 5.5 °C/s. The proportional gain (Kp) and integral gain (Ki) of the PI controller were 15 A/V and 1.8 A/Vs respectively. Finally, the developed thermal cycler successfully amplified six DNA samples at the expected molecular weight of 150 base pair. It has been validated using the Eppendorf Mastercycler nexus gradient system and gel electrophoresis analysis

Long term temperature stability of thermal cycler developed using low profile microprocessor cooler

“…The mini thermal cycler, which is considered low cost, limits the cycling speed due to using hardware with a passive cooling mechanism for the cooling process. Although some work is reported on the development of the thermal cycler [7]- [10], the simplicity of the design using a limited budget may open a wider possibility for the development and usage of the thermal cycler.…”