Development of a Low-Cost and Portable Real-Time PCR Machine for Developing Countries

Real-time Polymerase Chain Reaction (realtime PCR) is an important medical diagnostic technique in which target DNA is amplified and the amplification process is monitored in realtime. However, most realtime PCR systems are expensive, especially for laboratories in developing countries. To increase accessibility to the realtime PCR technique, we developed a low-cost and portable real-time PCR system. The system was composed of two main parts: a thermocycler and an optical system. The thermocycler's core was a Peltier and a heatsink fan, in tandem with an electronic circuit to control the heating process’s temperature. A custom-made fluorescence optical setup was built using a blue LED chip (450 nm), an excitation filter, a dichroic mirror, an emission filter, and a CMOS camera. The results were displayed on a screen connected to a Raspberry Pi module. The thermocycler worked stably and accurately under the control of a PID controller. The system’s performance was tested using samples of rice phospholipase D (PLD) gene and maize Bt11 gene. The results showed that, at the end of the amplification process, fluorescence signals from positive samples were significantly higher than from negative samples. Nucleic acid amplification products were verified using gel electrophoresis. With the cost of ~$320 USD, the system could be a suitable candidate for realtime PCR tests in laboratories in rural and remote areas of developing countries.