Construction of low-cost PCR system with PID temperature control and digital filters for amplifying multiclass biological samples

This article presents the development and construction of a low-cost polymerase chain reaction (PCR) system designed to amplify DNA from different samples using accessible materials. Temperature measurement was performed with an NTC thermistor integrated into a circuit that incorporated a digital filter and was housed inside the sample holder. The heating mechanism operated with stage-specific configurations and used a full-bridge driver to supply a Peltier cell. During the initial denaturation stage, PID control was activated immediately to improve thermal stability, and the PWM output range was fixed to ensure a consistent response. In the subsequent stages, full power was applied to the Peltier cell during temperature transitions until the system approached the setpoint, after which PID control began regulating the temperature. The performance was evaluated against 2 commercial units. In the first test, the device required 3 hours and 16 minutes, which was 31 minutes longer than the commercial unit; regarding the second test, it required 1 hour and 50 minutes, completing the process 10 minutes faster than the commercial unit, amplification was successful for all samples. Overall, this low-cost PCR system demonstrated potential to function as an accessible alternative for laboratories with limited resources.