The nucleic acid amplification reaction has extremely high requirements for the precision of temperature control. The conventional PID control algorithms exhibit limitations in nonlinear and time-varying PCR temperature control systems, including poor adaptive parameter adjustment, excessive overshoot, and insufficient steady-state precision, which directly restricts the efficiency and specificity of nucleic acid amplification. This paper focuses on the design and optimization of the fuzzy PID temperature control algorithm. By combining the nonlinear adaptive advantages of fuzzy control and the steady-state precision of PID control, a temperature control algorithm model suitable for the thermal convection nucleic acid amplification instrument was constructed. This device can adapt to the thermal convection temperature control mode, providing a stable reaction platform for the subsequent algorithm performance testing and nucleic acid amplification experiments. For this fuzzy PID temperature control algorithm, this study established a simulation model using MATLAB/Simulink R2020a by defining the fuzzy input and output variables and designing the membership functions and fuzzy rule base. A performance comparison of temperature control was then conducted between this algorithm and the conventional PID algorithm. The nucleic acid amplification experiment verified the effectiveness of this algorithm in practical applications. The simulation results demonstrate that the fuzzy PID algorithm significantly suppresses the system overshoot, effectively shortens the adjustment time, and achieves a steady-state control precision of ±0.05 °C. The temperature control system equipped with this algorithm achieves a heating rate of 7.5 ± 0.1 °C/s, a cooling rate of 13.5 ± 0.1 °C/s, a steady-state temperature deviation of only ±0.1 °C, and an amplification efficiency of 98.7%. All performance indicators are superior to those of the conventional PID temperature control system and existing commercial instruments. This fuzzy PID temperature control algorithm provides crucial technical support for enhancing the efficiency, specificity, and repeatability of nucleic acid amplification, and holds broad application value in the biotechnology field with high requirement on precision temperature control.
Wang et al. (Wed,) studied this question.