Combining FEM and GA for Small PCR Temperature Unit Thermal Cladding Thickness Optimization

Accurate, fast and uniform of polymerase chain reaction (PCR) instrument control temperature are the key factors for high-efficiency DNA amplification. Although thermal cladding of a temperature unit can improve the stability of temperature control, the improper material thickness will also introduce negative influence, such as large dynamic error, slow respond. It is still a challenging of thermal coating thickness design in a miniaturized PCR instrument. Here, we propose a new coating thickness calculation method, which combines the finite-element method (FEM) and the genetic algorithm (GA) to pursuit the optimal coating thickness. Firstly, the temperature related units, which include a base, a heat dissipation, and a thermal cover, were modeled; Sequentially, to obtain the temperature field transient solution, the rules of heat transfer conditions were established; Furthermore, coating thickness, steady- and transient-state temperature fields are obtained through a GA optimization with temperature parameter constrained. In the numerical simulation experiments, the proposed method is verified by using a 16 holes, 40*40mm, aluminum PCR base. The results indicate that the optimal coating thickness is 19mm; the transient temperature control error is lower than ±0.15°C; and the uniformity of the base surface is lower than ±0.1 °C. The proposed method has significance for using in FEM-based manufacturing parameter or control parameter calculation.