Research on optimization strategies for thermal management system of digital microfluidic chips based on thermoelectric cyclic-thermal regulators

To meet the stringent requirements of rapid temperature changes in the polymerase chain reaction (PCR) process for digital microfluidic chips, this study investigates the transient heat transfer characteristics and optimization strategies of the PCR process based on thermoelectric cyclic-thermal regulation. Research has shown that transient cooling is more efficient than steady-state cooling, and the dimensionless optimal values Z_HT and Z_CT for thermoelectric materials under transient conditions have been derived. It was determined that the thermoelectric leg height providing high heating and cooling heat flux should be between 0.5∼ 0.7 mm, and it was also found that smaller H values lead to higher temperature control stability. When the equivalent heat capacity exceeds 8.5 J/K, it is capable of achieving at least 4.02 W/cm² of cooling heat flux and 13.02 W/cm² of heating heat flux, providing a basis for the miniaturization design of the heat sink. Through optimization of the heat dissipation structure, a thermal management system using PID control was implemented, achieving a heating rate of 8.78 °C/s and a cooling rate of 5.33 °C/s. Furthermore, the system supports an array of multiple temperature control units. This study offers design and optimization strategies for the thermal management system in microfluidic systems and provides theoretical support and experimental data for thermal cycling scenarios.