NUMERICAL ANALYSIS OF ANNEALING IN AN ANNULAR TUBE USING NANOPARTICLE-ENHANCED PHASE CHANGE MATERIAL

The recent outbreak of a pandemic has driven microfluidics research toward reducing pathogen identification delays. Microfluidic polymerase chain reaction (PCR) modules enable efficient heat transfer and compact point-of-care applications but struggle with rapid temperature shifts. Nanoparticle-enhanced phase change materials (NePCMs) offer promising passive thermal management for improved DNA amplification efficiency. This study explores combining minichannels with NePCMs containing Al<sub>2</sub>O<sub>3</sub> and CuO nanoparticles for stable annealing temperatures. Computational analysis of a continuous flow PCR pathway shows NePCM-bounded channels rapidly achieve and sustain optimal annealing conditions. A parametric study found that a 4 mm wide NePCM capsule for a 30 mm long channel achieves a stable isothermal region rapidly, and further experimentation showed that increasing concentrations of Al<sub>2</sub>O<sub>3</sub> and CuO nanoparticles significantly reduce the annealing temperature. A NePCM with both types of nanoparticles (at volume fraction, Φ = 10%) outperforms the base PCM by increasing the isothermal region length by 30% to 50%. Among the nanoparticles, CuO extends the isothermal length by 10% to 12% more than Al<sub>2</sub>O<sub>3</sub>. Moreover, CuO achieves isothermal equilibrium faster than Al<sub>2</sub>O<sub>3</sub>, demonstrating superior performance compared to its counterpart. This study on thermal management using nanoparticles in thermocycler development shows potential for creating portable PCR devices for pathogen detection.