Optimization of Thin Film Heaters for Spatial Polymerase Chain Reaction

Lab-on-Chip (LoC) technology has emerged as a powerful tool for biomedical diagnostics, chemical analysis, and environmental monitoring, offering compact and portable solutions. One key application is DNA amplification via Polymerase Chain Reaction (PCR), which replicates specific DNA sequences through thermal cycling. A challenge in conventional PCR is the time required for heating and cooling cycles. Spatial PCR addresses this limitation by allowing the sample to flow through a microfluidic network, where dedicated heaters maintain optimal thermal conditions across different regions of the chip. However, real-time detection of amplified products remains a challenge. Integrating photosensors in the annealing zone enables real-time monitoring of DNA amplification. This study focuses on the design, fabrication, and testing of thin-film heaters for spatial PCR. Using COMSOL Multiphysics, we simulated coupled thermal and electrical phenomena to optimize heater performance. The heaters, fabricated as a Cr/Al/Cr stack on a 5 × 5 cm2glass substrate, were designed to ensure uniform temperature distribution while minimizing thermal crosstalk. The configuration included a central heater for the denaturation phase (95 ℃) and two lateral heaters for the annealing phase (62 ℃). Thermal imaging confirmed uniform heating, assessing the integration of spatial PCR into LoC systems for efficient, real-time DNA amplification.