Deterministic Design of Thin-Film Heaters for Precise Spatial Temperature Control in Lab-on-Chip Systems

Spatial thermal control of localized fluid volumes is a major challenge in the lab-on-chip (LOC) field. Thin-film heaters are commonly used in LOC devices to carry out many key functions that require high temperature uniformity, including the polymerase chain reaction and melting curve analysis. However, the conventional heater design approach is to iterate from an initial best guess toward an optimal design, but without prior knowledge of the exact power distribution that is required to produce the desired temperature profile. Such an iterative process enormously increases the time and cost of the design process. We report on a novel methodology for rapid-turnaround design of thin-film heaters that generate a pre-determined high-resolution spatially controlled power density field that yields uniform temperature or any other desired temperature profile in a planar structure. High temperature uniformity in reaction chambers of arbitrary shape and size is achieved with a single metal layer heater, while maximizing energy efficiency and minimizing the footprint. We implement the method in a monolithic polymer chip architecture, and clearly demonstrate highly selective and uniform heating within 1°C in >94% of the chamber volume in four different designs at 95°C.