Thermal modeling and design analysis of a continuous flow microfluidic chip

Abstract

Although microfluidics has demonstrated the ability to scale down and automate many laboratory protocols, a fundamental understanding of the underlying device physics is ultimately critical to design robust devices that can be transitioned from the benchtop to commercial products. For example, the miniaturization of many laboratory protocols such as cell culture and thermocycling requires precise thermal management. As device complexity scales up to include integrated electrical components, including heating elements, thermal chip modeling becomes an increasingly important part of the design process. In this paper, a computationally efficient, three-dimensional thermal fluidic modeling approach is presented to study the heat transport characteristics of a continuous flow microfluidic thermocycler for polymerase chain reaction (PCR). A two-step simulation model is developed, consisting of a solid domain modeling of the entire microfluidic chip that examines thermal crosstalk due to lateral diffusion across multiple thermal cycles, and a one pass simulation model to study the thermal profile in the fluidic domain as a function of critical parameters like flow rate and microchannel material. The results of the solid domain model are compared against experimental measurements of the thermal profile in a PDMS-glass microfluidic thermocycler device using a combination of thermocouples and an infrared (IR) camera. The suitability of the device in meeting the ideal thermocycling profile at low flow rates is established and it is further shown that higher flow rates lead to deterioration in thermocycling performance. Thermofluidic modeling tools have the potential to streamline the physical microfluidic device design process, reducing the time required to fabricate functional prototypes while maximizing reliability and robustness.