3D printed microfluidic device for combined thermal and fluorescence analysis

Abstract

Because temperature is one of the environmental factors that can influence chemical kinetics and fluid properties, there is a need for microfluidic devices that can control the temperature uniformity of the reaction zone to minimize errors in the analysis. A novel microfluidic device design leveraging the spatial freedom enabled through stereolithographic (SLA) 3D printing is presented. Building on advances in high resolution fabrication, a microfluidic device was created that can heat a sample volume of 5 \(\mu L\) between 30-90\(^\circ C\) with a spatial temperature variation of 0.3\(^\circ C\) or less. To achieve this level of spatial uniformity, the design incorporates removable support structures, channels for liquid metal loading to act as heating elements, and a central suspended hexagonal segment to provide thermal isolation from external connections and multi-axis heating. This device also features complete internal optical access for fluorescence-based measurements. Optimization of the temperatures within the device was performed using COMSOL multi-physics and validated against experimental measurements. The applicability and limitations of this device for DNA analysis are discussed, particularly the observed interactions between the PEGDA device and water or oil-based solutions at sustained higher temperatures.