Simulation of Temperature Profiles due to Joule Heating in Microfluidic Systems

Abstract

Electrophoresis is a versatile method for the separation and analysis of proteins, DNA or RNA and other analytes. The applied electric field induces electric currents which generate Joule heating due to the buffer solution's resistance. The generated heat changes the mobility and diffusion coefficient of the analytes and therefore it degrades the system's performance. In order to investigate the spatial profile of temperature variations during electrophoresis, a comprehensive microfluidic system was modelled and validated. The physical characteristics such as electric field, current density, temperature generation, heat transfer and fluid flow were simulated in a vertical and horizontal two-dimensional working plane along the separation channel. An optimization study identified potential for improvement in order to reduce high temperature gradients and improve the heat transfer away from the separation channel. Due to the low thermal conductivity of air, a reduction in the chip thickness leads to an increase in temperature when not deploying sufficient cooling. Attaching a copper plate results in a maximal reduction of 49.1% due to its high thermal conductivity, while an active cooling 5°C below room temperature allows for an efficient heat dissipation resulting in 107% reduction in the highest temperature value.