Microfluidic in-chip temperature control via the heat of mixing release

摘要: This paper presents a novel method to control the Temperature of liquid mixtures flowing through a microfluidic device. The theoretical background is explained, the design discussed, and the test results reported. The control is performed directly within the channels, exploiting the enthalpy of mixing: two chemicals are mixed via an ad-hoc designed device, and their mixing ratio is the controlling input that sets the temperature of the fluid at any level in [T0; T0+ ΔTmax]. This technique allows for a stable fluid Temperature, it is easy to implement and does not require any auxiliary device. Several chemicals have been investigated, and the most promising was the pair Water-Dimethyl Sulfoxide (DMSO), which provides a ΔTmax of 32 K. DMSO is often used in microfluidics, being cheap, safe and available. The dilution with water is optimal for any biology-related process and for those that involve heat harvesting. This mixture is fully compatible with PDMS, the most widely used polymer in microfluidics. Results are compared to CFD simulations, also used as improvement tool for the selected mixer geometry, to reduce Pressure drop and Entropy generation. Some applications of this device are discussed in the article.