A method to establish a linear temperature gradient in a microfluidic device based on a single multi-structure thermoelectric cooler

Linear cooling of continuous microfluidic is crucial to the microfluidic analysis of cell cryopreservation and homogenous ice nucleation. This study presents a method to establish a linear temperature gradient for linear cooling of continuous microfluidic based on a single thermoelectric cooler. A novel multi-structure thermoelectric cooler was proposed to generate a stable linear temperature gradient. Furthermore, a numerical model was established to explore the performance of linear cooling of continuous microfluidic. Meanwhile, experiments were carried out to validate the model. Based on the proposed multi-structure thermoelectric cooler, linear cooling of continuous microfluidic can be successfully achieved, even if the current of the thermoelectric cooler or microfluidic velocity changes. For the case of current equal to 3 A and microfluidic velocity equal to 50 mm/s, microfluidic can be linearly cooled from 297 K to 251 K with a cooling rate of 64.5 K/s and linearity of 0.9912. It was also found that the temperature gradient decreases slightly with increasing microfluidic velocity while the cooling rate increases and is approximately proportional to the microfluidic velocity. With the increase of microfluidic velocity, the linearity increases at first and then decreases. Maximum goodness of fit equal to 0.9942 appears at the microfluidic velocity of 20 mm/s.