Shayan Davani

Date of Award

Winter 2-23-2019

Document Type


Degree Name

Doctor of Philosophy (PhD)


Micro and Nanoscale Systems

First Advisor

Niel Crews


This work presents a novel counter-flow design for thermal stabilization of microfluidic thermal reactors. In these reactors, precise control of temperature of the liquid sample is achieved by moving the liquid sample through the thermal zones established ideally through the conduction in the solid material of the device. The goal here is to establish a linear thermal distribution when there is no flow and to minimize the temperature change at flow condition. External convection as well as internal flowinduced effects influence the prescribed thermal distribution. The counter-flow thermal gradient device developed in this study is capable of both stabilizing the thermal disturbance caused by the flow as well as establishing a significantly linear distribution. A temperature ramp rate of up to 102 ºC/sec was achieved for a 30 ml/hr flow rate. This configuration removes the obstacles in the way of performing temperature sensitive biological processes such as PCR and DNA melt analysis at remarkably shorter time.

Mathematical modeling including the analytical models as well as simulations was performed for a better understanding of the transport phenomena occurring in the designed microfluidic devices. External convection impact on the uniformity and linearity of the thermal distribution and the ways for minimizing it were investigated experimentally, analytically, and numerically. Also, the dissipation of a small thermal event generated from an exothermic mixing in a continuous flow thermal sensing system was investigated, and a novel numerical model was developed for suggesting the optimum location for sensing the heat using a thermoelectric sensor.