Interaction-Driven Transport of Molecules and Colloids in Microfluidic Devices
Open Access
- Author:
- Collins, Matthew D
- Graduate Program:
- Chemistry
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- January 21, 2020
- Committee Members:
- Ayusman Sen, Dissertation Advisor/Co-Advisor
Ayusman Sen, Committee Chair/Co-Chair
Thomas E Mallouk, Committee Member
Christine Dolan Keating, Committee Member
Darrell Velegol, Outside Member
Philip C Bevilacqua, Program Head/Chair - Keywords:
- Microfluidics
Transport
Nanomotors
Colloids
Macromolecules
Volume Exclusion
Acoustic - Abstract:
- Potential applications of smart materials at small scales such as diagnostic sensing, targeted drug delivery, nanomachines, robotics and self-assembly usually require transport other than Brownian diffusion. As a solution, systems need to be designed that use other mechanisms of non-reciprocal motion involving an asymmetry that usually involves some type of physical or chemical interaction with a gradient where a particle has to harvest energy from its surrounding environment and convert it to mechanical energy. Therefore, the main goal of this dissertation is to explore different mechanisms for the transport of molecules and colloids by chemical and physical interactions. Here, different transport mechanisms are explored in microfluidic devices driven by polymer gradients or acoustic power. In a polymer gradient, transport of dye molecules occurs by molecular chemotaxis because of the favorable thermodynamic binding in a non-reactive system. The molecular chemotaxis is shown to occur even in high viscosity environments that hinder transport. Additionally, larger colloids are shown to move away from similar polymer gradients by hard sphere repulsion. The transport of similar sized hard and soft colloids is compared in polymer gradients to see how the particle’s compressibility affects the observed movement. Furthermore, the effect of different microfluidic geometries such as a triangular nozzle and rectangular channel shapes are compared in the movement of acoustically responsive nanorods. The combination of nozzle geometry and acoustic power is shown to achieve unique focusing and perpendicular alignment of the nanorods even with a background flow. Overall, the different explored transport mechanisms show the usefulness of particle transport at the micro and nano scales.