Acoustically Driven Micro Electro-Mechanical Mixers for Biomedical Applications

Open Access
- Author:
- Orbay, Sinem
- Graduate Program:
- Bioengineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- June 09, 2016
- Committee Members:
- Jun Huang, Thesis Advisor/Co-Advisor
Jian Yang, Committee Member
Siyang Zheng, Committee Member - Keywords:
- Micromixing
high-viscosity fluid
acoustofluidics
polyethylene glycol (PEG)
High viscosity fluids
Acoustofluidics
Artificial cilia - Abstract:
- Microelectromechanical systems (MEMS) have become enabling technologies on many research areas. In this dissertation, we present the use of acoustofluidic MEMS for bioengineering applications. Firstly, we demonstrate an acoustofluidic micromixer, which can perform rapid and homogeneous mixing of highly viscous fluids in the presence of an acoustic field. In this device, two high-viscosity polyethylene glycol (PEG) solutions were co-injected into a three-inlet PDMS microchannel with the center inlet containing a constant stream of nitrogen flow, which forms bubbles in the device. When these bubbles were excited by an acoustic field generated via a piezoelectric transducer, the two solutions mixed homogenously due to the combination of acoustic streaming, droplet ejection, and bubble eruption effects. The mixing efficiency of this acoustofluidic device was evaluated using PEG-700 solutions, which are ~106 times more viscous than deionized (DI) water. Our results indicate homogenous mixing of the PEG-700 solutions with a ~0.93 mixing index. The acoustofluidic micromixer is compact, inexpensive, easy to operate, and has the capacity to mix highly viscous fluids within 50 milliseconds. Secondly, we present acoustically actuated artificial cilia, which can also perform mixing into the PDMS microchannel as the natural cilia do. For the fabrication of artificial cilia structure into the channel, in situ fabrication method is used for the first time. In order to demonstrate the mixing performance of the artificial cilia device, we injected DI water and DI water + fluorescein powder solution via inlets and calculated the mixing index as ~0.9.