Date of Graduation

5-2025

Document Type

Thesis

Degree Name

Bachelor of Science in Mechanical Engineering

Degree Level

Undergraduate

Department

Mechanical Engineering

Advisor/Mentor

Dr. Steve Tung

Committee Member

Dr. Steve Tung

Second Committee Member

Dr. Uche Wejinya

Abstract

Dielectrophoresis is a common method used to manipulate particles on the microscopic scale. Optically Induced Dielectrophoresis or ODEP is the specific method used in this research. All experiments were conducted in Dr. Tung’s Micro and Nano Systems lab at the University of Arkansas’ ENRC. An ODEP system was created in the lab for manipulating microbeads (6-10 micrometers (μm) in diameter) and E. coli cells (1-2 μm in diameter).

Experiments were performed on the microbeads to see how changing the parameters of the device affects the force caused by ODEP on the beads. The parameters that could be changed in the system were the color of projected light, the intensity of that light, the voltage applied by the function generator, and the frequency. Experiments were conducted by moving a microbead back and forth inside a ring of light at the greatest speed without losing the bead. The results showed an increase in voltage and light intensity both caused an increase in the force on the microbeads, and the color green had the greatest effect on the microbeads. The range of top speeds varied from 100-200 μm/s with the highest speed reached being 258 μm/s.

Experiments were performed on the E. Coli cells to see how long the cells would remain stationary without having to be moved with the ODEP force. Results showed that turning the voltage off while leaving the projector on allows the cells to stay stationary longer. Turning the voltage off meant the cells moved 4.5 times slower than when the projector was turned off.

The research being performed is focused on testing the limits of the system while also comparing how the microbeads are affected versus the E. coli cells. The testing done on the E. coli cells proved them to behave similar to the beads.

Keywords

optical dielectrophoresis; E. Coli cell; particle manipulation; microscopic

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