Date of Graduation

12-2015

Document Type

Thesis

Degree Name

Master of Science in Mechanical Engineering (MSME)

Degree Level

Graduate

Department

Mechanical Engineering

Advisor

Steve Tung

Committee Member

Uchechukwu Wejinya

Second Committee Member

Po-Hao Huang

Keywords

3D Printing, Biosensors, Mechanical Engineering, MEMS, Microelectromechanical systems, Microfluidics

Abstract

A pneumatically actuated PDMS based microfluidic devices were designed and fabricated by soft-lithography. Two types of molds were fabricated out of different material for this experiment. The first mold, (device 1), was fabricated from a sheet of Polymethyl methacrylate (PMMA) material, similar to Plexiglas. The device features were micro-engraved onto the face of the material. The second mold, (device 2), was fabricated from the use of fused deposition modeling (FDM) 3D printing. The pumping efficiency of the PDMS devices was analyzed through the characterization of the micro-pumps flowrate with respect to the pumps driving pressure and the actuation frequency. Tested at a driving pressure of 10psi, the flowrate for device 1 peaked at 75µL/min with a 7Hz actuation frequency before failing, while device 2 peaked at 498µL/min with a 15Hz actuation frequency.

Using the techniques of rapid prototyping and fused deposition modelling a pneumatically actuated 3D printer based micro-pump and micro-mixer are fabricated. The devices were fabricated using a thermoplastic elastomer (TPE) material as an alternative material to the present polydimethylsiloxane (PDMS). The micro-pump’s fluid flow output was analyzed through the characterization of the micro-pumps flowrate with respect to the pumps driving pressure and the actuation frequency. Testing showed that a maximum flowrate of 1120µL/min was achieved at an actuation frequency of 10Hz with an applied driving pressure of 40psi. A qualitative mixing performance was conducted with the micro-mixer. The diffusion of two dyes was tested under an active mix and non-active mix condition. Testing showed that the active mixing condition resulted in a complete diffusion as opposed to the non-mixing condition which partially diffused. As a proof of concept for biological testing, E. coli and E.coli anti-bodies were mixes to measure the capturing efficiency. The results showed that the active mixing resulted in about 50% capturing efficiency as opposed to the non-mixing which resulted in 33% capturing efficiency.

Available for download on Thursday, November 16, 2017

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