Date of Graduation

5-2014

Document Type

Thesis

Degree Name

Bachelor of Science

Degree Level

Undergraduate

Department

Mechanical Engineering

Advisor/Mentor

Zou, Min

Committee Member

Couvillion, Rick J.

Abstract

Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene, commonly known by its brand name Teflon®, which has many desirable properties such as a low coefficient of friction, high temperature resistance, anti-microbial properties, hydrophobicity, biocompatibility, and chemical resistance. One of the major challenges caused by the non-stick property of PTFE is its poor adhesion to substrates: PTFE coatings can be easily detached from surfaces under frictional forces and shear. The molecule polydopamine (PDA) was discovered as the key protein for adhesion between polytetrafluoroethylene and substrates of many materials, including steel, and thus has been used as a unique approach for coatings. In this undergraduate thesis research, PDA will be examined as an adhesive layer to coat ultrathin PTFE coatings onto stainless-steel hypodermic needles that are subjected to friction during penetration tests to determine effectiveness of reducing forces experienced during needle insertion. The friction and adhesion properties of the coated surface was studied by creating a fixture to hold a thin polyethylene terephthalate (PET) film, and using a Bruker UMT Microtribometer (Bruker UMT) to force needle penetration while measuring the corresponding forces felt by the needle. It was found that the tip of the needle penetrated the PET film at a force on average 44.4% lower than the uncoated needles. During testing, the maximum force felt by coated needles was 125 mN compared to 225 mN for the uncoated needles.

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