Abstract

Millions of people suffer from dentinal pain each year caused by a pressure change and fluid shear in the dentin tubule and nerve pulp system. Dentin is made up of mostly hydroxyapatite, a hard and opaque material. In-situ characterization is extremely challenging because of the tubules that run through are high-aspect ratio micropores with a feature size of 1-2 µm. Current studies have proven that various methods can be deployed to fabricate microscale geometry using PDMS. The most used methods are three-dimensional stereolithography, fused deposited material (FDM), 3D printed sacrificial mold, FDM 3D printed molds and soft lithography molding from the existing literature. This study simplifies dentin tubules by enlarging and creating a planar case for analysis. The chip geometry investigated consist of three 2 mm by 2 mm by 50 mm parallel channels separated by thin walls of 500 µm, 750 µm, and 1000 µm. The central channel is fitted with a glass capillary and holds liquid. The two outer channels are air pressure channels. The fabrication process is highlighted in this study and utilizes 3D FDM and 3D stereolithography (SLA) printing, negative molding of polydimethylsiloxane (PDMS), spin coating PDMS to create a 1 mm layer, and PDMS-PDMS bonding for chip completion. Pressure is applied to the completed chips in known increments and the dynamic response of the chip is recorded through image capture and processing. The experiments show a sequential, three process response. A strong linear correlation was found between steady state liquid surface height and applied pressure. The theoretical model can fit well the second and third processes of the response by ascertaining the initial height of the second process. The oversimplification and theoretical simulation results lay the groundwork for microfluidic devices that more closely model dentin tube structure, such as the polyvinyl alcohol (PVA) fibers positioned in an array to be tested in a similar fashion to the device in this study.

Publication Date

4-2022

Document Type

Thesis

Student Type

Graduate

Degree Name

Mechanical Engineering (MS)

Department, Program, or Center

Mechanical Engineering (KGCOE)

Advisor

Ke Du

Advisor/Committee Member

Kathleen Lamkin-Kennard

Advisor/Committee Member

Ruo-Qian (Roger) Wang

Campus

RIT – Main Campus

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