0
Research Papers

# Patient-Specific Compliant Vessel Manufacturing Using Dip-Spin Coating of Rapid Prototyped Molds

[+] Author and Article Information
Karina Arcaute, Ryan B. Wicker

W.M. Keck Center for 3D Innovation, College of Engineering, University of Texas at El Paso, El Paso, TX 79968

J. Manuf. Sci. Eng 130(5), 051008 (Aug 14, 2008) (13 pages) doi:10.1115/1.2898839 History: Received April 15, 2007; Revised November 06, 2007; Published August 14, 2008

## Abstract

A procedure for manufacturing cardiovascular system models using patient-specific data, rapid prototyping, and a multistep dip-spin coating process is presented here. Improvements to a previously developed process permitted the fabrication of flexible complex vascular replicas. The primary improvement included the development of a two-axis rotation mechanism that enabled a pseudorandom rotation of the coated mold in space, providing uniform coats. Other improvements included the use of a low viscosity $(1500–2000cP)$ silicone solution that allowed for complete coverage of the mold, and developing a procedure for fixing defects. The dip-spin coating procedure was shown to be effective for the manufacture of compliant cardiovascular membranes, such as an arterial bypass graft with an internal flow passage and an abdominal aorta with nonuniform radial geometry, tapered diameters, bifurcations, and small branches. Results from a design of experiments comparing two dipping setups demonstrated that horizontally dipping the model produced coatings with more uniform thicknesses along the length of the model when compared to vertical dipping. For a $250-mm$-long model, the difference in thickness between the top and bottom of the membrane was $0.42±0.069mm$ and $0.09±0.077mm$ for vertical and horizontal dippings, respectively. Mold diameter also affected the thickness of the membrane, with membrane thickness increasing as mold diameter decreased. Thickness data comparing locations at approximately the same height of the mold but with different diameters showed thicknesses of $2.54±0.198mm$ and $1.95±0.140mm$ for $7.85mm$ and $15.20mm$ diameters, respectively. Moreover, the differences in thickness between these locations were $0.60±0.128mm$ and $0.58±0.231mm$ for vertical and horizontal dippings, respectively; thus, membrane thickness variations occurred with mold diameter irrespective of the dipping setup. Depending on the prescribed tolerance for membrane thickness, the vertical dipping setup may be recommended for use because (1) it was easier to use since only the mold was immersed in the coating solution and no special protection of the dipping mechanism was required and (2) it produced fewer defects in the coatings since the solution always dripped from downfacing surfaces of the mold. Using this dip-spin coating procedure, patient-specific cardiovascular membranes can be manufactured and used in the development of medical devices, research requiring accurate anatomical models, and education and training.

<>

## Figures

Figure 13

Laboratory setup where the AAA model is used: (A) X-ray cabinet and bath setup (circled is the AAA model inside the bath); (B) AAA model in the bath; and (C) X-ray cabinet, working table, and monitor where the X-ray images are viewed

Figure 1

Process diagram for the manufacture of compliant silicone models

Figure 2

Effect of viscosity on the quality of the coating: (A) continuous coating obtained with a viscosity of 1500–2000cP and (B) defective coating obtained with a viscosity of 4500–5000cP

Figure 3

Dipping setups: (A) vertical and (B) horizontal

Figure 4

Biaxial rotation mechanism

Figure 5

Bypass graft models I, II, and III (from left to right): geometric computer model with dimensions (top) and silicone vessels (bottom)

Figure 6

(A) Buildup/void defect in a connecting section of a bypass graft model and (B) continuous membrane once the defect was repaired

Figure 7

Aortic arch model: geometric computer models (left) and silicone vessel (right)

Figure 8

Two different aortic arch silicone models manufactured by the following: vertical dipping rotated off center, side view (top left) and bottom view (bottom left); horizontal dipping rotated at the center of mass, side view (top right) and bottom view (bottom right)

Figure 9

Abdominal aortal model: geometric computer model (left) silicone vessel (right)

Figure 10

Features of the abdominal aorta silicone model. Bifurcations (top row) were repaired to obtain a water-tight vessel, and, as a result of the repair process, air (circled) was entrapped in the model. Differences in thickness can be seen along the model associated with the vertical dipping setup (pointing arrows in pictures in the center and bottom rows). Defects (air bubbles in small gaps between vessels) on the silicone model due to the mold geometry can also be seen (bottom row).

Figure 11

WaterWorks™ mold indicating the locations where thickness measurements were taken. The number below the location corresponds to the diameter of the mold (in millimeters) at each location.

Figure 12

AAA model: geometric computer model (left) and two views of the silicone vessel (right)

Figure 14

X-ray imaging of the AAA model being used to implant a medical device

## Discussions

Some tools below are only available to our subscribers or users with an online account.

### Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related Proceedings Articles
Related eBook Content
Topic Collections