Rapid and Accurate Manufacture of 3D Vascular Replicas with Smooth Inner Surfaces Using Wax‐Coated Molds

Abstract

3D vascular replicas are an economical and ethical training platform that can simulate endovascular intervention. During the manufacture of elaborate 3D vascular replicas through sacrificial molding, the surface of the 3D‐printed pristine molds should be smoothed because the 3D‐printed layered filament is transferred to the inner surface of the replicas. However, conventional smoothing methods using organic solvents take >3 d, thereby limiting the emergency use of 3D vascular replicas. This study demonstrates the rapid and accurate manufacture of 3D vascular replicas with a smooth inner surface using wax‐coated molds. The wax coating can smooth the surface of the 3D‐printed pristine molds in ≈30 s, reducing processing time by >3 d. In addition, the thin and even wax coating, except for structures with a radius of curvature less than 2.5 mm or diameter less than 3 mm, facilitates the manufacture of elaborate 3D vascular replicas. The resulting replicas represent an internal vascular structure with high transmittance (≈90%) and mechanical properties similar to those of blood vessels, including Young's modulus and friction coefficient. Thus, the prepared 3D vascular replicas using wax‐coated molds can be applied as endovascular simulators in emergency situations.

Conformal Hydrogel-Skin Coating on a Microfluidic Channel through Microstamping Transfer of the Masking Layer

“…The hydrogel polymer covalently bonded to the exposed PDMS chains, that is, the microchannel, within and above the surface-bound diffusion layer during the UV irradiation because of benzophenone, thereby forming a hydrogel skin (Figure h). The reactions with the hydrogel polymer, such as polymerization, interpenetration, and grafting, were inhibited within the surface-bonded diffusion layer because the hydrophobic photoinitiator absorbed onto the PDMS surface did not diffuse into the hydrogel precursor solution, and the hydrophobic PDMS did not swell in water. − Finally, the un-cross-linked and unreacted hydrogel solution was completely removed via sonication in DI water for 30 min. This is ascribed to the un-cross-linking of the hydrogel precursor solution, which comprised only the monomer and photoinitiator without a cross-linking agent, under UV irradiation.…”

“…To create a hydrophilic PDMS surface, the pristine PDMS surface is oxidized by a plasma or ultraviolet (UV) irradiation to functionalize its silanol group. , Other surface-modification techniques involve grafting hydrophilic polymer chains, such as polyethylene oxide/polyethylene glycol, onto PDMS and incorporating amphiphilic surfactants into PDMS. − All resulting surfaces exhibit hydrophilicity and improved antifouling properties in relation to those of pristine PDMS; however, the oxidized surfaces have short-term stability, and the grafted polymer chains are susceptible to damage when subjected to external forces. , Recently, bulk-infiltrating cross-linked hydrophilic polymers, that is, hydrogel skin, have been integrated with PDMS surfaces . The hydrogel skin can offer long-term hydrophilicity, high mechanical robustness, and aerophobicity through a simple fabrication process, thereby drawing attention as an effective surface modification technique. − In addition, conformal coating is possible based on the shape of the target object. To date, the hydrogel skin has been coated in closed systems (bonded with a lid) to selectively modify microchannels only, thereby achieving simple physical masking (or blocking) of reagents .…”

Methods for Evaluating Friction between Intravascular Device and Vascular Biomodel

“…Samples with these shapes, rather than the tubular complex shape of medical devices, are adopted because they can be easily modified and characterized. For example, samples with simple shapes can be evaluated using standard tribological tests, allowing the use of commercial friction testers and rheometers [9,19,28,33]. Simple shapes are suitable for testing the material itself.…”

“…Experiments using more complex vascular models made of silicone rubber [29,[35][36][37][38][39], acrylic [40], poly(vinyl alcohol) hydrogel [25][26][27][30][31][32][33], and elastomer-hydrogel skin multilayers [9,28] that mimic living tissue have also been conducted. 3D printers are widely used to prepare biomodels and can easily fabricate mold copies of the vascular tree, which is subsequently embedded in a liquid resin that solidifies into a solid biomodel.…”

“…Biomodels that mimic various types of vasculature [9,[25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] can be used to test new endovascular medical devices and teach techniques to medical personnel; they also allow the practice and planning of procedures before treatment without exposing patients to X-rays. Moreover, biomodels are more economical and ethical compared to human cadavers and animals.…”