Seiichi Ikeda

Numerical evaluation method for catheter prototypes using photo-elastic stress analysis on patient-specific vascular model.

To date, no quantitative analysis has been developed to evaluate catheter performance inside the vascular lumen.

Photoelastic Stress Analysis on Patient-Specific Anatomical Model of Cerebral Artery

In this paper, we propose a novel method to develop biomimetic models using polyurethane elastomer, which has high photoelastic coefficient, and a method to analyze stress states on the model by photoelastic effect. By using this method, stress condition on vascular wall is clearly visualized on vascular fringe as rainbow-colored photoelastic pattern, and stress can be quantitatively measured from that pattern. Ideally, retardation and path length of transmitted light through the polyurethane model should be observed for photoelastic analysis. Our method has capability to observe these two parameters simultaneously. Retardation and path length were determined from RGB value of rainbow-colored photoelastic stress pattern and permeability of light, respectively. The accuracy of stress analysis was evaluated by tensile test using cylindrical polyurethane models. 5.73% error was found in the result of photoelastic stress analysis. Lastly using the model produced by new method, we could analyze stress states quantitatively on the model of cerebral artery. Consequently, our method should be valuable for not only surgical simulations but also hemodynamic studies and pathological studies.

Development of biodegradable scaffolds by leaching self-assembled magnetic sugar particles

Technologies to develop scaffolds with controlled diameter and high porosity have great significance in tissue engineering. We have fabricated biodegradable 2D and 3D scaffolds with ordered array of pores by casting polymer on self-assembled d-fructose (sugar) microspheres. First, ferrite microparticles were encapsulated in sugar spheres to make them become magnetized. After sieving magnetic sugar particles, those diameter-controlled particles were attracted by a magnet to form a self-assembled template for polymer casting. Interspaces of self-assembled template were successfully infiltrated with polymer. After removal of sugar particles, ordered array of pores were generated on the surface of scaffolds. Elastic modulus of a sheet-like scaffold was measured to be 2.0 MPa and was reasonably lower than that of a nonporous sheet. The biocompatibility of the developed scaffold was confirmed by the viability of human umbilical vein endothelial cells.

Fabrication of Transparent Arteriole Membrane Models

We made transparent arteriole membranous models by using grayscale lithography. We employed a sacrificial model made of WAX and PVA mixture as a novel molding material. Our goal is to complement previous surgical simulators for practice and rehearsal of medical treatments. Since block vessel models cannot recreate moderate compliance which is similar to that of the real blood vessel, here we propose fabrication method for transparent arteriole membranous model which has circular cross section smaller than 500 mum in diameter. Fabrication method of the model as well as evaluation result of the molding material is reported.

PHOTOELASTIC Stress Analysis on Patient-Specific Anatomical Model of Cerebral Artery by Reflection Method

Artery models and surgical simulators are required for safety surgery. We have proposed a novel method to produce biological models using polyurethane elastomer, which has high photoelastic coefficient. And a method is to analyze stress on the model by circular polarized light method. the quantitative stress is analyzed from rainbow-colored photoelastic pattern. But the measurement area is restricted for the fringe area of the artery model. In this paper, we propose stress measurement on biological model by reflection method, which is a stress measurement method using photoelastic effect. With this method, stress is measured in area wider than that of circular polarized light method. For the reflection method, the Reflection layer was coated between first layer of polyurethane elastomer and second layer of it. From SEM image of cross section of this artery model image, we confirmed uniform thickness of acrylic resin and adhesion between polyurethane layer and acrylic layer. To use this reflection model, We could quantify the error of photo elastic stress analysis. the measurement accuracy of stress state of model reflection area was found to be 9.1% about stress magnitude and plusmn 7[deg] about stress directions. And an application on artery model is verified experimentally. Finally, Stress on the vascular wall caused by the contact with a catheter was successfully measured. Consequently, it should be valuable for various applications not only surgical simulations but also hemodynamic studies and pathological studies.

Patient-Specific Blood Vessel Scaffold for Regenerative Medicine

In this research, we propose a method to construct an artificial blood vessel scaffold with patient-specific complex 3-dimensional shape and biocompatible porous polymer membrane adapted for cell cultivation, by introducing salt leaching technique into a fabrication technique for patient-specific 3D blood vessel model proposed by authors. In this method, a membranous PVA (polyvinyl alcohol) structure of desired 3-dimensional blood vessel shape was fabricated based on CT data. And the PVA structure was dip coated with polymer solution made by dissolving the Caprolactone (3wt%) and NaCl particle (27wt%) into chloroform (organic solvent), Finally, the NaCl particle and the membranous PVA structure were both eluted from the structure by dissolving these materials under water, and finally a patient-specific blood vessel scaffold with desired 3D vascular shape was constructed. Presented scaffold has the mechanical compliance similar to human blood vessel and provides porous polymer structure appropriate for cell cultivation.