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Dynamic nuclear polarization with photo-excited triplet electrons (Triplet-DNP) is demonstrated using 6,13-diphenylpentacene (DPPentacene). DPPentacene is soluble in various organic solvents, while pentacene, which is used in most of the triplet-DNP experiments, has limited solubility. An enhancement factor of 81 is obtained for 1H spins in the glass of ethanol-d6 : water = 80 : 20 (w/w) doped with 0.1 mM DPPentacene at 90 K in 0.67 T.

Dissolution dynamic nuclear polarization (DNP) has wide variety of important applications such as real-time monitoring of chemical reactions and metabolic imaging. We construct DNP using photoexcited triplet electron spins (Triplet-DNP) apparatus combined with dissolution apparatus for solution NMR in a high magnetic field. Triplet-DNP enables us to obtain high nuclear polarization at room temperature. Solid-state samples polarized by Triplet-DNP are transferred to a superconducting magnet and dissolved by injecting aqueous solvents. The 13C polarization of 0.22% has been obtained for [caryboxy-13C]benzoic acid-d in the liquid state. Our results show that Triplet-DNP can be applied to real-time monitoring with solution NMR.

Background The photoelastic effect is used for stress measurement during endovascular surgery simulation for quantitative evaluation of catheter trajectory in in vitro environments. By extending the capabilities of this sensing technology, its potential for intravascular tools evaluation will increase. Methods In this research the error introduced by stress direction on magnitude measurements was studied, then stress measurements were made in the phantom modelling of a saccular aneurysm with bleb. To visualize three-dimensionally the stress field changes produced by a guide wire in a phantom wall, a scanner and an algorithm relying on maximum likelihood-expectation maximization are proposed. Three-dimensional fields at different pressure level were compared with the stress field surrounding the guide wire. Results The maximum error in stress magnitude measurements due to stress direction was 2.52%. Stress local maximum was detected in the bleb phantom before rupture. Three-dimensional visualization was obtained in vasculature phantom with average errors of 10.73%, 4.55%, 3.18% for inner pressures of 80, 120, 160 mmHg, respectively. Stress measurement in the neighbourhood of the guide wire is equivalent to applying an inner pressure of 120 mmHg. Conclusions For the presented polariscope, the weak influence of stress direction in magnitude measurements was confirmed. In vasculature phantoms, the three-dimensional visualization of stress eliminated birefringence visualization distortion and enabled more comprehensive comparison of stress produced by intravascular tools with stress produced by normal blood pressure. Copyright © 2010 John Wiley & Sons, Ltd.

Real-time and accurate stress calculation in walls of vasculature is a desired goal in order to provide feedback control for catheter insertion robots without changing catheter stiffness and lumen. This feedback source also has applications in endovascular surgery simulation. In order to address this need, we consider photoelastic effect, as birefringence produced by light retardation relates to the stress inside photoelastic materials. In this research, a polariscope was designed for urethane elastomer vasculature models, the photoelastic coefficient of urethane elastomer was measured, and a camera system was calibrated to quantify and reduce error in the measurement system. An average error of 3.9% was found in stress measurements for the pressure range of 60-189 mmHg inside the urethane elastomer model. This result was applied to correct stress distribution images, using the average stress value as a reference and preserving local maxima and minima of stress. This enabled us to accurately calculate stress in vasculature models during human blood pressure simulation (HBPS), and enables the comparison, in a closed loop, of stress produced by HBPS and by catheter motion when driven by a robot, as well as to measure the stress produced by medical tools on the vascular model wall.

Numerical criteria for evaluating stress on vasculature models have applications in evaluating medical tools and surgical skills enabling better endovascular surgery training and the development of better medical techniques and tools. We propose using the stress produced by blood pressure simulation in the vasculature model wall for this criterion and use photoelastic effect for measuring the principal stress magnitude component. We simulated human blood pressure with 5.6% average error and developed shielded urethane model of vasculature enabling water circulation and avoiding plastic deformation at pressures below 182 mmHg. We developed software to calculate model wall stress. We quantitatively compared in four ranges stress produced on the model wall by blood pressure simulation and a guide wire.

Biodegradable scaffolds are of great value in tissue engineering. We have developed a method for fabricating patient-specific vascular scaffolds from a biocompatible and biodegradable polymer, poly( l -lactide-co-ɛ-caprolactone). This method's usefulness is due to flexibility in the choice of materials and vascular configurations. Here, we present a way to fabricate scaffolds of human carotid artery by combining processes of rapid prototyping, lost wax, dip coating, selective dissolution, and salt leaching. The result was the successful development of porous biodegradable scaffolds, with mechanical strength covering the range of human blood vessels (1–3 MPa). Human umbilical vein endothelial cells were also cultured on the scaffolds and their biocompatibility was confirmed by cell growth. The Young's modulus of scaffolds could be controlled by changing polymer concentration and porosity. The wall thickness of the tubular scaffold was also controllable by adjusting polymer concentration and pull-up velocity during dip coating. We believe that this fabrication technique can be applied to patient-specific regeneration of blood vessels.

In this paper, we propose a novel method to product biological models using polyurethane elastomer, which has high photoelastic coefficient and a method to analyze stress states on the model by photoelastic method. With this method, stress condition on vascular wall represented by two principal stresses is clearly visualized on vascular fringe as rainbow-colored photoelastic stress pattern, and the quantitative stress is analyzed from that pattern. For analysis of stress states by photoelastic method, retardation and path length of penetration light through the model must be observed. Proposed method is possible to observe these two parameters simultaneously. Retardation is decided from RGB value of rainbow-colored photoelastic stress pattern and path length is decided from permeability of light. The accuracy of stress analysis is evaluated by tensile test using artery-like cylindrical model. Lastly using the model produced by new method, we analyze stress states quantitatively on the model of cerebral artery. Consequently, it should be valuable for various applications not only surgical simulations but also hemodynamic studies and pathological studies.

Technologies to develop scaffolds with controlled pore layout and porosity have great significance in tissue engineering. As one method of scaffold fabrication, porogen leaching has been commonly used to control pore size, pore structure and porosity in the scaffold. In this paper, we describe a novel approach to fabricate 2D and 3D porous biodegradable scaffolds made of poly(L-lactide-co-epsiv-caprolactone) by using magnetic sugar particles as porogens. First, ferrite micro/nano particles were encapsulated in sugar microspheres to make them magnetized. After sieving magnetic sugar particles, those diameter-controlled particles were attracted by a magnetic force to form an assembled template for polymer casting. A magnetic field with polka-dot pattern was also utilized to align particles on desired positions. After polymer casting and removal of the sugar template, spherical pores were generated inside scaffold. For future application in vascular tissue engineering, we extended the scaffold fabrication to straight tubular scaffolds by winding 2D porous sheets on sacrificial molds. The biocompatibility of the developed scaffold was confirmed by viable cells after 4-day culture.

This paper presents a novel hybrid medical stent device. This hybrid stent device formed by fractal mesh structures provides a flow-diverting effect and stent-assisted coil embolization. Flow-diverter stents decrease blood flow into an aneurysm to prevent its rupture. In general, the mesh size of a flow-diverter stent needs to be small enough to prevent blood flow into the aneurysm. Conventional flow-diverter stents are not available for stent-assisted coil embolization, which is an effective method for aneurysm occlusion, because the mesh size is too small to insert a micro-catheter for coil embolization. The proposed hybrid stent device is capable of stent-assisted coil embolization while simultaneously providing a flow-diverting effect. The fractal stent device is composed of mesh structures with fine and rough mesh areas. The rough mesh area can be used to insert a micro-catheter for stent-assisted coil embolization. Flow-diverting effects of two fractal stent designs were composed to three commercially available stent designs. Flow-diverting effects were analyzed using computational fluid dynamics (CFD) analysis and particle image velocimetry (PIV) experiment. Based on the CFD and PIV results, the fractal stent devices reduce the flow velocity inside an aneurism just as much as the commercially available flow-diverting stents while allowing stent-assisted coil embolization.

In this paper, we propose a new prototype model of the active guide wire microcatheter whose bending has two degrees of freedom. The design and fabrication methods of this active microcatheter are described. It is 3Fr, 4Fr, 6Fr (1Fr=1/3mm)in diameter and consists of catheter tube and active guide wire with ICPF on its front end as the servo actuator. The bending motion and bending angle of the active guide wire microcatheter have been measured by application of electricity in water and in physiological saline solution. We also modeled this active microcatheter. Experimental results show that the model of the active catheter is reasonable for practical applications. By using simulators (conditions similar to those of a body cavity), we also carried out simulation experiments in vitro. The experimental results indicate that the proposed active guide wire catheter is applicable to intracavity operations.

Magnetic field has been used for manipulation of micro-robots; in this research we use it for scaffold fabrication. Magnetic sugar particle (MSP) was used as porogen to control pore size, pore structure and pore density in the scaffold. We studied the influence of the strength of magnetic fields for controlling the coating thickness of unmagnetized MSPs during the fabrication of sheet-like scaffolds. The experimental relationship between magnetic flux density and the thickness of MSP layer was illustrated. Furthermore we investigated the infiltration capacity of poly(L-lactide-co-e-caprolactone) (PLCL) which was used as scaffold material on the MSP clusters. 5% and 10% PLCL solutions were employed in the experiments. After polymer casting and removal of the sugar template, spherical pores were generated inside scaffold, the thickness evaluation of a single layer scaffold was carried out and the cytocompatibility experiment of NdFeB powder used in fabrication of MSP was confirmed with human umbilical vein endothelial cells.

Computer based simulation is important for clarifying the hemodynamics in brain aneurysm. Specifically, for endovascular treatments, the effect of indwelling intravascular devices on blood stream needs to be considered. Most recent technology for cerebral aneurysm treatment is related with the use of flow diverters to reduce the amount of flow entering to the aneurysms. In this research, we present a new method for design of flow diverters and fitting them to patient specific vasculature models. This methodology enables to change porosity of the flow diverters as well as their location in the blood vessel. One coiling assist stent and two flow diverters were compared to estimate the effect of flow alteration in aneurysm for treatment of a cerebral aneurysm. From the numerical result, we can conclude that pore density and size of mesh affect the hemodynamics in aneurysm and high density and small size of pore produce reduction effect of pressure and wall shear stress on an aneurysm.

For the development of medical micro-robotics and robotic manipulation of catheter it is necessary to ensure tissue integrity. In-vitro evaluation of tissue manipulation can be achieved using photoelastic stress analysis and vasculature modeling with photoelastic materials. In this research we propose epoxy resin as photoelastic material for vasculature modeling as it has a larger photoelastic coefficient than previously studied materials and it has a young modulus similar to human vasculature. A model of a saccular aneurysm with bleb was built with the purpose of measuring stress overshoots that enable to differentiate embolization techniques according to the respect for tissue integrity. During embolization using a coil with smaller size than the aneurysm dome diameter, an average area of 0.72 mm2 with stress above 90 kPa was measured. This area increased to 0.77 mm2 when the dome was touched with the release mechanism of the coil, and to 0.74 mm2 for embolization with larger size coil. The presented modeling material and measurement technique is useful for tissue respect quantification for micro-mechanisms evaluation.

Approaches in scaffold design must be able to construct appropriate porous structures to obtain desired mechanical strength and biofactor delivery. The controlled assembly of pores inside a scaffold will be very useful in the field of tissue engineering and biology. In this paper, we fabricated magnetic sugar particles (MSPs) as porogen to control pore size, pore structure and pore density in the scaffold fabrication by particulate leaching method. Also a kind of new compound material — magnetic PVA is proposed and fabricated for aligning MSPs on desired positions and improving the layout of pores. In-plane magnetizer was utilized to create a permanent magnetic field with a specific pattern over a magnetic PVA layer. After biomaterial casting and removal of the sugar template, spherical pores were generated inside scaffold. Further preliminary cytocompatibility evaluation experiments of ferrite and NdFeB MSPs in developed scaffold were conducted with human umbilical vein endothelial cells (HUVECs). Fluorescent micrograph of HUVECs attached on the scaffold indicates the proposed method is safe at cell cultivation level.

Simulator based evaluation has been used for medical licensing, intravascular tools evaluation and robotic catheter insertion systems research. However it is need to develop quantitative evaluation methods for the catheter trajectory inside vasculature phantoms. In this study we present two technologies developed for that purpose. First we present models of vasculature made of epoxy resin with higher sensitivity for photoelastic effect than previously used modeling materials. The second contribution for that purpose is a stereovision system for measuring evaluation parameters such as catheter tip motion capture, model deformation and stress within the model at 3fps enabling comparison catheter trajectories and catheter insertion robot control. Models of carotid artery, saccular aneurysm with bleb, aorta arch and giant aneurysm were built using the epoxy resin. And for the robot control using the vision system, from 10 consecutive trials of trajectory reconstruction in a model of carotid artery a success rate of 80% was obtained with feedback control activated.

Biodegradable scaffolds with controlled pore layout and porosity have great significance in tissue engineering for cell penetration, tissue ingrowth, vascularization, and nutrient delivery. Porogen leaching has been commonly used to control pore size, pore structure and porosity in the scaffold. In this paper we focus on the use/development of two magnetically guided porogen assembly methods using magnetic sugar particles (MSPs) for scaffold fabrication. First, a patterning device is utilized to align MSPs following designed templates. Then a magnetic sheet film is fabricated by mixing poly(vinyl alcohol, PVA) and NdFeB powder for steering the MSPs. After poly( l -lactide-co-ɛ-caprolactone) (PLCL) casting and removal of the sugar template, a scaffold with spherical pores is obtained. The surface and the inner structure of the scaffolds are evaluated using light and electron micrographs showing their interconnection of pores, pore wall morphology and porosity. Single layer scaffolds with the size of 8 mm in width and 10 mm in length were constructed with controllable pore diameters in the ranges of 105–150 μm, 250–300 μm and 425–500 μm.

Fluid-structure interaction analysis in Internal Carotid Artery(ICA) are carried out as preparation for validation between the result of numerical simulation and photoelastic stress analysis. In this work, we assume blood vessel as an isotropic elastic medium and the wall's Poisson ratio is 0.45 and Young's modulus is 3.0Mpa. Our study shows various parameter on fluid dynamics of blood flow, such as the velocity profile, wall shear stress distribution, displacement of vessel wall and Mises stress. Blood flow after bifurcation generate vortex flow and decreases flow speed and wall shear stress nearly to 0Pa. This low wall shear stress can accelerate the accumulation of plaque and eventually causes vessel narrowing. Moreover, the maximum wall shear stress and Mises stress is focused on the bifurcation of ICA. These high stress may lead to aneurysm initiation.

It is desirable for endovascular surgery simulation to describe with quantitative data the interaction between the catheter and the blood vessel model wall to make an objective evaluation of the procedure. Photoelastic stress analysis in straight segments of multi-layered models was used for that purpose. In this research we study the error introduced by stress direction on the magnitude measurements, for photoelastic stress analysis. And we propose a scanner for three dimensional visualization of photoelastic stress analysis. As result, we quantified that the maximum contribution of error from stress direction in the first half of the fringe is 2.52% for the stress magnitude measurements. Three-dimensional stress visualization was obtained in segment of straight vasculature with an average error in sample slices of 10.73%, 4.55% and 3.18% for inner pressures of 80, 120 and 160mmHg respectively.

To reproduce blood vessel, we proposed new process for fabricating biodegradable scaffold by powder sintering process. In this process, model for molding scaffold was materialized by rapid prototyping. Biodegradable polymer powder and porogen were dusted to model and heated. So, arbitrary shape scaffold would be fabricated. Also, porosity that influences compliance of blood vessel scaffold would be adjusted by changing ratio of the polymer powder and porogen. We studied fabrication condition of blood vessel scaffold by measuring porosity and Young's modulus when the ratio of the polymer powder and porogen was adjusted. Also, HUVECs were cultured on the scaffold, and the scaffold's biocompatibility was confirmed.

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 mi croparticles were encapsulated in sugar spheres to make th em 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. After removal of sugar particles, ordered array of po res were generated on the surface of sheet-like scaffolds. Ordered pores are also generated in 3D tubular scaffolds by using magnetic force and viscoelasticity of PVA solution. It was confirmed that MSPs leaching method makes it possible to make high porous scaffolds in spite of the thickness of scaffold and the porosity is homogeneous. Finally, the biocompatibility of the developed scaffold was confirmed by the viability of human umbilical vein endothelial cells.

We proposed a fabrication method for multiscale transparent arteriole and capillary vessel models and demonstrated the fabrication of microchannels with circular cross sections φ10 – 500 µm. First, we demonstrated fabrication of φ10 – 500 µm arteriole and capillary vessel block models using photolithography. The circularity of fabricated φ10, 50, and 500 µm microchannels were 84.0%, 61.5%, and 82.3%, respectively. Flow experiments demonstrated that these channels had no leakage. Next, we proposed a fabrication method for φ100 – 500 µm arteriole membrane models, which connect larger membrane models and smaller block models. These models were prepared with grayscale lithography and a wax and PVA (polyvinyl alcohol) mixture material. The proposed approach overcame the brittleness of a previous sacrificial model fabricated by ink jet rapid prototyping. The membrane model had a circular cross section with a channel circularity of 90%. Finally, we succeeded in making transparent membranous and block arteriole model with which we can simulate blood circulation.

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Akinori Kagawa, Makoto Negoro, Kazuyuki Takeda, and Masahiro Kitagawa, Review of Scientific Instruments 80, 044705 (2009) and may be found at https://doi.org/10.1063/1.3123346., To advance static solid-state NMR with hyperpolarized nuclear spins, a system has been developed enabling dynamic nuclear polarization (DNP) using electron spins in the photoexcited triplet state with X -band microwave apparatus, followed by static solid-state nuclear magnetic resonance (NMR) experiments using the polarized nuclear-spin system with a goniometer. In order to perform the DNP and NMR procedures in different magnetic fields, the DNP system and the NMR system are spatially separated, between which the sample can be shuttled while its orientation is controlled in a reproducible fashion. We demonstrate that the system developed in this work is operational for solid-state NMR with hyperpolarized nuclear-spin systems in static organic materials, and also discuss the application of our system.

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.

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.

In this study, we succeeded in fine construction of the PLCL (poly-L-lactide-cocaprolactone) scaffold with micrometer range resolution using photolithography. PLCL is a biodegradable polymer which is used as a material of the scaffold to reproduce the blood vessel. Photolithography known as a technique of microfabrication was used for the processing of PLCL. By this technique, we fabricated a sheet-like PLCL scaffold which is patterned straight line ditches. Laminating the sheet-like scaffold, we fabricated microchannels in the PLCL scaffold. By the attachment of HUVECs in the channel, biocompatibility of the sheet-like PLCL scaffold was confirmed. It is expected to evaluate the behavior of cells in the scaffold.

We have been developing scaffolds of three-dimensional (3D) synthetic vascular prosthesis in tailor-made. Human umbilical vein endothelial cells (HUVECs) attached on the inner surface of the scaffold have anticoagulant effects. Asperity structures of the inner surface are important to cell adhesion. It is important to quantify the inner surface asperity condition of the scaffold by observing HUVECs behavior and morphology. For this purpose, we recreated the inner surface profile of the scaffold on a poly(dimethilsiloxane) (PDMS) substrate by microfabrication. We made semiround convex patterns of resist that had 8 mum in diameter and 5 mum high using photolithography, and the concave pattern on the PDMS substrate by printing. We observed HUVECs adhering to the PDMS substrate having concave pattern on it surface. The distribution density of the concaves of the tested pattern is 1600 /mm2 or 40,000 in a 25 mm2 area. In addition, we fabricated a capillary vessel model by photolithography, creating a branched capillary tube model that had 13 mum in diameter. We confirmed that the capillary vessel model had no leakage using a methylene blue solution flow in the channel.

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.

In this work, we propose a multi-layered scaffold made of elastic biodegradable polymer PLCL [1] by salt leaching method [2], which has high porosity at inner layer and high stiffness in outer layer. Before implanting to a damaged position of a patient, scaffolds should be coated with human umbilical vein endothelial cells (HUVECs). (Porous structure is also served as a pathway of sufficient nutrients and oxygen). This inner layer has porosity as means to culture HUVECs on itself, and outer layer has stiffness as means to maintain shape of scaffolds against blood flow as that of blood vessels does. These inner and outer layers were reproduced also as means of intimal layer and internal elastic lamina in human blood vessel especially muscular artery respectively. It was also verified that this fabrication method can be applied to fabricate tri-layered tubular artificial blood vessel scaffold by SEM. Mechanical characterization and porosity of bi-layered scaffolds were evaluated by tensile test and image processing respectively. These parameters were confirmed that can be controllable by adjusting concentration of NaCl for inner layer used in salt leaching method. HUVECs were cultured on the porous structure of bi-layered scaffolds, and the scaffold's biocompatibility was confirmed by viability of cells. Results obtained from these experiments shows we can propose artificial blood vessel scaffold, which has optimal porosity and mechanical strength, not to induce blood clot, intimal hypertrophy and so on in patient's body.

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.

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 (Poly Vinyl 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 3-D vascular shape was constructed. Presented scaffold has the mechanical compliance similar to human blood vessel and provides porous polymer structure appropriate for cell cultivation.

The authors have proposed a new prototype model of a micro-catheter with an active guide wire that has two bending degrees of freedom using an ICPF (ionic conducting polymer film) actuator on its front end as the servo actuator. In this paper, the bending characteristics of the micro-catheter have been measured by the application of electricity in a physiological saline solution. By using simulators (whose conditions are similar to those of a body cavity), the authors also carried out simulation experiments "in vitro" and the contrast experiments of operability between the proposed catheter and conventional guide wire catheter. The experimental results indicate that the proposed micro-catheter is applicable to intracavity operations.

Catheter is one of the medical tools for endovascular surgeries, and it is frequently used for neurosurgical operations. There is, however, a problem that doctors operate a catheter without any force information during their operation, and this problem causes fatigue of doctors. To solve this problem, we propose a micro force sensor for intravascular neurosurgery. This micro force sensor can be installed on the tip of the catheter. The diameter of this sensor is 1.5 mm and length is 12 mm. Using this micro force sensor, we can measure the contact force between the catheter and blood vessels. To express the contact force between catheter and blood vessels is very effective for safe operation. In this paper, we show the structure of the micro force sensor and its characteristics, and also we present the result of an in vivo experiment.

In this paper, we propose a new prototype model of micro active guide wire catheter that has two bending degrees of freedom. The fabrication methods of this micro active catheters (MAC) are described. Prototype models are 3Fr, 4Fr, 6Fr (1Fr=1/3 mm) in diameter and consist of catheter tube and active guide wire with ICPF (ionic conducting polymer film) on its front end as the servo actuator. The bending characteristics of the MAC have been measured by application of electricity in physiological saline solution. By using simulators (whose conditions are similar to those of a body cavity), we also carried out simulation experiments "in vitro" and the contrast experiments of operability between the proposed catheter and conventional guide wire catheter. The experimental results indicate that the proposed MAC is applicable to intracavity operations.

In this paper, we propose a new prototype model of micro-catheter with active guide wire that has two bending degrees of freedom. The design and fabrication methods of this micro active catheters (MAC) are described. Prototype models are 3Fr, 4Fr, 6Fr (1Fr=1/3 mm) in diameter and consist of catheter tube and active guide wire with ionic conducting polymer film actuator on its front end as the servo actuator. The bending characteristics of the MAC have been measured by application of electricity in physiological saline solution. We also modeled this MAC for characteristic evaluation. Experimental results show that the model of the active catheter is reasonable for practical applications. By using simulators (whose conditions are similar to those of a body cavity), we also carried out simulation experiments "in vitro". The experimental results indicate that the proposed MAC is applicable to intracavity operations.

With dynamic nuclear polarization using the photoexcited triplet electron spin (triplet-DNP) of pentacene, nuclear spins can be hyperpolarized even in a low magnetic field at room temperature. Several demonstrations have been performed using bulk crystals. Hyperpolarization in a thin film with triplet-DNP enables new applications, such as general NMR spectroscopy and the polarized target of unstable nuclei. In this work, we succeeded in polarizing 1H spins in a thin film fabricated by the cell method. We obtained a 1H spin polarization of 12.9% using a 7-μm-thick film of \(p\)-terphenyl doped with pentacene in 0.4 T at room temperature. We also obtained a 1H spin polarization of 3.9% in 0.4 T at 150 K using a 60-μm-thick film of trans-stilbene doped with pentacene, whose single crystal cannot be made easily by conventional methods.