The introduction of robotics technology within endovascular surgical procedures has realised accurate catheter navigation and reduced surgeon irradiation. Insufficient force information from the catheter remains a limitation for significant improvement in the performance of these procedures. While recent developments of catheter tip-force measurement sensors have witnessed a notable outcome, packaging complexities and sensor size constraints limit their application. This work presents an approach to catheter tip-force measurement during endovascular surgery simulation. Image processing and photoelasticity are utilized to measure arterial stress and morphological deformation in a carotid artery segment model. Deformation is measured in real-time and conveyed to the user as haptic feedback during tele-operation of a robotic catheter insertion system. A preliminary single user study was completed to realise the potential of force feedback as it is correlated to the level of deformation and stress in the artery model. The results of this haptic feedback are compared with experimental results of the same operator manually inserting the catheter, and also using a computer graphical-user-interface to control the catheter insertion system.

This paper presents a new in-vitro simulator that can simulate the new technology of three-dimensional digital subtraction angiography (DSA) to perform a cerebral aneurysm surgery. Then, propose a new technique for the numerical evaluation of the surgical tools applied within this interventional surgery to aid in the design and selection of surgical instruments. Initially, the in-vitro intravascular simulator was constructed, followed by cerebral aneurysm models that were fabricated with highly sensitive photoelastic materials of epoxy resin. Then reconstruct virtual reality modeling of the blood vessel and catheter to record the position information and realize virtual guidance for training. Meanwhile, conduct image processing of photoelastic effects for numerical evaluations of surgical instruments such as catheter insertion and stent expansion. During the stent expansion experiment, the average stress in the selected region of interest caused by the expansion was calculated and compared with the corresponding value obtained before the expansion. The presented simulator and measurement technique can assist in improving a surgeons skills, quantifying the performance of medical mechanisms, and contribute to 3D analysis of stress distribution. This approach can also provide feedback control for robot assisted endovascular systems.

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 mm2with stress above 90 kPa was measured. This area increased to 0.77 mm2when the dome was touched with the release mechanism of the coil, and to 0.74 mm2for embolization with larger size coil. The presented modeling material and measurement technique is useful for tissue respect quantification for micro-mechanisms evaluation.

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-ε-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.

Quantification of human skills is a challenge for simulator based medical training, particularly for endovascular intervention. For that purpose it is needed to measure different biometric parameters from the user and additionally measure the interaction between endovascular instruments and vasculature models membrane. For that purpose in this research we present an optical sensor for encoding linear and rotational motion of the catheter through the insertion port. Additionally we present two studies for measuring tissue integrity, time to complete a task, reaction time, and wasting motion using two populations of expert and beginner. The optical encoder showed an average error of 0.39mm and 10.78deg. In both studies the presented cyber-physical system is useful to identify the users with qualities closer to the expert among users with low performance.

For the development of artificial intelligent diagnosis for cerebrovascular intervention, it is desirable to forecast the growth of cerebral aneurysms. In order to achieve such purpose, it is needed to evaluate wall shear stress, strain, pressure, deformation and flow velocity in the aneurysm region. In this research, we focus on in-vitro strain and deformation measurements of cerebral aneurysm models, and propose a cyber-physical system, in which a scaled-up membranous silicone model of cerebral aneurysm was built and integrated with a specialized pump for the pulsatile blood flow simulation, and a vision system was constructed to measure the strain on different regions on the model with pulsatile blood flow circulated inside. Experimental results show that both distance and area strain maxima were larger for the aneurysm neck (0.042 and 0.052), followed by the aneurysm dome (0.023 and 0.04) and then by the main blood vessel section (0.01 and 0.014), which were complemented with computer fluid dynamics simulation for the inclusion of wall shear stress, oscillatory shear index and aneurysm formation index. Medical imaging data of the cerebral aneurysm in 2008 and 2011 was obtained. Diagnosis results have concordance with the aneurysm growth in 2011. The presented measurement method offers an option for measuring strain and deformation to be complementary with computer fluid dynamics and photoelastic stress analysis for advanced diagnostic in the endovascular surgery.

Toward to realizing a novel drug delivery system, a simulation system is considered to be important for a future analysis of it. In this paper, a novel, miniature, and energy-efficient bio-mimetic propulsion concept was proposed. The antibody binding technique is developed and used to attach bacteria to liposome's surface for enhancing liposome mobility. Bacteria and liposome are strongly combined through antibody. Consequently, the effect of antibody when bacteria attached to liposome is studied experimentally. The stochastic nature of bacterial propulsion of liposome is investigated experimentally and analytically. It is shown that antibody plays an important role in attaching bacteria to liposome and the liposome with bacteria moved broader compared to the liposome without bacteria. Statistical calculation matches well with experimental data.

This paper reports a magnetic steering method for controlled porogen fabrication of scaffold for blood vessel regeneration. The method described involves generating gradient magnetic field by a combination structure of Helmholtz coils and Maxwell coils to propel particularly prepared magnetic sugar particles (MSPs) moving in fluid environment at desired trajectory and forming a specified 3D shape as templates for particulate leaching. The movement properties of MSP are theoretically analyzed and the corresponding dynamic mechanics model is established. Further the magnetic field distributions inside the combined coils are calculated and optimal control parameters of coils configuration are obtained. Preliminary motion control experiment is also conducted to prove the feasibility of proposed method. The result demonstrates that MSP cluster can be manipulated with average speed of 0.25 mm/s for a cluster of 12 MSPs and 0.116 mm/s for a cluster of 37 MSPs with the proposed coil system and used for improving interconnection of MSP dot patterns.

This paper presents a sensor fusion between intravascular ultrasound (IVUS) and magnetic trackers for constructing the virtual reality three dimensional models of the blood vessels. We propose this approach for vasculature modeling as part of a guidance system relying on augmented reality for assistance during aortic stent graft deploy. This guidance will facilitate the alignment of the holes on the stent graft walls with the renal and mesenteric arteries ramifications. First we studied the disturbances on the magnetic tracker measurements induced by IVUS emitter after assembling the two sensors together. Then we performed a scan with the hybrid probe inside a blood silicone model submerged into a water tank, captured and fused data from both sensors. The dispersion of samples increased less than 1mm in the evaluated locations while the IVUS was activated. This enabled the construction of a three-dimensional model in virtual reality of the blood vessel model relying on the sensor fusion.

Real-time and accurate stress calculation in walls of vasculature is desired to provide catheter insertion robots of feedback control without changing the catheter stiffness and lumen. This feedback source has also applications in endovascular surgery simulation for human skills and medical tools evaluation. For that purpose we consider photoelastic effect, as birefringence produced by light retardation relates with the stress inside the photoelastic materials. In this research a polariscope was designed for urethane elastomer vasculature models, the photoelastic coefficient of urethane elastomer was measured, and the camera system was calibrated to quantify and reduce error of the measurement system. An average error of 3.6% was found for the pressure range of 70-189 mmHg inside the model of urethane elastomer, this enables to calculate accurately stress in vasculature models during Human Blood Pressure Simulation (HBPS). That way we will be able to compare in a closed loop stress produced by HBPS and by the catheter motion when manipulated by a robot.

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.

We proposed a fabrication method for multiscale transparent arteriole and capillary vessel models and demonstrated the fabrication of microchannels with circular cross sections ¿10 - 500 ¿m. First, we demonstrated fabrication of ¿10 - 500 ¿m arteriole and capillary vessel block models using photolithography. The circularity of fabricated ¿10, 50, and 500 ¿m 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 ¿100 - 500 ¿m 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.

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-ε-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.

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 paper, we propose an in vitro patient-tailored biological model of human cerebral artery, an innovative platform for simulating intravascular neurosurgery to evaluate medical robots and devices. This anatomically accurate model reproduces 3-dimensional configuration of individual arteries with an artery-like thin membranous structure made of silicone elastomer. Its modeling resolution is 13 /spl mu/m. Presented modeling methodology also allows constructing any hollow structure, which is suitable for robot evaluations, making use of CAD. Presented model also reproduces the physical properties of arterial tissue with errors less than 5% (that include elastic modulus, poisson's ratio and frictional coefficient). Thus the cerebral arterial model reproduces not only the behavior of arteries caused by surgical operations, but also the dynamic behavior of surgical robots and devices (e.g. elastic deformation and slip/stick motion). Furthermore, we also propose a novel method that allows developers to evaluate 3-dimensional stress condition on arterial wall, which is caused by surgical operations, by making use of the photoelastic effect. As there are almost no realistic hardware platform enough to fairly evaluate medical robots and devices, it should provide an advanced testing environment for developing robots and other various medical equipments, especially for intravascular neurosurgery.

An in vitro soft membranous model of individual human cerebral artery reproduced with visco-elastic behavior, for intravascular neurosurgical simulation, preclinical testing, and testing of medical devices, is presented. The presented arterial model is reproduced with soft visco-elastic tissues, existing around the cerebral artery, in addition to the elastic membranous structure of artery, and constructed based on individual information obtained with medical imaging modality. Its human-like constitution realizes surgical simulation accompanied with realistic feel and visco-elastic structural deformation under actual surgical environment. In this report, we present a production methodology for this anatomically accurate cerebral arterial model. With this methodology, arteries with complicated or high aspect structures are precisely reproducible. We also present a technique to improve its visibility against refraction and reflection that take place on surfaces around arterial model. As the presented arterial model is compatible with current major imaging modalities such as computed tomography (CT), magnetic resonance (MR) and transcranial Doppler (TCD), it should be useful for a wide range of applications, such as hemodynamic study and radiological investigations, as well as surgical simulations.