Carlos Tercero

Photoelastic Stress Analysis Error Quantification in Vasculature Models for Robot Feedback Control

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.

Technical skills measurement based on a cyber-physical system for endovascular surgery simulation

Quantification of medical skills is a challenge, particularly simulator‐based training. In the case of endovascular intervention, it is desirable that a simulator accurately recreates the morphology and mechanical characteristics of the vasculature while enabling scoring.

In vitro three‐dimensional aortic vasculature modeling based on sensor fusion between intravascular ultrasound and magnetic tracker

It is desirable to reduce aortic stent graft installation time and the amount of contrast media used for this process. Guidance with augmented reality can achieve this by facilitating alignment of the stent graft with the renal and mesenteric arteries.

Development of biodegradable scaffolds based on magnetically guided assembly of magnetic sugar particles

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 8mm in width and 10mm in length were constructed with controllable pore diameters in the ranges of 105-150 μm, 250-300 μm and 425-500 μm.

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.

Biodegradable porous sheet-like scaffolds for soft-tissue engineering using a combined particulate leaching of salt particles and magnetic sugar particles

Scaffolds serving as artificial extracellular matrixes (ECMs) play a pivotal role in the process of tissue regeneration by providing optimal cellular environments for penetration, ingrowth, and vascularization. Stacks of sheet-like scaffold can be engineered to become artificial ECMs, suggesting a great potential for achieving complex 3-D tissue regeneration to support cell survival and growth. In this study, we proposed and investigated a combined particulate leaching of magnetic sugar particles (MSPs) and salt particles for the development of a sheet-like scaffold. MSPs were fabricated by encapsulating NdFeB particles inside sugar spheres and were controlled using magnetic fields as a porogen to control pore size, pore structure and pore density while fabricating the scaffold. We studied the influence of the strength of the magnetic fields in controlling the coating thickness of the unmagnetized MSPs during the fabrication of the sheet-like scaffolds. The experimental relationship between magnetic flux density and the thickness of the MSP layer was illustrated. Furthermore, we investigated the infiltration capacity of different concentrations of poly(L-lactide-co-ɛ-caprolactone) (PLCL) as a scaffold material on MSP clusters. Following polymer casting and removal of the sugar template, spherical pores were generated inside the scaffolds. Cultivation of NIH/3T3 fibroblasts on the fabricated scaffold proves that the proposed method can be applied in the cell sheet fabrication.

Catheter Insertion Mechanism and Feedback Control using Magnetic Motion Capture Sensor

Autonomous catheter insertion systems are desirables in fields of cardiology and neurology to reduce the use of X-rays during catheter insertion surgeries. A key point to reach an autonomous catheter insertion system is to provide to a catheter insertion mechanism enough information about the catheter tip position and speed to change its motion according to a predefined point in space to choose a path, and according to the catheter tips speed to detect if the catheter is jammed. In this research we propose the use of magnetic motion capture sensor to provide this information feedback to a catheter insertion mechanism. The system was tested inside a silicon solid arterial model, a silicon membranous arterial and ureter silicon membranous models to simulate a catheter insertion surgery in the upper aorta and inside the kidney. The system changed its motion successfully during the insertions along the models depending on the sensor position compared to a software map of the organ model, also automatic reconfigurations of the motion of the system were done using the speed of the sensor as feedback source

Catheter Insertion Reference Trajectory Construction Method Using Photoelastic Stress Analysis for Quantification of Respect for Tissue During Endovascular Surgery Simulation

There is a need to develop quantitative evaluation for simulator based training in medicine. Photoelastic stress analysis can be used in human tissue modeling materials; this enables the development of simulators that measure respect for tissue. For applying this to endovascular surgery, first we present a model of saccular aneurism where stress variation during micro-coils deployment is measured, and then relying on a bi-planar vision system we measure a catheter trajectory and compare it to a reference trajectory considering respect for tissue. New photoelastic tissue modeling materials will expand the applications of this technology to other medical training domains.

Real‐time in vitro intravascular reconstruction and navigation for endovascular aortic stent grafting

Trans‐catheter endovascular stent grafting minimizes trauma and increases the benefitting patient population. However, the alignment between stent graft branches and vasculature branches remains time‐consuming and challenging, and such techniques require a significant amount of contrast agent for imaging.

Photoelastic stress analysis in blood vessel phantoms: three‐dimensional visualization and saccular aneurysm with bleb

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.