Numerical Analysis of Palpation in vivo Using Tactile Sensor Composed of Organic Ferroelectrics

Abstract

Tactile sensors using organic ferroelectrics are promising from the viewpoint of palpation because poly(vinylidene fluoride) [PVDF] tactile sensors have already been developed to evaluate living tissue. Moreover, vinylidene fluoride (VDF) oligomer is a new substance with a smaller number of VDF units than PVDF. As the piezoelectric coefficient of VDF oligomer is great and its film is thin and uniform, it is suitable for preparation of thinner film tactile sensor. On the other hand, in our previous study, we also developed a computer-based surgical simulator to simulate a catheter and guidewire in blood vessels of the brain. In this study, we investigated the palpation in vivo by the tactile sensor composed of organic ferroelectrics using our catheter/guidewire simulator. Using this simulator, the output of the sensor attached on the guidewire tip was calculated when the proximal part of the guidewire model was pushed and pulled. We used the blood vessel model where the friction coefficient or the stiffness was changed partially assuming that these changes occur by a disease. When the friction coefficient between the guidewire and the vessel was large, the sensor outputs became large. When the stiffness of the vessel was small, the sensor outputs became small.

Evaluation of the effect of catheter on the guidewire motion in a blood vessel model by physical and numerical simulations

“…We used a torus-shaped vessel model with an inner diameter of 4 mm. This shape is the same as those used in our previous studies (Takashima et al, 2014(Takashima et al, , 2012(Takashima et al, , 2007(Takashima et al, , 2006. We defined the centerline by connecting a half circle of radius 4 mm.…”

“…In our previous study, we developed a computer-based system to simulate a guidewire in blood vessels using multibody dynamics method (Takashima et al, 2014(Takashima et al, , 2012(Takashima et al, , 2009(Takashima et al, , 2007(Takashima et al, , 2006. The system was able to predict the course of approach to lesions, present numerical results and animations for the quantitative analysis of treatment technique, treatment planning and intra-procedural assistance, and act as a communication tool between patients and the physician.…”

“…For example, in the experiment, the plastic deformation of the guidewire tip occurred because of the large volume of the polymer coating on the distal part of the shape-memory alloy wire. In future studies, we will adopt a friction model based on our previous models (Takashima et al, 2012(Takashima et al, , 2007(Takashima et al, , 2006. The transition of the contact force between the medical devices and blood vessel model along the y-axis from the numerical simulation is shown in Fig.…”

Development of catheter-type tactile sensor composed of polyvinylidene fluoride (PVDF) film

“…As shown in Fig. 6, assuming an elastic cantilever, when a force (W) is applied on the tip of the sensor, the stress (σ 1 ) applied on the cross section of the PVDF film can be expressed as follows [34]:…”

Analysis of rotation angles and motions of the flexible mechanisms in bifurcated blood vessels

“…Meanwhile, a system to simulate the model of catheter and guidewire in vessels has been suggested. [6][7][8] The robotic technology has also been investigated in some relevant research. [9][10][11] A number of types of steerable catheters have been developed, 12 such as smart material actuated catheter, 13 magnetic catheter, 14 hydraulically driven catheter, 15 and pullwire catheter.…”