Analysis of expansion within a pressure inflated section of a simplified urethral model

Abstract

Abstract A new inflatable sensor-actuator system is being developed to analyze the in-vivo biomechanical properties of the urethra of a male human. It could provide decision-aids to urologists while treating issues like urethral strictures. Models that could simulate the biomechanical variations of the urethra are important to evaluate the capabilities of the system under development. For the initial study, a simplified axisymmetric Finite Element Method ‘tube’ model was generated. To simulate an ideal inflating actuator (balloon) within this urethra model, a pressure was applied on the inner wall of the tube. From the region over which the pressure was applied, ‘sensor’ measurements were taken from the ‘top’ plane, ‘middle’ plane and a plane lying between these two. The resulting pressure-circumference and pressure-(wall) thickness responses at these measurement planes were determined. A hyperelastic response attributable to biological tissues was obtained. It was found that the resultant circumferential extension and thickness varies at different planes during the actuator inflation. After inflating at the highest chosen pressure, from the initial inner circumference of 25mm, final extensions ranging 45mm to 63mm for the peripheral plane were obtained. Similarly, extensions ranging from 48mm to 68mm were obtained for the other two planes. The pressure-circumference response at the plane lying on the periphery of the inflated region was found to be less compliant than the plane in the center for the model. A range of biomechanical responses were able to be achieved by performing a parametric variation for the chosen mathematical model and geometry in consideration. The study indicates that a larger dataset can be generated to further model a variety of urethral biomechanical responses. These initial simulations provide important information for identification tasks related to the current development. The results show that simulations could be a prospective way to test new sensors prior to real experiments.