Research On Tactile Sensor And Contact Model For Minimally Invasive Cardiac Surgery

Because of the advantages such as minimal trauma, lower risk of post-operation infection and reduced recovery time, Minimally Invasice Sugery(MIS) has got increasingly attention in clinical medical practice. The medical procedures were changed and the level of medical was improved gradually by the development of MIS. However, when the MIS was performed by the surgeons, lack of tactile information may cause larger damage on healthy tissue or even more serious medical errors. So, the lack of tactile informatin is the biggest obstacle for the development of MIS.In this paper, the research aims to suit for MIS of heart and takes a percutaneous catheter MIS for mitral valve regurgitation as the application object. A novel tactile sensor was designed with a concial concave where uniformly distributed piezoresistive materials for minimally invasive heart surgery. In order to analyse the contact model between this tactile sensor and the tissue of heart, the linear viscoelasticity model for the tissue of swine’s heart was developed in General Kelvin model firstly. Then, the contact model between tactile sensor and viscoelastic solids was set up through the correspondence principle between elasticity and viscoelasticity after obtaining the contact model between the tactile sensor and elastic solids. In order to make finite element simulation of the contact problem more reasonable and accurate, the method of interconversion between relaxation modulus and creep compliacne was studied. After that, the Prony parameters of swine’s heart will be used in finite element simulation. In order to certify the validity of the contact model proposed in this paper, the software named ABAQUS was chosen for finite element simulation. At last, five kinds of rubbers were used for doing experiment on this tactile sensor. The effectiveness and feasibility of the tactile sensor in this paper were confirmed through comparing the results of four kinds of testing.The outstanding aspect about this tactile sensor was that it can not only tell the relative hardness but also provide the shear modulus of the pending test tissue. So, it could be used to judge whether there were diseases about tissue in the organ as predictive function. The method adopted by the contact model modeling was also suit for other contact problems between any other structures with concave and viscoelastic or elastic solids. The traditional way that taking rubber as tissue for finite element simulation was replaced by actual Prony parameters about siwine’s heart in this paper, which is more reasonable and accurate. The method also has a reference value for this kind of simulation research.