Research On Mechanical Properties Of Typical Tissue In Needle Biopsy

The final diagnosis of malignant tumors will use a cytological method. Cancer must be diagnosed by removing a sample of tissue from the patient and examined to determine if the tissue is benign or malignant. There are two methods to collect tissue specimen, i.e., needle biopsy and surgical operation. Surgical operation having large trauma and high cost is not usually the first choice. To shorten recovery and to minimize trauma to the patient, biopsy, using fine gauge needles, is preferred.Needle biopsy is a diagnostic procedure in which, a thin, hollow needle is inserted into tissue for sampling of cells that, after being stained, will be examined under a microscope. Because of the complex structure and mechanical properties of soft tissue, the needle biopsy procedures have small tissue sampling and low accuracy. In this paper, the porcine livers are performed as several tests to measure the force response and acquire the mechanical properties.Non-invasive indentation experiments are performed due to the distinct characteristics of soft tissue in the small and large deformation to measure the force response depending on time in various indentation depth and velocities conditions. A Matlab program based on Nonlinear Least Square Method has been created to fit the indentation results. Finite element analysis of indentation test is also present to verify the availability of hyperelastic and viscoelastic model.Uniaxial tensile tests are performed to acquire stress-strain curve which can describe the mechanical properties and the threshold of tissue failure stress. Material evaluation and procedure simulation with ABAQUS are used to confirm the hyperelastic constitutive model (Ogden N4) and its coefficients of tissue in large deformation.Finally cutting experiments with element cutting tools which are parts of the biopsy needle tip are performed to reveal the relationship between the cutting force and the rake angle of needle edge.