In some surgical operations, a needle is inserted into the patient’s brain to perform the necessary manipulations (for instance, a biopsy). In this context, the study of the interaction between the needle and the brain tissue is an important task. One of common ways to perform experimental study of such interaction is through the use brain phantoms. In this work, a series of experiments is performed on indentation of a biopsy needle into a phantom manufactured of the agar gel. During these experiments, the force of interaction between the needle and the phantom tissue was measured for different indentation speeds and depths. An analytical mathematical model is proposed that describes this force. The model takes into account such effects as viscoelastic and plastic properties and relaxation behavior of the material, as well as the presence of a surface film. Parameters of the model are identified based on the obtained experimental data. It is shown that the results of numerical simulation using this model are in good agreement with the experimental data. Such a model is general and can be used not only for solving problems of biomechanics.
