The main purpose of the study is design of the innovative tool for determination of mechanical properties of soft biological tissues during minimally invasive surgical operations. This applied problem is closely related with fundamental problems of diagnostics of pathological conditions of soft biological tissues by means of the tactile sensor. In this paper, the contact interaction between the tactile sensor and the soft biological tissue is studied. The analysis of the stressstrain state of soft tissue is carried out using the solution of boundary value problem of contact mechanics. As a first approximation, the linear elastic model of biological tissue is used in formulation of the problem of contact interaction between biological tissues and the artificial tactile sensor. A method is proposed for determination of mechanical characteristics of the studied tissue basing on measurement of the air pressure in pneumatic chamber of the sensor and on processing of images of the contact area between the sensor head and the tissue. An approach is developed for measuring the axial displacement of the central point of the sensor head and using this information in the procedure of estimation of tissue properties, which extends the potential of the proposed method. The prototype of the miniature video pneumotactile sensor is constructed and tested. Results of these experiments are in good agreement with results of numerical simulations.