Design, Modeling, Fabrication and Testing of a Piezoresistive-Based Tactile Sensor for Minimally Invasive Surgery Applications

Minimally invasive surgery (MIS) has become a preferred method for surgeons for the last two decades, thanks to its crucial advantages over classical open surgeries. Although MIS has some advantages, it has a few drawbacks. Since MIS technology includes performing surgery through small incisions using long slender tools, one of the main drawbacks of MIS becomes the loss of direct contact with the patient's body in the site of operation. Therefore, the surgeon loses the sense of touch during the operation which is one of the important tools for safe manipulation of tissue and also to determine the hardness of contact tissue in order to investigate its health condition. This Thesis presents a novel piezoresistive-based multifunctional tactile sensor that is able to measure the contact force and the relative hardness of the contact object or tissue at the same time. A prototype of the designed sensor has been simulated, analyzed, fabricated, and tested both numerically and experimentally. The experiments have been performed on hyperelastic materials, which are silicone rubber samples with different hardness values that resemble different biological tissues. The ability of the sensor to measure the contact force and relative hardness of the contact objects is tested with several experiments. A finite element (FE) model has been built in COMSOL Multiphysics (v3.4) environment to simulate both the mechanical behavior of the silicone rubber samples, and the interaction iv between the sensor and the silicone rubbers. Both numerical and experimental analysis proved the capability of the sensor to measure the applied force and distinguish among different silicone-rubber samples. The sensor has the potential for integration with commercially available endoscopic grasper.