A tactile sensor using the acoustic reflection principle for assessing the contact force component in laparoscopic tumor localization.

Abstract

Localization of an early stage gastric tumor is easily performed in conventional open surgery, whereas it is a difficult procedure in minimally invasive surgery (MIS). A tactile sensor could allow precise resection of the tumor in laparoscopic surgery. The safety of medical tools should be ensured in MIS. Moreover, boundary conditions such as a double-ended beam without a supporting rigid base during tissue palpation were hardly considered. Thus, we suppose that it is informative to assess the normal force and shear force for practical tumor detection considering the boundary condition. In this study, a tactile sensor with normal and shear force measurement functions using the acoustic reflection principle was developed for gastric tumor detection in MIS. The developed tactile sensor was tested using an artificial phantom of the stomach without a supporting rigid base to evaluate the force response of the sensor in intraoperative tumor localization. The developed sensor is safe for human tissue and can be sterilized. The experimental results show that the developed tactile sensor has the capability to measure normal and shear forces. In the gastric tumor detection test, the shear force of the sensor was more stable and highly responsive to the tumor position than the normal force, which is greatly affected by the bending of the tissue during the operation. A two-axis tactile sensor using the acoustic reflection principle was assembled for tissue palpation in MIS. The results showed that the developed sensor is suitable for tumor detection, indicating that the shear force information of the developed sensor is more useful in MIS for early stage gastric tumor localization.