Softness sensing probe with multiple acoustic paths for laparoscopic surgery

PURPOSE: Surgeon's tactile sense is restricted during laparoscopic surgery. We aim to develop a softness sensing probe for endometriosis. Identification of the boundary of the lesion through a tactile sensor during laparoscopic surgery can provide an appropriate cut line, reducing excessive cut. METHOD: We expand our acoustic reflection-based sensing to the proposed probe, which has three force-sensing points to measure the softness of the object. The compensation of the sensor posture with the three sensor outputs was additionally proposed. This sensor has a simple structure and no electrical elements in the part inserted into the body. The sensing principle was verified using the theoretical analysis. Fundamental experiment to make the estimation model and evaluation test with the simulated environment were conducted. RESULT: The fundamental experiment showed that different softness can be estimated and that leave-one-out cross-validation resulted that the root-mean-square-error of the softness estimation was 31.5 kPa within the range of 7.5° in the probe posture. Samples which have similar softness as normal and lesioned uterus were used for the evaluation test using laparoscopic box trainer and a general trocar. Six participants operated the sensor, and the results showed that the samples were significantly discriminated by the softness estimated. CONCLUSION: The experimental results showed that the sensor can estimate the softness while compensating the posture and discriminate model samples of normal and lesioned uterus in the simulated environment, indicating the possibility of boundary identification between normal and lesioned tissues during laparoscopic surgery of endometriosis.