Application of a new tactile sensor to thoracoscopic surgery: Experimental and clinical study

Background. We developed a new tactile sensor that could quantify the hardness of objects as changes in the resonance frequency of the sensor (Δf). We have applied it to thoracoscopic operations for the localization of small invisible nodules in the lung. Methods. When the sensor probe was moved over the lung surface, a Δf curve was depicted on the computer screen. When the sensor tip reached a point directly above a hard object, a sudden upward jump of the Δf curve was evoked. After experimental studies using pigs, the sensor was applied in 8 patients. More recently we produced a needle sensor to distinguish small nodules from bronchi that may evoke similar upward jumps of the Δf curve. Eight nodules and four bronchi in resected human lungs were probed directly using this sensor. Results. In all of the patients, the hardness of various thoracic structures could be quantified. A total of 10 nodules were found using the sensor and resected thoracoscopically. The needle sensor distinguished nodules from bronchi, as the mean Δf of the bronchial walls (−64 ± 45.9 Hz) was significantly higher than that of nodules (−526 ± 168 Hz, p < 0.001). Conclusions. Thoracoscopic detection of small and invisible pulmonary nodules using our new tactile sensor is feasible.