A Novel, Flexible, Full-Length, Pressure-Sensing Sleeve for Colonoscopes

Colonoscopy is the gold standard for screening and diagnosing colorectal cancers. One of the important factors resulting in an incomplete colonoscopy procedure is direct trauma to the colon due to large forces applied during the insertion of a colonoscope which causes significant pain and discomfort to the patient. Acquiring the necessary skills for performing a successful procedure is technically challenging and requires substantial training. The current learning techniques primarily focus on completing the procedure without realizing the intensity of the pressure transmitted from the colonoscope to the colon wall. In this paper, a novel pressure-sensing sleeve is presented that can be used to sensorize a commercially available adult colonoscope (Olympus CF-H180AL). The sleeve can be used in an interactive simulator-based training environment capable of providing real-time feedback on the pressure transmitted by the scope to the simulator colon. The sensor was designed using flexible PCBs and utilizing the piezoresistive behavior of carbon-filled polymers (CFP). Different CFP materials and measurement circuits were evaluated to select the ideal combination for reliable measurement of pressure values up to 34 kPa, at which perforations of the colon could occur. Care was also taken that the overall increase in the diameter of the colonoscope with the sleeve was not more than 1 mm. The sleeve was designed to cover an axial length of 1150 mm, and the scope remained sufficiently flexible for use with negligible sensitivity to the bending of the scope when no pressure was applied to the sleeve.