A Novel FBG-Based Sensing Array for Interaction Force Awareness During Colonoscopy

Colonoscopy is the most effective method for colorectal cancer diagnosis, but the lack of force feedback can hamper its safety and acceptance. We developed a novel sensing array based on fiber Bragg grating (FBG) to provide the interaction force awareness between colonoscope and tissue that can improve the safety of colonoscopy. The force-aware array contained several radial force sensing units (RFSUs) and friction force sensing units, which employed the elastic beams to convert the radial and friction forces into the strain on FBG. Such conversions were analyzed through theory and simulation. The force sensors can achieve high sensitivities of 427.62 pm/N for RFSU and 399.62 pm/N for FFSU with the force ranges of 0∼1 N and -1∼1 N, respectively. Experimental results also show that the sensors are capable of conducting good dynamic force tracking with small maximum relative errors of 4.45% for RFSU and 2.52% for FFSU in full force ranges. The proposed sensing mechanisms perform reliable anti-disturbance capabilities to disruptive forces. The bending and temperature effects on them can also be effectively eliminated through additional strain-free FBGs. The insertion experiments on a highly realistic colon simulator and an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ex vivo</i> swine colon further verified the force-aware capability of the sensing array and its potential for clinical colonoscopy.