Ultra-soft and highly stretchable tissue-adhesive hydrogel based multifunctional implantable sensor for monitoring of overactive bladder.

A highly stretchable and tissue-adhesive multifunctional sensor based on structurally engineered islets embedded in ultra-soft hydrogel is reported for monitoring of bladder activity in overactive bladder (OAB) induced rat and anesthetized pig. The use of hydrogel yielded a much lower sensor modulus (1 kPa) compared to that of the bladder (300 kPa), while the strong adhesiveness of the hydrogel (adhesive strength: 260.86 N/m) allowed firm attachment onto the bladder. The change in resistance of printed liquid metal particle thin-film lines under strain were used to detect bladder inflation and deflation; due to the high stretchability and reliability of the lines, surface strains of 200% could be measured repeatedly. Au electrodes coated with Platinum black were used to detect electromyography (EMG). These electrodes were placed on structurally engineered rigid islets so that no interfacial fracture occurs under high strains associated with bladder expansion. On the OAB induced rat, stronger signals (change in resistance and EMG root-mean-square) were detected near intra-bladder pressure maxima, thus showing correlation to bladder activity. Moreover, using robot-assisted laparoscopic surgery, the sensor was placed onto the bladder of an anesthetized pig. Under voiding and filling, bladder strain and EMG were once again monitored. These results confirm that our proposed sensor is a highly feasible, clinically relevant implantable device for continuous monitoring OAB for diagnosis and treatment.

Endoscopic surgery robot that facilitates insertion of the curved colon and ensures positional stability against external forces: K-COLON.

BACKGROUND: Although various endoscopic surgery robots developed in previous studies are versatile and have high lesion accessibility, they have limitations in terms of reaching the target lesion through the curved path in the large intestine and providing a stable tasking environment for the operator. METHODS: An endoscopic surgery robot was developed for performing surgery in the large intestine. The robot was easily inserted into the target lesion in the curved colon through the mounted soft actuator and demonstrated high structural stiffness through the insertion of the sigmoidal auxiliary tendons. RESULTS: The robot was able to access the target lesion in the curved colon through teleoperation alone. Further, it was confirmed that the high structural stiffness overtube improved the overall task performance in the user test. CONCLUSIONS: The proposed robotic system demonstrated the possibility and potential of performing advanced endoscopic surgery in the large intestine.

Sigmoidal Auxiliary Tendon-Driven Mechanism Reinforcing Structural Stiffness of Hyper-Redundant Manipulator for Endoscopic Surgery.

The overtube of an endoscopic surgery robot is fixed when performing tasks, unlike those of commercial endoscopes, and this overtube should have high structural stiffness after reaching the target lesion so that sufficient tension can be applied to the lesion tissue with the surgical tool and there are fewer changes in the field of view of the endoscopic camera from this reaction force. Various methods have been proposed to reinforce the structural stiffnesses of hyper-redundant manipulators. However, the safety, rapid response, space efficiency, and cost-effectiveness of these methods should be considered for use in actual clinical environments, such as the gastrointestinal tract. This study proposed a method to minimize the positional changes of the overtube end tip due to external forces using only auxiliary tendons in the optimized path without additional mechanical structures. Overall, the proposed method involved moving the overtube to the target lesion through the main driving tendon and applying tension to the auxiliary tendons to reinforce the structural stiffness. The complete system was analyzed in terms of energy, and the sigmoidal auxiliary tendons were verified to effectively reinforce the structural stiffness of the overtube consisting of rolling joints. In addition, the design guidelines of the overtube for actual endoscopic surgery were proposed considering hollowness, retroflexion, and high structural stiffness. The positional changes due to external forces were confirmed to be reduced by 60% over the entire workspace.

Effect of backlash hysteresis of surgical tool bending joints on task performance in teleoperated flexible endoscopic robot.

BACKGROUND: The tendon-sheath mechanism provides flexibility but degrades the task performance of the flexible endoscopic robot because of the inherent backlash hysteresis problem. Previous studies have only focused on reducing backlash hysteresis. The goal of this study is to identify the backlash hysteresis criteria of surgical tool bending joints to maintain efficient surgical performance. METHODS: A test platform for a surgical tool has been developed that has initial backlash hysteresis under 5° and can adjust the backlash hysteresis intentionally. Performance variation has been investigated in three bench-top endoscopic tasks in which various backlash hysteresis conditions were intentionally adjusted. RESULTS: A clear drop-off in task performance has been observed when the backlash hysteresis of the bending joints was greater than 10° regardless of the type of task and link length. CONCLUSIONS: The backlash hysteresis of surgical tool bending joints should be reduced to at least 10° to maintain efficient performance in robotic endoscopic surgery.