A hybrid soft robotic surgical gripper system for delicate nerve manipulation in digital nerve repair surgery

In digital nerve repair surgery, handling the digital nerves using traditional forceps requires surgeons to be extremely cautious in order to minimize unintended iatrogenic nerve trauma. These injuries are mainly caused by excessively forceful manipulation with metallic rigid forceps. Soft pneumatic actuators have been increasingly adopted to broaden the biomedical applications of conventional rigid structures due to their inherent excellent compliance and compressibility. Existing soft grippers, however, face barriers to their use in digital nerve repair, due to their large prototype size or limited gripping force. In this paper, a new two-arm hybrid soft surgical gripper system is proposed to reduce the risk of excessive stress to nerves and facilitate surgeons' delicate nerve manipulation in digital nerve repair surgery. It consists of two hybrid soft surgical grippers, two stiffness-tunable positioning arms, and a pedal-based control system. The inflated soft pneumatic gripping actuator is capable of providing compliant gripping and soft interaction with nerve tissues. This can prevent sudden overgripping force stimulation. The ability to position two surgical grippers is provided by two stiffness-tunable arms combining six pneumatic locking actuators. The inflation of the soft pneumatic actuator is investigated using a theoretical model and finite element analysis. Cadaver experiments, rodent experiments, and histopathological studies are conducted to validate that the proposed surgical gripper system is capable of completing required digital nerve manipulations in digital nerve repair surgery and exhibits very low disruption to nerve tissues.