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 traumas. These damages are mainly caused by excessively forceful manipulation from 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. However, the existing soft grippers pose barriers to be extended for 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 over-gripping 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. The cadaver experiments, rodent experiments and histopathological studies are conducted to validate that the new surgical gripper system is capable of completing the required digital nerve manipulation in digital nerve repair surgery and exhibits very low disruption to the nerve tissues.

Crush injury of nerves is a common condition but the biomechanical integrity of the human peripheral nerve after crushing is unknown. This study aims to investigate the impact of crush injury on human digital nerves based on different compressive forces. Twenty digital nerves were harvested from three fresh-frozen cadaver hands. The original diameters of proximal, middle and distal end of nerve segment were measured. The midst of each digital nerve was compressed by a customized mechanical system, at 1N, 3N and 5N for 30sec. The diameters were measured again within 1 minute after the nerve crush test was performed. The digital nerve was then subjected to biomechanical test to measure its ultimate tensile strength, stiffness, maximum stress and strain. Deformity of digital nerve was computed based on the diameter of middle nerve segment before and after crush test. No significant difference was found in between groups for ultimate tensile strength (p=0.598), stiffness (p=0.593), maximum stress (p=0.7) and strain (p=0.666). The deformity of nerves under the compression of 1N, 3N and 5N was computed at 72.1%, 54.2% and 45.9%. The effect of compression on the deformity of nerves was statistically significant (p<0.001). It was found that the compressive forces have no impact on the biomechanical integrity of peripheral nerves but the deformity of nerves could be severely caused by low compressive force. It is suggested that the management of nerve crush injury shall be taken immediately and focus on neurophysiological function and degeneration of nerves for a crush with low compressive force and short duration.

Forceps are essential tools for digital nerve manipulation during digital nerve repair surgery. However, surgeons have to operate forceps with extreme caution to prevent detrimental post-operative complications caused by over-gripping force. Their intrinsically safe characteristics have led to the increasing adoption of soft robotics in various biomedical applications. In this paper, a miniaturized hybrid soft surgical gripper is proposed for safe nerve manipulation in digital nerve repair surgery. This new surgical gripper includes a soft inflatable actuator and a gripper shell with a hook-shaped structure. The ability to achieve a compliant grip and safe interaction with digital nerves is provided by the inflated soft pneumatic actuator, while the rigid hook retractor still allows surgeons to scoop up the nerve from its surrounding tissues during surgery. The performance of the proposed surgical gripper was evaluated by the contact/pulling force sensing experiments and deformation measurement experiments. In the cadaver experiments, this new surgical gripper was able to complete the required nerve manipulation within the limited working space. The average deformation of the digital nerve with an average diameter of 1.45 mm gripped by the proposed surgical gripper is less than 0.22 mm. The average deformity is less than 15% of its original diameter.

Pulse wave velocity (PWV) is a useful biomarker in the monitoring and risk stratification of various cardiovascular diseases including hypertension. The current gold standard for non-invasive measurement is carotid-femoral PWV (cfPWV) measurement via direct tonometry. However, cfPWV provides only a global PWV measure, which emphasises the need for an alternative capable of local PWV assessment. There are several alternatives for local PWV measurement proposed in the literature and one promising alternative is ultrasound, which offers good penetration depth, accessibility, and a relatively low cost, making it well-suited for non-invasive, real-time acquisition of haemodynamic parameters for PWV estimation. This paper aims to evaluate the different approaches for ultrasound-based acquisition while considering technical and physiological constraints to optimise the accuracy, reliability, and reproducibility of the parameters collected for estimation. In particular, this paper focuses on the flow-area (QA) and lnDiameter-velocity (lnDU) methods, which require local area and velocity data for PWV estimation. Accordingly, this paper discusses the use of ultrasound imaging in vessel data acquisition, highlights various challenges and considerations to be managed during acquisition and processing, outlines the different ultrasound-based imaging modalities for acquiring area and velocity data, and compares the simultaneous and non-simultaneous acquisition of data for PWV estimation.

Pulse Wave Velocity (PWV) is a useful biomarker in the monitoring and risk stratification of various cardiovascular diseases including hypertension. The current gold standard for non-invasive is carotid-femoral PWV (cfPWV) measurement via direct tonometry. However, cfPWV is limited as it can only provide global and not local PWV measurement, hence an alternative local PWV measure is needed. One alternative is ultrasound whose good penetration depth, accessibility, low-cost nature makes it an ideal measurement mode for non-invasive, real-time acquisition of hemodynamic parameters to determine PWV. This paper will discuss the use of ultrasound imaging in vessel data acquisition, cover the different ultrasound-based imaging modalities for acquiring area and velocity data, and compare between simultaneous and non-simultaneous data acquisition for PWV estimation.