Objective To design and verify an implantable dialysis port that enables the central venous catheter to no longer be placed on the body surface,and to study the effect of the central venous catheter's structural design on its performance.Methods The feasibility of the dialysis port was verified by flow and pressure experiments.Four representative catheter structures were analyzed by finite element method.The recirculation rate,flow rate-pressure ratio and proportion of indwelling particles were recorded,and performance differences were analyzed.An experimental platform was built to verify the simulation conclusion,and the fluid flow direction of the arteriovenous cavity was quantified by the salinity measurement method.Results The dialysis port could reach the flow requirement of 300 mL/min under the 45 kPa pressure.The recirculation rate of the measured central venous catheter was between 10.7％and 23.5％,and the residual value of heparin was between 2.3％and 2.8％.The performance of the catheter with bundle mouth,positive position and side hole structure was better.Conclusions The implantable dialysis port can potentially cooperate with central venous catheters to establish a new vascular access approach.The structure of the central venous catheter should adopt the design of bundle mouth,positive position and side hole,which has better recirculation rate and heparin locking performance with low flow rate-pressure ratio.This study provides a theoretical and experimental basis for structural design and clinical selection of the central venous catheter.

Objective To design and verify an implantable dialysis port that enables the central venous catheter to no longer be placed on the body surface,and to study the effect of the central venous catheter's structural design on its performance.Methods The feasibility of the dialysis port was verified by flow and pressure experiments.Four representative catheter structures were analyzed by finite element method.The recirculation rate,flow rate-pressure ratio and proportion of indwelling particles were recorded,and performance differences were analyzed.An experimental platform was built to verify the simulation conclusion,and the fluid flow direction of the arteriovenous cavity was quantified by the salinity measurement method.Results The dialysis port could reach the flow requirement of 300 mL/min under the 45 kPa pressure.The recirculation rate of the measured central venous catheter was between 10.7％and 23.5％,and the residual value of heparin was between 2.3％and 2.8％.The performance of the catheter with bundle mouth,positive position and side hole structure was better.Conclusions The implantable dialysis port can potentially cooperate with central venous catheters to establish a new vascular access approach.The structure of the central venous catheter should adopt the design of bundle mouth,positive position and side hole,which has better recirculation rate and heparin locking performance with low flow rate-pressure ratio.This study provides a theoretical and experimental basis for structural design and clinical selection of the central venous catheter.

Objective:To study the optimal anastomotic angle of end-to-side anastomosis autogenous arteriovenous fistula (AVF).Methods:A case-report and case-series design was used to obtain clinical data on 10 patients with diabetic nephropathy from Department of Nephrology, the 905th Hospital of the Chinese People′s Liberation Army Navy from June 2024 to February 2025. The models of "radial artery-cephalic vein" end-to-side anastomosis in the forearm with anastomotic angles of 30°, 40°and 50°were established. Numerical simulation was used to analyze the blood flow in the model, and to study the effect of different anastomotic angles on blood flow. Wall shear stress (WSS), cross section flow velocity and flow rate, and relative residence time (RRT) were studied in the model. The Whitney test with Holm correction was used to evaluate the difference in the median RRT between the three angle models.Results:At the moment of 0.65 s, the area fraction of low wall shear stress (LWSS) in the 30° model was 7.7%, which was reduced by 2.4% and 3.7% compared to the 40°and 50°models, respectively. At the time of 0.2 s, the area proportions of high wall shear stress (HWSS) in the 30°, 40°and 50°models were 54.4%, 43.9% and 37.4%, respectively. At 0.2 s, the maximum cross section flow velocity reached 4.07, 3.84 and 3.67 m/s for the 30°, 40°and 50°models, respectively. In the cycle, the maximum mean flow velocity for the 30°model reached 1.20 m/s. The mean flow rates of the 30°, 40°and 50°models in the J-5 cross section were 349, 316, and 328 ml/min, respectivly. For patient 6, the area proportions of the RRT>1 region were 11.97%, 14.84% and 15.22% for the 30°, 40°and 50°models, respectively.Conclusions:The optimal anastomotic angle of "radial artery-cephalic vein" for end-to-side anastomosis AVF surgery in patients with diabetic nephropathy is 40°.

Although low temperature plasma ablation technology has significant advantages in clinical applications,its poor stability,high power consumption and thermal injuries to the tissues are still key factors limiting its widespread use.To address these issues,a device that uses bipolar pulses to excite plasma is developed,and it can flexibly adjust its output voltage,frequency and duty cycle,effectively reducing breakdown voltage and power consumption.By conducting simulation and saltwater discharge experiments,the excitation process of plasma is elaborated in detail.Meanwhile,the effects of two different pulse excitation modes on plasma excitation are discussed and compared.The results show that the bipolar pulse excitation mode is advantageous in reducing discharge current and breakdown voltage,and shortening the formation time of the vapor layer,which effectively relieves thermal injuries to the tissues.Finally,the broad application potential of the plasma ablation device is demonstrated in plasma ablation experiments which are conducted at different voltages,with pork as the experimental material.The study provides a new theoretical basis and practical guidance for the application of plasma ablation technology in minimally invasive surgery.

Although low temperature plasma ablation technology has significant advantages in clinical applications,its poor stability,high power consumption and thermal injuries to the tissues are still key factors limiting its widespread use.To address these issues,a device that uses bipolar pulses to excite plasma is developed,and it can flexibly adjust its output voltage,frequency and duty cycle,effectively reducing breakdown voltage and power consumption.By conducting simulation and saltwater discharge experiments,the excitation process of plasma is elaborated in detail.Meanwhile,the effects of two different pulse excitation modes on plasma excitation are discussed and compared.The results show that the bipolar pulse excitation mode is advantageous in reducing discharge current and breakdown voltage,and shortening the formation time of the vapor layer,which effectively relieves thermal injuries to the tissues.Finally,the broad application potential of the plasma ablation device is demonstrated in plasma ablation experiments which are conducted at different voltages,with pork as the experimental material.The study provides a new theoretical basis and practical guidance for the application of plasma ablation technology in minimally invasive surgery.

Objective:To design a novel electromagnetic ejection device for endoscopic suturing to achieve continuous deployment of suture nails.Methods:An electromagnetic ejection device and its accompanying suture nail structure were designed and a prototype was fabricated based on electromagnetic ejection principles. A finite element model of the electromagnetic ejection device was constructed to study the effects of armature-coil center distance and different driving voltages on suture nail ejection speed. An experimental platform for testing electromagnetic ejection velocity was constructed, and a high-speed camera was used to detect the ejection velocity. A platform for the suture embedding experiment was built to measure the effects of different voltages on the inserting speed of suture into the gastric wall tissue. A platform for a suture extraction force experiment was built to evaluate the extraction force of sutures embedded in tissues under different driving voltages.Results:A suture nail structure and electromagnetic ejection device were designed, and a prototype was fabricated. The ejection velocity increased and then decreased with the increase of the armature-coil center distance, and the maximum ejection velocity was 15.81 m/s at the center distance of 18 mm. At this distance, the voltage was linearly related to the ejection velocity, and the experimental values of the staple basically coincided with the simulated values. When the driving voltage was in the range of 150 to 180 V, the suture nails could successfully insert in the tissues, and the 180 V voltage group had a greater insertion depth. The extraction force of the suture nails at 120, 150, 180, and 210 V voltages were (0.49 ± 0.19), (1.14 ± 0.19), (1.23 ± 0.15), and (1.85 ± 0.31) N, respectively.Conclusions:A novel electromagnetic ejection device for endoscopic suturing is proposed that is capable of continuous firing of suture nails. This device provides a new long-distance driving method for intelligent, minimally invasive surgical instruments.

Objective:To design a single-line low-temperature plasma ablation electrode, aiming to solve the problem of uniform, continuous and stable microbubbles generated by conventional electrodes, and improve the ablation and cutting effect of low-temperature plasma.Methods:The structures of low temperature plasma three-wire electrode and single-line electrode were modeled in SolidWorks 2021 3D modeling software, and the prototype was made by 3D printing. The finite element analysis of electric field and temperature field of the two kinds of electrode ablation process was carried out by COMSOL Multiphysics 6.1 software, and the validity and correctness of the finite element simulation model were verified by temperature test experiment, and the ablation effect and plasma excitation process of the two kinds of electrode were compared by tissue ablation experiment and low temperature plasma excitation experiment.Results:The results of finite element analysis showed that the maximum surface temperature of three-wire electrode and single-wire electrode were 70.2 and 63.3 ℃, respectively, and the surface temperature of single-wire electrode was more ideal, and the maximum electric field intensity of the two electrodes was more than 1.0 × 10 7 V/m, which met the electric field condition of microbubble breakdown. The electric field intensity of the two ends of the three-wire electrode was much higher than that of the other regions, while the electric field intensity of the single-wire electrode had no obvious sudden change and fluctuation. The experimental values of the temperature at the electrode surface and a distance of 1 cm on the electrode surface were basically consistent with the simulation values, the degree of fit was good, and the relative error was 3.2%. The highest ablation temperature of single linear electrode on pig fat was 46.8 ℃. After ablation, there was no coking area in morphology, and the tissue cutting depth of 0.5 mm could be reached in 1 s. When connected to the energy platform, microbubbles would occur on the working electrode surface of the single-wire electrode; when 6 ms was electrified, the working electrode surface was completely covered by microbubbles; when 9 ms was energized, the low-temperature plasma was excited and the blue-purple plasma could be seen; when 25 ms was energized, the microbubbles were still regular and stable. Conclusions:A kind of single-line low-temperature plasma ablation electrode is designed, which can produce uniform, continuous and stable microbubbles and achieve better ablation and cutting effect than the traditional electrode.

Objective:To study the effects of various parameters in the structural design and usage methods of insulin pen needles on their performance.Methods:Twenty-one conventional needles and five self-destructive needles were selected. A testing machine was used to clamp the needle and make it vertically puncture the test material with a constant speed of 50, 100, 150, 200, and 250 mm/min, respectively. The influence of the needle insertion speed on the puncture force was analyzed. The deformation of the needle on the small contact surface and the large contact surface at 4 N was recorded by a Photron high-speed digital camera. The penetration depth at 1 N and 3 N was measured by an indirect measurement and a direct measurement method, respectively, and the maximum damage width of the damage area was recorded. The tilt resistance of the needle at 6°, 9° and 12° under 2 N pressure was obtained by the testing machine. SPSS 27.0 software was used for statistical analysis of the experimental data, and the LSD multiple comparison method was used for one-way analysis of variance.Results:The difference in puncture force between the needle insertion speed of 50 mm/min and the other four needle insertion speeds was statistically significant (all P < 0.05), while the differences between the other groups were not statistically significant (all P > 0.05). The small contact surface needle was significantly deformed, with a large penetration depth, a large maximum damage width, and low anti-tilting resistance. The large contact surface needle was deformed slightly, with a smaller penetration depth, a smaller maximum damage width, and greater resistance to tilting. Conclusions:The influence of the usage method on the large contact surface of the needle is relatively small. The hexagonal and cross-shaped needle seats have stronger anti-tilt ability than the circular needle seat. The hexagonal needle seat is not easy to change with the rotation axis, and the performance is optimal. In the structural design, the size of the connection part should be reduced, and the appropriate shape of the needle base should be selected.

Objective:To establish and validate a gallstones classification method based on deep learning.Methods:A total of 618 gallstones samples were collected from East Hospital Affiliated to Tongji University, and 1 023 high-definition cross-sectional gallstones profile images were captured to construct a cross-sectional gallstones profile image dataset. Based on the traditional eight-category gallstones classification method, a lightweight network model, MobileNet V3, was trained using deep learning and transfer learning methods. The classification performance of MobileNet was evaluated using a confusion matrix with metrics such as accuracy rate, precision rate, F1 score, and recall rate. The MobileNet V3 was improved and further validated using accuracy and loss values.Results:The accuracy rate (94.17%), precision rate (94.03%), F1 score (92.96%) and recall rate (92.99%) of the improved MobileNet V3 model were better than other networks. The improved MobileNet V3 model achieved the highest accuracy rate (94.17%) in gallstones profile classification and was validated by the test set. The confusion matrix showed a weighted average of accuracy rate (92.0%), precision rate (92.6%), and F1 score (92.2%) for each category of gallstones.Conclusions:Based on deep learning, a high-accuracy gallstones classification method is proposed, which provides a new idea for the intelligent identification of gallstones.

Objective To evaluate the accuracy of three-dimensional(3D)reconstruction of the gallbladder volume based on computed tomography(CT)images and study the biomechanical changes in gallbladder motility to explore the relationship between gallbladder dynamics and gallstone formation.Methods A method for calculating gallbladder volume based on CT 3D reconstruction of The gallbladder model was proposed and compared with the ellipsoid method.A finite element model of the gallbladder was constructed for fluid dynamics analysis to simulate changes in gallbladder motor function under different angles of convergence between the cystic and common bile ducts and in the presence of gallstones.Results The mean errors of the specific gallbladder model volume and ellipsoid volume of the 50 patients were 7.26％and 25.35％,respectively.During the refilling period,the maximum pressure,deformation,and flow velocity of the pear-shaped gallbladder were significantly higher than those of the gourd-shaped gallbladder.The angle between the gallbladder and common bile duct had little effect on the bile flow pattern,and the maximum bile flow rate was reached at an angle of 120°.The bile flow velocity of the gallbladder with calculus was lower than that of the gallbladder without calculus,and there was a vortex near the calculus.Conclusions Calculating gallbladder volume based on CT 3D reconstruction is more accurate than the ellipsoid method.Compared with a pear-shaped gallbladder,a gourd-shaped gallbladder has lower gallbladder wall contraction,bile flow rate,and poor motor function.The bile flow rate in the gallbladder is slow,which is more likely to lead to the enlargement of gallstones or the formation of new gallstones.