Maximum Insertion Force Research Articles

A robot-assisted tracheal intubation system based on a soft actuator?

Tracheal intubation is the gold standard of airway protection and constitutes a pivotal life-saving technique frequently employed in emergency medical interventions. Hence, in this paper, a system is designed to execute tracheal intubation tasks automatically, offering a safer and more efficient solution, thereby alleviating the burden on physicians. The system comprises a tracheal tube with a bendable front end, a drive system, and a tip endoscope. The soft actuator provides two degrees of freedom for precise orientation. It is fabricated with varying-hardness silicone and reinforced with fibers and spiral steel wire for flexibility and safety. The hydraulic actuation system and tube feeding mechanism enable controlled bending and delivery. Object detection of key anatomical features guides the robotic arm and soft actuator. The control strategy involves visual servo control for coordinated robotic arm and soft actuator movements, ensuring accurate and safe tracheal intubation. The kinematics of the soft actuator were established using a constant curvature model, allowing simulation of its workspace. Through experiments, the actuator is capable of 90° bending as well as 20° deflection on the left and right sides. The maximum insertion force of the tube is 2N. Autonomous tracheal intubation experiments on a training manikin were successful in all 10 trials, with an average insertion time of 45.6s. Experimental validation on the manikin demonstrated that the robot tracheal intubation system based on a soft actuator was able to perform safe, stable, and automated tracheal intubation. In summary, this paper proposed a safe and automated robot-assisted tracheal intubation system based on a soft actuator, showing considerable potential for clinical applications.

Cutting characteristics of viscoelastic membranes under hypodermic needle insertion

Cutting characteristics of thin membranes and the mechanics of their interactions with sharp aggressors like needles are critical in many industrial and medical applications. In this study, we performed needle insertion experiments to study the cutting behaviour of membranes made with polyethylene (PE) and nitrile butadiene rubber (NBR) and investigated different stages of the procedure by analyzing the needle reaction force. Moreover, using a detailed parametric study, we investigated the effect of different insertion and membrane parameters on the most important features of the insertion process. The results showed that, in most cases, the crack size, maximum insertion force, puncture displacement, kinetic frictional force, and static frictional force increase with the increase of needle diameter, increase of membrane thickness, or inclining of the needle. On the other hand, the effect of the velocity on features of the insertion process is negligible except for the kinetic frictional force which increases with the insertion velocity. We also showed although lubrication cannot considerably change the maximum needle insertion force into thin membranes, it can substantially decrease the puncture displacement and frictional forces. Furthermore, we observed that the maximum insertion force, puncture displacement, and frictional forces for PE are greater than the values obtained for NBR, while the crack sizes obtained for PE are smaller than those for NBR. Additionally, we proposed a combined experimental-numerical approach using finite-element (FE) modelling to calculate fracture toughness. The fracture toughness values obtained for PE and NBR are 6.66 ± 1.16 kJ/m2 and 3.98 ± 0.56 kJ/m2, respectively. We also exploited the developed finite-element model to predict the whole-field membrane deformation and its mechanical stress.

INFLUENCE OF DILATION ON THE STABILITY OF OSTEOCHONDRAL AUTOGRAFTS IMPLANTED IN CADAVERIC HUMAN FEMURS

The clinical success of osteochondral autografts is heavily reliant on their mechanical stability, as grafts which protrude above or subside below the native cartilage can have a negative effect on the tribological properties of the joint [1]. Furthermore, high insertion forces have previously been shown to reduce chondrocyte viability [2]. Commercial grafting kits may include a dilation tool to increase the diameter of the recipient site prior to insertion. The aim of this study was to evaluate the influence of dilation on the primary stability of autografts.Six human cadaveric femurs were studied. For each femur, four 8.5 × 8mm autografts were harvested from the trochlear groove and implanted into the femoral condyles using a Smith & Nephew Osteochondral grafting kit. Two grafts were implanted into dilated recipient sites (n=12) and two were implanted with no dilation (n=12). Insertion force was measured by partially inserting the graft and applying a load at a rate of 1 mm/min, until the graft was flush with the surrounding cartilage. Push-in force was measured by applying the same load, until the graft had subsided 4mm below congruency. Significance was taken as (p<0.05).Average maximum insertion force of dilated grafts was significantly lower (p<0.001) than their non-dilated equivalent [28.2N & 176.7N respectively]. There was no significant difference between average maximum push-in force between the dilated and non-dilated groups [1062.8N & 1204.2N respectively].This study demonstrated that significantly less force is required to insert dilated autografts, potentially minimising loss of chondrocyte viability. However, once inserted, the force required to displace the grafts below congruency remained similar, indicating a similar degree of graft stability between both groups.

A Sleeve-Based, Micromotion Avoiding, Retractable and Tear-Opening (SMART) Insertion Tool for Cochlear Implantation.

In conventional cochlear implantation, the insertion of the electrode array is strongly affected by the local anatomy and human kinematics. Herein, we present a concept for an insertion tool that allows to optimize the insertion trajectory beyond anatomical constraints and stabilizes the electrode array in manual implantation. A novel sleeve-based design allows the instrument to be compliant and potentially protective to intracochlear structures, while a tear-open mechanism allows it to be removed after insertion by simply retracting the tool. Conventional and tool-guided manual insertions were performed by expert cochlear implant surgeons in an analog temporal bone model that allows to simultaneously record intracochlear pressure, insertion forces and electrode array deformation. Comparison between conventional and tool-guided insertions demonstrate a substantial reduction of maximum insertion forces, force variations, transverse intracochlear electrode array movement, and pressure transients. The presented tool can be utilized in manual cochlear implantation and significantly improves key metrics associated with intracochlear trauma. The instrument may ultimately help improve hearing outcomes in cochlear implantation. The versatile design may be used in both manual cochlear implantation and motorized and robotic insertion, as well as image-guided surgery.

Design of three-section microneedle towards low insertion force and high drug delivery amount using the finite element method

A microneedle has been greatly recognized as one of the most promising devices for novel transdermal drug delivery system due to its capacity of piercing the protective stratum corneum with a minimally invasive and painless manner. During the past two decades, although numerous achievements have been made in the structure and material combination of microneedles, they mostly focus on the pharmacology and functionality of microneedles, and little is reported about how to design the shape of microneedles to reduce insertion force and especially improve penetration efficiency. Using the developed finite element method, we designed three-section microneedles (TSMN) with various sizes and evaluated their maximum insertion force, penetration efficiency, drug delivery amount and strength. The simulation results demonstrate that the well-designed TSMN with shaft width of 60 μm exhibits a lower maximum insertion force of 116.68 mN relative to 167.92 mN of conical microneedle and an effective penetration length of 81.6% relative to 71.38% of conical microneedle. Besides, the optimized TSMN with shaft width of 80 μm shows similar maximum insertion force and 2.3 times the drug delivery amount compared to conical microneedle. These excellent properties are attributed to the optimized design of the shape curve of TSMN sidewall. Such results may provide an inspiration of microneedle design for low insertion force and high penetration efficiency.

Experimental and simulation investigation of surgical needle insertion into soft tissue mimic biomaterial for minimally invasive surgery (MIS).

The surgical needle insertion process is widely applied in medical interference. During the insertion process, the inhomogeneity and denseness of the soft tissues make it tough to detect the essential tissue damage, a rupture occurs that contains huge forces and material deformations. This study is very important, as all the above-mentioned factors are very significant for modern invasive surgery so that the success rate of the surgery can increase and the patient recovers smoothly. This investigation intends to perform minimally invasive surgical (MIS) procedures and reduce the living tissue damage while performing the biopsy, PCNL, etc. A fracture mechanics method was analyzed to create a needle insertion model which can estimate the needle insertion force during inset in tissue-like PVA gel. The force model was calculated by needle insertion experimentally, and also estimated the needle tip geometry, and diameter influences the fracture toughness. Validate exp. results with simulation results and other papers. It is observed that needle diameter has a significant effect on fracture toughness, whereas the insertion velocity has a slight impact on the fracture toughness. During the rotational needle insertion process, the winds-up of the gel occurs and the diameter of the hole was increasing with increased rpm. Maximum insertion force was noticed in the 27 G needle at 5 mm/s. The interaction function will be less at the maximum fracture development region.

Pullout Strength of Triply Periodic Minimal Surface-Structured Bone Implants

Porous bone implants, such as triply periodic minimal surface structures (TPMS) bone implants, are thriving due to controllable physical properties, better osseointegration, and customized morphologies. However, the fixation of screws in such bone implants has yet to be discussed. Here, we investigated the insertion and pullout behavior of surgical screws in TPMS bone implants, including the Fisher Koch S and Gyroid solid-networks. We showed that the effective Young's modulus, insertion force, and pullout strength of the TPMS bone implants can be tuned by structural parameters. Our results revealed that the pullout strength is highly correlated with the maximum insertion force for both the TPMS and solid bone implants. Furthermore, the TPMS ones have significantly larger pullout strengths. We quantified the screw stability by the pullout strength to maximum insertion force ratio, which is 6.70±0.68 and 1.60±0.07 for the TPMS and solid bone implants, respectively. The significantly higher pullout strength of the TPMS bone implants results from the different bone failure mechanisms. Therefore, adopting TPMS architectures in bone implants can relieve the force required to place a surgical screw and enhance the screw stability.

Study and experimental investigation of insertion force modeling and tissue deformation phenomenon during surgical needle-soft tissue interaction

Surgical needle insertion is generally used in the current advanced surgery process, particularly in the area of biopsy, MIS or minimally invasive surgery, brachytherapy, etc. During the needle insertion performance into the soft tissue, one of the most important issues is the tissue deformation that affects the needle engagement inside the tissue material. We have presented an energy-based insertion model, and the conical shape of deformed tissue is assumed. The tests are performed on PVA gel samples, and the model is analyzed to determine the tissue deformation volume during needle insertion into soft tissue. The procedures for evaluating the puncture force which creates the deformation of the contact point. With the help of the needle insertion experimental investigation, a geometric model of tissue deformation phenomenon and insertion force was investigated. The active needle-soft tissue contacts are studied, and with the help of the energy-based insertion model, the different factors like strain energy, potential, and dissipated energies are investigated. The tests are completed on the tissue mimic PVA gel samples, and the results show the volume and area of tissue deformation; at the time of initial needle insertion, the maximum tissue deformation arises and during the needle movement in the post-perforation stage, the deformation gradually decreases as the more peripheral work is altered into the vicious and degenerate energies. The maximum insertion force was noticed in 14° bevel angle needle tip and at 3 mm/s needle insertion speed, the volume of tissue deformation was maximum. The maximum deformation of the issue arises at the initial perforate position, and the distortion reduces along with the raises of the needle movement during the post-insertion period as the needle insertion work is converted into vicious and dissolute energies.

Design and analysis of feeder mechanism for buckling prevention in robotic catheterization

Abstract In this study, a novel two-degree-of-freedom active-feeder mechanism with a disposable roller module for buckling prevention of the catheter tube was developed and analyzed. The buckling phenomenon occurs when the flexible part cannot withstand a compressive force. Buckling can be prevented using additional parts that support the long flexible part along the tube; however, these passive-type buckling-prevention mechanisms cannot improve transmissibility in a rotational motion. By contrast, the active-type mechanism can transmit both translational and rotational motion but has a bulky structure due to additional motors, which makes placing the mechanism near the patient difficult. Therefore, to solve the afore-mentioned issues, a compact and clinically practicable design is proposed. The proposed feeder mechanism was developed using two driving-shaft modules that enable simultaneous translational and rotational feeding with the minimum number of motors. Furthermore, to minimize the deformation of the tube and obtain sufficient grip force to replicate surgeons’ operation, the analysis was conducted based on contact mechanics. The maximum insertion force and rotating torque were estimated and verified using the measured static friction coefficient. In addition, we formulated an accurate insertion length model based on the experimental results. Using the proposed feeder mechanism and accurate insertion model, the buckling prevention and elimination performance were verified through the experiment on the robot system.

Insertion mechanics of amorphous SiC ultra-micro scale neural probes

Objective. Trauma induced by the insertion of microelectrodes into cortical neural tissue is a significant problem. Further, micromotion and mechanical mismatch between microelectrode probes and neural tissue is implicated in an adverse foreign body response (FBR). Hence, intracortical ultra-microelectrode probes have been proposed as alternatives that minimize this FBR. However, significant challenges in implanting these flexible probes remain. We investigated the insertion mechanics of amorphous silicon carbide (a-SiC) probes with a view to defining probe geometries that can be inserted into cortex without buckling. Approach. We determined the critical buckling force of a-SiC probes as a function of probe geometry and then characterized the buckling behavior of these probes by measuring force–displacement responses during insertion into agarose gel and rat cortex. Main results. Insertion forces for a range of probe geometries were determined and compared with critical buckling forces to establish geometries that should avoid buckling during implantation into brain. The studies show that slower insertion speeds reduce the maximum insertion force for single-shank probes but increase cortical dimpling during insertion of multi-shank probes. Significance. Our results provide a guide for selecting probe geometries and insertion speeds that allow unaided implantation of probes into rat cortex. The design approach is applicable to other animal models where insertion of intracortical probes to a depth of 2 mm is required.

Experimental study on needle insertion force to minimize tissue deformation in tongue tissue

This study reports on the effects of insertion velocity, needle tip geometry and needle diameter on tissue deformation and maximum insertion force. Moreover, the effect of multiple insertions with the same needle on the maximum insertion force is reported. The tissue deformation and maximum insertion force strongly depend on the insertion velocity and the tip geometry. No correlation was found between the outer diameter and the maximum insertion force for small needles (30G – 32G). The endurance experiments showed no remarkable difference in the maximum insertion force during 100 insertions.

Effect of composite coating on insertion mechanics of needle structure in soft materials

This research aims to study the effect of a composite coating comprised of polydopamine (PDA), polytetrafluoroethylene (PTFE), and activated Carbon on the insertion mechanics of surgical needles in tissues i.e., polyvinyl chloride (PVC) tissue phantom and bovine kidney. A needle insertion and extraction test system was designed and constructed to measure the insertion and extraction forces. It was found that the composite coating on the needle surface decreases the maximum average insertion and extraction forces by 62% and 64%, respectively, when tested in PVC tissue phantom and by 49% and 30%, respectively, in bovine kidney tissue. Additionally, an Atomic Force Microscope study was performed to characterize the surface properties of the coated needles. It was found that the composite coating reduced the friction force on the needle surface by 65.7%. The decrease in these forces is critical in minimizing tissue damage and decreasing needle path deviation or deflection during percutaneous procedures.

A 2-DOF Needle Insertion Device Using Inertial Piezoelectric Actuator

Insertion into delicate tissue, such as retina vein occlusion, cell manipulation, and vitreoretinal injection, poses challenges to surgeons and biomedical researchers due to the high resolution, large movement range, compact structure, and multi-DOF output requirements. In order to meet these requirements, a 2-DOF arched needle insertion device driven by inertial piezoelectric actuator was proposed in this article. This device could perform theoretical unlimited translational movement and full rotation with high step resolution. A prototype was fabricated with compact structure, the length and diameter were 230 and 32 mm, respectively. The experimental tests were carried out, the insertion device output 2.47 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> m and 0.56 mrad step distance with maximum velocity of 382 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> m/s and 200.9 mrad/s under 120 V driving signals, the maximum insertion force of 32 mN was measured. Additionally, a handheld controller with friendly user interface was also developed for open-loop control utilization, which could automatically calculate and generate the required control signals according to the motion command. This device explores the biomedical application of inertial piezoelectric actuator within a compact size, providing a new choice for numerous innovative treatment and biological research involving precision operation.

Implanting mechanics of PEG/DEX coated flexible neural probe: impacts of fabricating methods.

Resorbable coatings are processed on flexible implants to facilitate penetrations. However, impacts of fabricating methods on implantation damage of coated probes are unclear. Herein, photosensitive polyimide (PSPI) based flexible neural implants are fabricated through clean-room technology. Polyethyleneglycol (PEG) - dexamethasone (DEX) coatings are processed through an improved micro moulding protocol in micro channels, fabricated by computer-numerical-controlled (CNC) micro milling, laser machining, and deep reactive ion etching (DRIE), respectively. An in vitro testing system is developed, using maximum insertion force [Formula: see text] and mean region-of-interest strain [Formula: see text] to accurately evaluate effects of the three fabricating methods on implantation damage at different insertion speed. Rat cerebrum, agarose gel, and silicone rubber are used as brain phantoms for tests. Results show that lower insertion speed, and micro channels fabricated by CNC micro milling or DRIE can minimize implantation damage. The decrease of insertion speed from 2.0 mm/s to 0.5 mm/s reduces [Formula: see text] by 76.2% ~85.1% and [Formula: see text] by 11.6% ~14.7%, respectively. Compared with laser machining, CNC micro milling and DRIE ensure dimensional accuracy of the PEG/DEX coating, reducing [Formula: see text] by 20.2% ~51.4% and [Formula: see text] by 8.0% ~11.6%, respectively. Compared with biological rat cerebrum, [Formula: see text] reduces by 5.8% ~25.1% in agarose gel phantom and increases by 7.7% ~21.0% in silicone rubber phantom, respectively. This study improves processing methods of polymer coatings and reveals mechanical difference between current used abiotic brain phantoms and biological brain tissues. Implantation tests establish quantitative relationship among insertion speed, fabricating methods, and implantation damage.

Effect of vibration on insertion force and deflection of bioinspired needle in tissues

The design of surgical needles used in biopsy procedures have remained fairly standard despite the increase in complexity of surgeries. Higher needle insertion forces and deflection can increase tissue damage and decrease biopsy sample integrity. To overcome these drawbacks, we present a novel bioinspired approach to reduce insertion forces and minimize needle-tip deflection. It is well known from the literature, design of bioinspired surgical needles results in decreasing insertion forces and needle-tip deflection from the needle insertion path. This technical note studies the influence of vibration on bioinspired needle to further reduce insertion forces and needle-tip deflection. Bioinspired needle geometrical parameters such as barb shapes and geometries were analyzed to determine the best design parameters. Static and dynamic (vibration) needle insertion tests were performed to determine the maximum insertion forces and to estimate needle-tip deflection. Our results show that introducing vibration on the bioinspired needle insertion can reduce the maximum insertion force by up to 50%. It was also found that the needle-tip deflection is decreased by 47%.

Evaluation of Insertion Forces and Cochlea Trauma Following Robotics-Assisted Cochlear Implant Electrode Array Insertion.

The objective was to evaluate the effect of cochlear implant (CI) insertion technique on electrode insertion forces and intracochlear trauma. We hypothesize that robotics-assisted insertions will reduce insertion forces and intracochlear trauma compared with manual insertions. Variability in CI outcomes exists across patients, implant centers, surgeons, and electrode types. While surgical techniques that reduce electrode insertion trauma are well established, insertion trauma remains one contributing factor to variability in CI outcomes. Previous work demonstrates that micromechanically controlled insertion tools reduce both maximum insertion forces and insertion variability compared with manual insertions. CI electrode insertions were performed either by hand (n = 12) or utilizing a robotics-assisted tool (n = 12) in fresh frozen, human cadaveric cochleae using electrodes from four different CI manufacturers. Electrodes array insertion forces were additionally evaluated in benchtop cochlea models. Following cadaveric insertions, samples were imaged via high resolution x-ray microscopy to evaluate electrode position and intracochlear trauma events based on a modified Eshraghi scale. Electrode array insertions performed by robotics-assisted system showed significantly lower insertion forces and variability. Manual electrode array insertions had a significantly higher overall trauma score of 3.1 ± 2.0 compared with 0.9 ± 1.0 for robotics-assisted insertions. Robotics-assisted insertions had higher rate of basilar membrane elevations while manual insertions showed higher rates of severe trauma events. The robotic-assisted insertion system reduced trauma events associated with CI electrode insertions in cadaveric cochleae compared with manual insertions. Surgical devices which help to precisely and more consistently insert electrodes may improve CI outcomes and hearing preservation.

Parameters optimization for vibration assisted biopsy insertion

Abstract Different sampling parameters have a great effect on the results of vibration assisted biopsy insertion process. Further analysis of the influence degree and rule of each sampling parameter on a single target variable to obtain the optimal parameter combination is essential for guiding clinical application. In this study, vibration assisted insertion experiments were conducted using gel phantom as experimental material. The effect degree of insertion velocity, vibration frequency, needle diameter and tip surface number on the maximum insertion force and fiction force was researched through orthogonal tests. The experimental results were analyzed by the combination of extreme deviation analysis and variance analysis. Single-objective optimization of different insertion process parameters was carried out to obtain an optimal combination of parameters and the influence degree of each test factor on each index. The experiment results show that according to the degree of effect, the sampling parameters affecting the maximum insertion force from large to small are insertion velocity, needle diameter, vibration frequency and the number of the needle tip surface. The affecting the friction from large to small are insertion velocity, needle diameter, number of the needle tip surface and vibration frequency. The verification experiment result show that optimal parameter combination is reasonable in a certain range.

Design, Modeling, and Evaluation of a Compact and Lightweight Needle End-effector with Simple Force-feedback Implementation for Robotic CT-guided Needle Interventions

We present a compact and lightweight two degrees-of-freedom (DOF) needle end-effector to be applied to a teleoperated needle interventional robotic system. The suggested needle end-effector is computerized tomography (CT)-compatible and easy to sterilize. Because the proposed needle end-effector can be attached to a robotic manipulator, the needle can translate into and rotate in the human body. In addition, a 1-axis load cell is attached to the needle end-effector to measure the longitudinal force applied to the needle. With this force measurement, force-feedback ability has been implemented in the entire master-slave robotic system. Basic performance tests of repeatability and maximum insertion force were performed. Several force-feedback experiments to determine free space response and contact response, as well as a discrimination test, were conducted. Through this verification process, the suggested needle end-effector was found to have potential for application in real environments that require robotic CT-guided needle interventions.

Effect of young's modulus of porcine ligamentum flavum on the epidural needle insertion

In order to predict how much the human ligamentum flavum will be deformed and tented during insertion of an epidural needle, experiments with the porcine spines were done to check the effect of Young's modulus of the porcine ligamentum flavum. Porcine ligamentum flavums were harvested with vertebral bones and trimmed in rectangle shape. The epidural needle was inserted at 0.8 mm/s with a linear actuator from perpendicular to stretch direction of the specimens. Reaction force as insertion resistance with a load cell and side view of the specimen and the needle as deformation of the ligamentum flavum with a CCD camera were recorded synchronously. As results, width of vertebral bones related the maximum deformation, while no relation was observed between width of vertebral bones and the maximum insertion force. Young's modulus affected the maximum insertion force. Human ligamentum flavum has longer width of vertebral bones and larger Young's modulus. Thus, larger maximum deformation and higher maximum insertion force for the human ligamentum flavum were predicted.

Force Model for Ultrasonic Needle Insertion

A better understanding of needle-tissue interaction forces when needle is inserted into tissue during injection and minimally invasive surgery can lead to more accurate needle placement, better needle path planning, and better surgical simulation. In this study, a vibratory needle insertion force model is experimentally developed to explore the effect of ultrasonic amplitude on the insertion force. The maximum insertion force is comprised of three forces: tearing force, spreading force, and friction force. Ultrasonic vibration needle insertion experiments are performed on a tissue simulant to measure how vibratory parameters influence friction force, dynamic fracture toughness, and crack length. Results show that with the vibration amplitude changing from 0 to 517.2 μm, the maximum puncture force reduces up to 60.8%, the friction force reduces up to 80.7%, the dynamic fracture toughness of the phantom decreases up to 76.8%, and the crack length increases up to 325.8%. The increase in crack length created by the high amplitude vibration allows for the substantial decrease in frictional force.