Needle Displacement Research Articles

Modified ventriculoperitoneal shunt applied to temporary external ventricular drainage

External ventricular drainage (EVD) is a common procedure in neurosurgical practice. Presently, the three methods used most often include direct EVD (dEVD), long-tunneled external ventricular drains (LTEVDs), and EVD via the Ommaya reservoir (EVDvOR). But they possess drawbacks such as limited duration of retention, vulnerability to iatrogenic secondary infections, and challenges in regulating drainage flow. This study aimed to explore the use of a modified ventriculoperitoneal shunt (mVPS)—the abdominal end of the VPS device was placed externally—as a means of temporary EVD to address the aforementioned limitations. This retrospective cohort study, included 120 cases requiring EVD. dEVD was performed for 31 cases, EVDvOR for 54 cases (including 8 cases with previously performed dEVD), and mVPS for 35 cases (including 6 cases with previously performed EVDvOR). The one-time success rate (no need for further other EVD intervention) for dEVD, EVDvOR, and mVPS were 70.97%, 88.89%, and 91.42%, dEVD vs EVDvOR (P < 0.05), dEVD vs mVPS (P < 0.05), EVDvOR vs mVPS (P > 0.05). Puncture needle displacement or detachment was observed in nearly all cases of EVDvOR, while no such complications have been observed with mVPS. Apart from this complication, the incidence of postoperative complications was 35.48%, 14.81%, and 8.5%, dEVD vs EVDvOR (P < 0.05), dEVD vs mVPS (P < 0.05), EVDvOR vs mVPS (P > 0.05). Mean postoperative retention for EVD was 14.68 ± 9.50 days, 25.96 ± 15.14 days, and 82.43 ± 64.45 days, respectively (P < 0.001). In conclusion, mVPS significantly extends the duration of EVD, which is particularly beneficial for patients requiring long-term EVD.

Design and performance analysis of a piezoelectric jetting dispensing valve

In order to meet the requirements of high frequency, high precision, and micro-scale dispensing in the field of microelectronics packaging, a piezoelectric jetting dispensing valve based on two-stage displacement amplifying mechanism was proposed. First, the overall structure and working principle of the proposed piezoelectric jetting valve were described. The displacement amplifying mechanism was designed, and the mathematical relationship between the output displacement and the structural parameters was established. In addition, the performance and the structural size of the displacement amplifying mechanism were analyzed and optimized by using the finite element analysis software. The influences of driving pressure, glue viscosity, needle displacement, and other parameters on droplet diameter and jetting velocity in the process of dispensing were simulated and analyzed. In order to obtain the optimal nozzle structure, the changing curves of glue flowing velocity with different nozzle seal forms, nozzle cone angles, and outlet inner diameters were compared and analyzed. Finally, the prototype of the piezoelectric jetting dispensing valve was machined, and experimental study was performed. The influence laws of driving pressure, glue viscosity, driving voltage, and other parameters on the diameter of droplet were explored. The performance of the prototype was evaluated from three aspects of dispensing frequency, consistency, and minimum dispensing droplet diameter. Results show that the highest dispensing frequency is 230 Hz, the deviation of dispensing consistency is ±8.77%, and the minimum dispensing droplet diameter is 0.54 mm. The experimental results verify the high frequency, consistency, and micro-scale dispensing performance of the piezoelectric jetting dispensing valve based on the displacement amplifying mechanism, which provides a reference for the research of piezoelectric high-frequency jetting dispensing.

Mass flow rate control of solenoid-based injectors

This paper presents a mass flow rate control method for solenoid-based injectors in open-loop, that is, without physical sensor feedback. Measuring the mass flow rate in injectors is important because the performance of the injector determines fuel consumption and emissions. While it is possible to perform this control using different types of sensors, this would increase the cost and reduce the reliability. With this study, it was aimed to control the mass flow rate of solenoid-based injectors using continuous switching control to regulate the injector’s needle displacement without using sensors. For this purpose, a solenoid-actuated injector prototype was created. Model-based estimators were used to determine the states of the injector, while a super-twisting sliding mode controller was used to track the desired mass flow rate references. The results of the experiments showed that tracking for sinusoidal, triangular, and square trajectories yielded a mass flow rate percent error of less than 1.06. The proposed open-loop control algorithm can be used to track different mass flow rate references in internal combustion engines.

An experimental study on the needle valve motion characteristics of high pressure natural gas and diesel co-direct injector

To reveal the gas needle valve dynamic characteristics of the high pressure natural gas and diesel co-direct injector, an innovative non-intrusive needle valve motion characteristics measurement method is proposed. The influence of needle valve movement on injection rate is investigated, and the effect of diesel pressure fluctuation on needle lift process is revealed. The results indicated that the lifting speed of the needle increases with the increase of gas injection pressure. Under the same injection pressure, the displacement curve of the needle valve changes from triangle to trapezoid with the increase in energizing time. Due to the change of the gas flow throttle position, the injection rate does not correspond linearly with the needle displacement curve. In the process of needle upstroke, there are two different velocities in the rising process of the injection rate. Furthermore, in the diesel system, the compression wave reflected from the common rail has a significant influence on the needle dynamic characteristics and injection rate which becomes more obvious with the decrease in injection pressure. Under the action of reflected compression wave, the moment delay of needle reaching the maximum position can reach 0.6 ms, and the gas injection mass can be reduced by 16%.

Evaluation of design and insertion analysis of a conical shaped polymeric based microneedle for transdermal drug delivery applications

Transportation of drug through parental routes are conventionally followed through hypodermic injection methods, where hypodermic injections are administered into the human skin for drug release. However, there are some issues observed when these hypodermic needles are being used, there are instances where the needle is being inserted leaves some needle fractures in the skin. To cater to the issue scientific researchers are voraciously working on designing and developing polymeric type of microneedle structures for various medical diagnostic applications for glucose monitoring, drug delivery, and other applications. This article presents the structural design of a conicalshaped polymeric microneedle and the insertion force while being pierced into the skin. Simulations at different insertion angles on microneedle are analyzed by arriving with total needle displacements in the process of insertion. The von mises stress is also analyzed with applied force at different insertion angles resulted in incremental change in stress exerted by the microneedle. The resultant stress is below the yield stress which makes the microneedle pierce into the skin without breakage.

A sensorized needle guide for ultrasound assisted breast biopsy.

One in every eight women will get breast cancer during their lifetime. Therefore, the early diagnosis of the lesions is fundamental to improve the chances of recovery. To find breast cancers, breast screening using techniques such as mammography and ultrasound (US) imaging scans are often used. When a lesion is found, a breast biopsy is performed to extract a tissue sample for analysis. The breast biopsy is usually assisted by an US to help find the lesion and guide the needle to its location. However, the identification of the needle tip in US image is challenging, possibly resulting in puncture failures. In this paper, we intend to study the potential of a sensorized needle guide system that provides information about the needle angle and displacement in respect to the US probe. Laboratory tests were initially conducted to evaluate the accuracy of each sensor in controlled conditions. After, a practical experiment with the US probe, working as a proof of concept, was performed. The angle sensor showed a root mean square error (RMSE) of 0.48 degrees and the displacement sensor showed a RMSE of 0.26mm after being calibrated. For the US probe tests, the displacement sensor shows high errors in the range of 1.19mm to 2.05mm due to mechanical reasons. Overall, the proposed system showed its potential to be used to accurately estimate needle tip localization throughout breast biopsies guided by US, corroborating its potential clinical application. Clinical relevance - Potential for clinical application where precise needle localization in ultrasound image is required.

A framework to optimize spring-driven autoinjectors

The major challenges in the optimization of autoinjectors lie in developing an accurate model and meeting competing requirements. We have developed a computational model for spring-driven autoinjectors, which can accurately predict the kinematics of the syringe barrel, needle displacement (travel distance) at the start of drug delivery, and injection time. This paper focuses on proposing a framework to optimize the single-design of autoinjectors, which deliver multiple drugs with different viscosity. We replace the computational model for spring-driven autoinjectors with a surrogate model, i.e., a deep neural network, which improves computational efficiency 1,000 times. Using this surrogate, we perform Sobol sensitivity analysis to understand the effect of each model input on the quantities of interest. Additionally, we pose the design problem within a multi-objective optimization framework. We use our surrogate to discover the corresponding Pareto optimal designs via Pymoo, an open source library for multi-objective optimization. After these steps, we evaluate the robustness of these solutions and finally identify two promising candidates. This framework can be effectively used for device design optimization as the computation is not demanding, and decision-makers can easily incorporate their preferences into this framework.

Experimental Study on the Effect of Locally Convergent Configurations on the Flow Pattern in PMMA Microchips

The geometries of micro-channel play a key role in forming of digital droplets, and can be real-time or effective controlling methodologies. Local convergence regions are designed in the rectangular cross-section channels on PMMA microchips, in which two-phase coaxial jets are introduced by inserting a syringe needle. The two-phase flow (lubricating oil (continuous phase, flow rate Q c)/deionized water (dispersed phase, flow rate Q d)) is considered. Two geometric control variables, the relative position (needle displacement x) and tapering characteristics (convergence angle α), are naturally adopted to discribe such geometry configurations. The micro-flow under the change of these two parameters is mainly studied in this paper. Four kinds of characteristic flow patterns, namely, sausages, slug, dripping and jetting, are found in the experiment, and their occurring parameters and developing dynamic characteristics are discussed. The experiment shows that the increase of inner needle displacement x can produce higher frequency and finer droplets, which is in consistent with our previous results obtained in round tube experiments and simulations. While increasing the convergence angle α, contrarily, takes opposite effects.

Needle penetration forces into textile prostheses and skin: experimental study

The use of needles in surgical practice goes beyond the general suturing of tissue and stitching. With the ever-increasing role of robotic surgery, it is essential not to underestimate the importance of haptic interaction in the training of needle insertion techniques. Needle interaction with soft tissues is influenced by several factors including the geometrical characteristics of the needle, the speed of insertion, friction and the mechanical properties of the soft tissue. In this study, three types of textile fabrics generally used for medical device purposes were selected, the first of which was a nonwoven nanomaterial, the second a knitted material and the third a woven material. While the shape of the needle insertion force and displacement curves differed between the selected materials and the type of inserted needle, a number of similarities were observed. With respect to the compact materials, i.e. human skin and the nonwoven material, the round-shaped tip needle generated higher insertion force peaks for all the tested samples while, conversely, the diamond-shaped tip needle produced higher insertion peak forces for the more structured, i.e. the knitted and woven materials. The insertion force required for the skin samples was significantly higher than for the other tested (synthetic) materials.

Piercing soft solids: A mechanical theory for needle insertion

In this paper we investigate the mechanical problem of piercing a soft solid body with a needle. This phenomenon is controlled by the critical condition of needle insertion. Needle insertion involves physical and geometrical nonlinearities and a complex failure mechanism. To overcome the complexity of the problem, we describe needle insertion as a sharp transition between two needle-specimen configurations, namely ‘indentation’ and ‘penetration’. The sharp configurational change emerges from a mechanical instability and follows the principle of energy minimum. We describe the needle-specimen system in terms of the force applied to the back of the needle and the axial displacement of the needle tip toward the material. At small needle displacements, the energetically favoured configuration is indentation. Conversely, when the needle displaces beyond a critical threshold, it penetrates the specimen by rupturing its surface. This creates a new energetically favoured configuration: penetration. Our analysis considers a cylindrical needle with a spherical tip, neglects friction and adhesion between the needle and the material, and assumes quasi-static conditions. Despite the mathematical simplicity of our analysis, our theoretical predictions on the needle insertion force have been validated against experiments with surprising accuracy. Our method provides an effective predictive tool, which can be extended to account for different indenter geometry and material behavior.

An experimentally validated dynamic model for spring-driven autoinjectors

This study focuses on developing a predictive dynamic model for spring-driven autoinjectors. The values of unknown physical parameters, such as the heat convection coefficient and the friction force between the plunger and the syringe barrel, are obtained by fitting the experimentally measured displacements of the plunger and the syringe barrel. The predicted kinematics of the components, such as the displacement and velocity of the syringe barrel, agree well with the experiments with a l2-norm error smaller than 10%. The predictions of the needle displacement at the start of drug delivery agree with the experimental measurements with a l2-norm error of 20%. The maximum air gap pressure and temperature decrease with the initial air gap height but increase with the elasticity and viscosity of the plunger and the mechanical stop. The proposed experimentally validated dynamic model can be effectively used for device design optimization as it is not computationally demanding.

Simultaneous needle lift and injection rate measurement for GDI fuel injectors by laser Doppler vibrometry and Zeuch method

Achieving an adequate knowledge of the fuel injector dynamic operation is an important step in the global effort of improving direct injection gasoline engine efficiency while limiting pollutant emissions. In this frame, needle displacement measurement is an important add-on to evaluate the injector actual performances and can be very useful for developing predictive numerical models to support both the component and engine development. In this study the dynamic behavior of a GDI injector was investigated by the simultaneous measurement of injector needle lift and of the resulting injection rate. With this methodology, the needle displacement is measured by laser Doppler vibrometry, while the injector is tested by an injection analyzer based on the Zeuch method. The vibrometer laser beam points on the needle back surface, passing through a quartz window allowing the fuel pressurization and the normal injector operation. The analysis of the simultaneously acquired needle displacement, injection rate, fuel inlet pressure and current time-history profiles allows a complete insight in the injector dynamic operation. The pressure effect on the needle dynamics was assessed with a detailed analysis of the opening and closing transients; further, multiple actuation strategies were analyzed focusing on the influence of dwell time on the injector dynamics evidencing how the resulting injection rate profile is affected by the needle inertia and by the pressure wave propagation along the fuel line.

Large eddy simulation of a double-injection cycle and the impact of the needle motion on the sac-volume flow characteristics of a single-orifice diesel injector

Study of the flow within diesel injector has gained in importance over the years as several authors have reported that the injector flow in the sac volume highly influenced the nozzle-flow characteristics at low lifts. Few studies have, however, characterized the sac volume and its dynamics. Thus, this paper reports on a numerical characterization of the needle displacement effects (static vs dynamic) on the internal flow of a sac-volume, single-hole diesel injector. To this end, a transient double-injection “closing-opening-closing-opening” cycle was simulated with a monophasic incompressible CFD model in combination with a moving mesh strategy to capture axial needle displacement. A large eddy simulation (LES) approach was chosen to gain better insight into the complexity of this unsteady turbulent flow. The emphasis of the paper is on the dynamic effects of needle movement on the sac flow, while static needle LES results are also shown to illustrate differences. The main findings reported herein are that the dynamic model shows a hysteresis effect associated with the needle motion between opening/closing phases. Quantitatively, the transient needle movement caused a difference in mass flow rate between the sac entrance and exit that was found to reach a maximum of [Formula: see text]. The hysteresis effect was found to be more pronounced at low needle lifts; both static and dynamic models seem to have performed similarly at very high needle lifts. Qualitatively, the LES sac-volume flow representations revealed a fuel jet attachment/detachment with needle movement, while static partial-lift simulations always predict an attached fuel jet. Further analysis of sac vortex dynamics revealed a high-energy vortex-structure breakdown just before the nozzle entrance that could help explain the higher turbulence production reported in the literature, both experimentally and numerically, at low needle lifts.

Reducing the Collision Damage Done to the Tips of Steel Needles during Integrated Piercing by Using Shape Optimization with Feature Selection

Recent research has shown that, during integrated piercing, the yarn tension can displace the needles from the centers of the holes in the piercing template. To reduce the damage done to the needle tips when the needles and the hole walls collide when the needle displacement is too large, this paper proposes a method for optimizing the needle shape that satisfies the strength constraint while targeting minimum needle displacement. First, the optimal objective function and strength constraint conditions for the tip displacement of the integrated puncture needle are established, which are affected by many factors. Then, the feature selection method of machine learning is used to reduce the dimensionality of the objective function after data reduction, and the feasible region of key features is reduced to avoid falling into the local best point in the optimization iteration. Finally, machine vision is used to measure experimentally the tip displacement of a needle array. The results show that the average tip displacement is reduced by 18.16–31.42% and the collision risk is reduced from 43.14% to 5.54%. It shows that the optimization method of needle shape based on feature selection is effective for reducing needle tip impact damage during integrated piercing.

Development of a Piezo-Driven Liquid Jet Dispenser with Hinge-Lever Amplification Mechanism.

Owing to the quick response, compact structure, high precision, huge blocking force generation, and ease of operation, piezoelectric actuators are urgently being adopted in the field of advanced dispensing for jetting performance improvement and fulfillment of precision requirements in microelectronics packaging, adhesive bonding, and miniaturization industry. This research focuses on the fundamental design and development of a piezo-electrically driven compact fluid dispenser using the principle of a class-one lever for amplification of needle displacement, and enhancement of application areas of the developed jet dispenser. Using fundamental lever principle, geometry-based modelling is carried out to fabricate a working prototype of a normally closed hinge-lever type dispenser. Preliminary experiments are carried out to witness the workability of the fabricated dispenser to deliver 100 dots of working fluid per second that will provide a novel device for dispensing of various fluids, and the proposed amplification mechanism suits various other piezoelectric applications as well.

Detailed Model of a Common Rail Injector

Abstract This work is about the validation of a Common Rail (CR) injector model. The model describes injector internal behavior in a detailed way, validation is done using dosage measurements and needle lift traces. The model contains fluid dynamic, mechanic and electro-magnetic parts describing all important internal processes. To compare the modelling results against measurement data, three test cases were chosen on a medium duty test engine to represent a wide range of operation points. Dosage measurements were done by averaging the injected mass of 1500 injections, each measurement repeated three times. Needle displacement was measured using an injector equipped with a needle lift sensor in the same operating points. The results of the simulated injector and the measured values showed good conformity both in needle displacement and injected fuel mass, so the model can be a basis for further injector and combustion analyses.

Simulation and Experiment on Droplet Volume for the Needle-Type Piezoelectric Jetting Dispenser.

The needle-type piezoelectric jetting dispenser is widely applied in the microelectronics packaging field, and it is important to control the droplet size to ensure that the droplet jetting process is successful. In this study, we analyzed the influences of system parameters, such as air pressure, nozzle size, needle strokes, and liquid properties, on droplet size and morphology by considering the droplet formation and separation process through a numerical simulation. An experimental platform was also designed to verify the reliability of the simulations and further analyze strategies for controlling the droplet size. We found that the droplet volume can be increased with an increase in air pressure, needle strokes, and nozzle size until the flow-stream or satellite droplets appear. On the other hand, very small values of these parameters will lead to adhesion or micro-dots. A large nozzle and needle displacement should be chosen for the high-viscosity liquid in order to produce normal droplets. The results also show the recommended ranges of parameter values and suitable droplet volumes for liquids with different viscosities, and these findings can be used to guide the droplet volume control process for needle-type jetting dispensers.

A micro-tattooing device for capsule endoscope using a Wood's metal triggering mechanism

The endoscopic tattooing procedure is essential before surgery in the gastroenterology practice. Because conventional tattooing is conducted by injecting biocompatible ink from outside the human body, a conventional tattooing device is not appropriate for use in the Capsule Endoscope (CE). A compact micro-tattooing device with an optimal triggering mechanism which can be enclosed in the CE is required. Therefore, A micro-tattooing device operated by two conical springs with a Wood's metal-based triggering module is proposed. Needle insertion and ink injection to the submucosal layer of the colon is actuated by triggering mechanism #1. When triggering mechanism #2 is activated, the needle is withdrawn to avoid scratching the internal lumen. Each triggering module is activated by the Joule heating of a Ni-Cr wire with low power consumption to accommodate the CE battery's small capacity. The in-vitro and ex-vivo tests were conducted to confirm the feasibility of the tattooing module. In the in-vitro test, the needle displacement was confirmed to be 3.3 mm. Using extracted porcine colon, the total tattooing procedure was conducted, and the injected ink in the submucosal layer was observed by hemisecting the specimen. Conclusively, the device achieved competitive results, both in terms of power consumption and space constraints.

Design and Experiment of a Moving Magnet Actuator Based Jetting Dispenser

Developing actuators to drive high-frequency jetting dispensers in the dispensing technology for electronic assembly applications has become a concern in recent years. This study proposed a new jetting dispenser without a displacement amplification mechanism directly actuated by a moving magnet actuator (MMA) to jet small fluid droplets. In this article, the main geometric dimensions of the dispensing cluster including the needle, chamber, and seat-nozzle follow those of previous studies and existing dispensers to reduce design time. The necessary root-mean-square force applied to the dispenser needle, which is the key value for the MMA design, is calculated in detail. An ANSYS Maxwell finite element analysis (FEA) is used to simulate the MMA thrust force and modify geometric dimensions. The droplet size produced by the proposed dispenser is empirically investigated under various backpressure, operating frequency, needle displacement, and fluid temperature conditions. The experimental results indicated that the jet dispenser driven by the moving magnet actuator stably operated at the maximal operating frequency of 80 Hz. Some errors, such as losing droplets and generating small satellite dots around the main dots, did not occur during the operating process. In addition, the size of the proposal dispenser without the displacement-magnifying mechanism was also significantly reduced. To conclude, the jetting dispenser driven by the proposal moving magnet actuator can operate well at a medium frequency and shows great potential for dispensing technologies.

Highly resolved Eulerian simulations of fuel spray transients in single and multi-hole injectors: Nozzle flow and near-exit dynamics

In high pressure fuel injectors, needle opening and closing transients cause complex off-design fluid dynamics behaviors that profoundly impact the spray and mixture formation processes. These dynamics are completely different from what is known to occur in steady state conditions.In this study, diesel spray transients have been investigated in single-hole and 3-hole nozzles, encompassing internal and external nozzle flow and including needle motion, performing highly resolved (2.5 μm) computational fluid dynamics (CFD) simulations. We focused on end-of-injection (EOI) and start-of-injection (SOI) processes, in order to provide insights in to the physics. The liquid fuel, vapor and gas species are modeled with a single-fluid multiphase mixture approach, with diffuse interface, and with large eddy simulations (LES) of the turbulence. Occurrence of phase change due to cavitation is accounted for, and the spray dispersion is described with a turbulent dispersion model. Detailed needle motion data and orifice internal surface are available from x-ray synchrotron source measurements carried out at Argonne National Laboratory, and shared through the Engine Combustion Network (ECN) community. Simulations are compared against x-ray phase contrast imaging and radiography of the internal and near-exit flow, in addition to optical microscopy data of the near-exit sprays.Simulation results are found to agree well with available experimental data, and are able to realistically capture local and global features. The simulations allow to gain insight into the physics of gas ingestion and dribbles at EOI, for different hole diameters, operating conditions and number of holes. At SOI, timing of liquid appearance out of the injector and spray tip penetration are adequately predicted, by using the EOI flow field as in-nozzle initialization, and by prescribing the measured tip needle displacement with an informed effective valve opening point inferred from the x-ray observations. Lastly, the variation of spreading angle over time is also discussed in detail for the multi-hole case, including hole-to-hole variations. Due to real geometry features and asymmetric needle motion with eccentric components, it is found that the three holes exhibit swirling flows of increasing intensity as the lift decreases, causing the near cone angle to open and spread, in a quasi-hollow cone structure. These features are not observed in axial single-hole injectors because of their relative simplicity and intrinsic symmetry.