Piercing Force Research Articles

A flexible and dissolving traditional Chinese medicine microneedle patch for sleep-aid intervention

About a quarter of the world's population suffers from insomnia, and the number of the insomniacs is gradually increasing. However, the current drug therapy and non-drug therapy sleep-aid methods have certain limitations. In general, the sleep-aid effect of drug therapy is better than that of Non-drug therapy, but western medicine may lead to some side effects and drug abuse. Although the side effects of Chinese Herbal Medicine (CHM) are relatively small, making the herbal decoction is complex and time-consuming. Therefore, exploring a novel sleep-aid method is very significant. In this paper, a flexible and dissolving Traditional Chinese Medicine (TCM) microneedle patch is proposed for sleep-aid intervention. The TCM microneedle patch is a micrometer-scale intrusive object, and the herbal extracts are carried by the patch. The materials, design method, and fabrication process of the microneedle patch have been described in detail. Besides, the mechanical characteristics of the microneedle patch, sleep-aid effect evaluation method, and experimental scheme have been presented. Three microneedle tips with radii of 5 μm, 15 μm, and 22 μm are selected for simulation analysis. Abaqus simulation results indicate that the smaller the radius of the microneedle tip, the smaller the piercing force. Considering that the microneedle should easily penetrate the skin without buckling, that is, the piercing force should be larger than the buckling force, thus 15 μm, instead of 5 μm or 22 μm, is more suitable to be adopted as the radius of the microneedle tip. For the microneedle with the radius of 15 μm, the piercing force is 0.033 N, and the difference between the piercing force and buckling force is 0.036 N. Experimental results demonstrate that the fracture force of the microneedle is about 0.29 N, which is far larger than the piercing force and buckling force. The single-lead EEG signals of the frontal lobe are used to evaluate the sleep-aid effect of the TCM microneedle patch. After sleep-aid intervention on the Anmian and Yintang acupoints using the patches, for most subjects, the ratios of the low-frequency brain wave energies to the high-frequency brain wave energies are increased obviously, indicating that the proposed sleep-aid method is effective.

Safer Motion Planning of Steerable Needles via a Shaft-to-Tissue Force Model

Steerable needles are capable of accurately targeting difficult-to-reach clinical sites in the body. By bending around sensitive anatomical structures, steerable needles have the potential to reduce the invasiveness of many medical procedures. However, inserting these needles with curved trajectories increases the risk of tissue damage due to perpendicular forces exerted on the surrounding tissue by the needle’s shaft, potentially resulting in lateral shearing through tissue. Such forces can cause significant tissue damage, negatively affecting patient outcomes. In this work, we derive a tissue and needle force model based on a Cosserat string formulation, which describes the normal forces and frictional forces along the shaft as a function of the planned needle path, friction model and parameters, and tip piercing force. We propose this new force model and associated cost function as a safer and more clinically relevant metric than those currently used in motion planning for steerable needles. We fit and validate our model through physical needle robot experiments in a gel phantom. We use this force model to define a bottleneck cost function for motion planning and evaluate it against the commonly used path-length cost function in hundreds of randomly generated three-dimensional (3D) environments. Plans generated with our force-based cost show a 62% reduction in the peak modeled tissue force with only a 0.07% increase in length on average compared to using the path-length cost in planning. Additionally, we demonstrate planning with our force-based cost function in a lung tumor biopsy scenario from a segmented computed tomography (CT) scan. By directly minimizing the modeled needle-to-tissue force, our method may reduce patient risk and improve medical outcomes from steerable needle interventions.

Evaluation of 3D Printability and Biocompatibility of Microfluidic Resin for Fabrication of Solid Microneedles.

In this study, we have employed Digital Light Processing (DLP) printing technology for the fabrication of solid microneedle (MN) arrays. Several arrays with various geometries, such as cones, three-sided pyramids and four-sided pyramids, with different height to aspect ratios of 1:1, 2:1 and 3:1, were printed. Post-processing curing optimizations showed that optimal mechanical properties of the photocurable resin were obtained at 40 °C and 60 min. Ex vivo skin studies showed that piercing forces, penetration depth and penetration width were affected by the MN geometry and height to aspect ratio. Cone-shaped MNs required lower applied forces to penetrate skin and showed higher penetration depth with increasing height to aspect ratio, followed by three-sided and four-sided printed arrays. Cytotoxicity studies presented 84% cell viability of human fibroblasts after 2.5 h, suggesting the very good biocompatibility of the photocurable resin. Overall, DLP demonstrated excellent printing capacity and high resolution for a variety of MN designs.

A novel manipulator with needle insertion forces feedback for robot-assisted lumbar puncture.

The use of lumbar puncture for paediatric diagnosis and treatment, such as cerebrospinal fluid sampling and intracranial pressure measurements, is steadily increasing. However, the standard 'blind' technique makes it difficult to attain accurate needle insertion. In this study, we developed a robot-assisted system to improve the precision of needle insertion during lumbar puncture. The manipulator can perform orientation, insertion and rotation of the needle as well as linear motion at targeted locations. We focused on accurately sensing the puncture forces during the needle insertion phase and evaluated the piercing force perception of the operator. The main features of the robot, such as backdrivable joints, physical human-robot cooperation, actuation system with low friction and remote centre of motion mechanism, can enhance overall safety. Experimental results using a lumbar puncture phantom proved that the manipulator could position the needle tip at targeted locations with good accuracy. The data obtained from the test system also showed that the loss of resistance and peak forces for stiff tissues were accurately perceived by the operator.

ECMO implantation training: Needle penetration in 3D printable materials and porcine aorta.

AimPatients with cardiogenic shock or ARDS, for example, in COVID-19/SARS-CoV-2, may require extracorporeal membrane oxygenation (ECMO). An ECLS/ECMO model simulating challenging vascular anatomy is desirable for cannula insertion training purposes. We assessed the ability of various 3D-printable materials to mimic the penetration properties of human tissue by using porcine aortae.Methods:A test bench for needle penetration and piercing in sampled porcine aorta and preselected 3D-printable polymers was assembled. The 3D-printable materials had Shore A hardness of 10, 20, and 50. 17G Vygon 1.0 × 1.4 mm × 70 mm needles were used for penetration tests.Results:For the porcine tissue and Shore A 10, Shore A 20, and Shore A 50 polymers, penetration forces of 0.9036 N, 0.9725 N, 1.0386 N, and 1.254 N were needed, respectively. For piercing through the porcine tissue and Shore A 10, Shore A 20, and Shore A 50 polymers, forces of 0.8399 N, 1.244 N, 1.475 N, and 1.482 N were needed, respectively. ANOVA showed different variances among the groups, and pairwise two-tailed t-tests showed significantly different needle penetration and piercing forces, except for penetration of Shore A 10 and 20 polymers (p = 0.234 and p = 0.0857). Significantly higher forces were required for all other materials.Conclusion:Shore A 10 and 20 polymers have similar needle penetration properties compared to the porcine tissue. Significantly more force is needed to pierce through the material fully. The most similar tested material to porcine aorta for needle penetration and piercing in ECMO-implantation is the silicon Shore A 10 polymer. This silicon could be a 3D-printable material in surgical training for ECMO-implantation.

Rotary Chop: A New Technique for Teaching Chop and Tackling Mature Cataracts.

IntroductionHere we describe a new cataract chop technique that is most valuable for two groups of ophthalmologists: (1) experienced surgeons encountering challenging nuclear fragmentation due to mature cataracts or zonulopathies, and (2) inexperienced surgeons wishing to develop skills necessary for chopping techniques.MethodsWe have termed this new method “rotary chop,” since the partial thickness pilot holes created by the phacoemulsification (phaco) tip around the periphery of the nucleus produce a rotary phone dial appearance on the surface of the cataract. By creating these pilot holes, the surgeon is able to easily place the chopper deep into the body of the nucleus, avoiding the need to apply vertical piercing force to the nucleus.ResultsThe patient in the technical video had a 4+ nuclear sclerosis cataract. The preoperative vision in this eye was counting fingers at 2 feet with no improvement with refraction. On postoperative day 1, visual acuity had improved to 20/80 . By postoperative week 1, best-corrected visual acuity was 20/20 (20/25-2 uncorrected).ConclusionThis method avoids unnecessary zonular stress. Additionally, inexperienced surgeons using this technique during routine cataract surgery are able to quickly master the movements necessary for both vertical and horizontal chop in a safer environment.Electronic supplementary materialThe online version of this article (10.1007/s40123-020-00249-7) contains supplementary material, which is available to authorized users.

Production of thin-walled sleeves on the piercing mill at PAO STZ

The screw piercing of blanks on a two-roller mill with mushroom-shaped rollers is modeled by the finite-element method. That permits calculation of the piercing forces and analysis of its dimensional precision. The models are verified by comparing the calculated and experimental rolling parameters and sleeve dimensions. On that basis, stable rolling of thin-walled 328 × 20.5 and 433 × 26.9 mm sleeves is possible.

An investigation on the energy absorption of aluminum foam core sandwich panel via quasi-static perforation test

Aluminum foams are a novel branch of advanced materials with superior properties. Sandwich structures with aluminum foam core are good energy absorbers. In this paper, mechanical properties and energy absorption of aluminum foam sandwich panels subjected to quasi-static perforation tests with conical-nosed indenter were investigated experimentally. For this purpose sandwich panels consisting of two aluminum face-sheets and a closed cell aluminum foam core were fabricated. Quasi-static perforation tests on fully fixed sandwich panels were carried out by a universal testing machine at a cross head speed of 0.02 mm/s. Force-displacement curves were recorded and peak piercing force and absorbed energy of sandwich panels were calculated accordingly. Effects of foam core density (0.5, 0.6 and 0.7 g/cm3) and thickness of face-sheets (0.6, 1 and 2 mm) and foam core (10, 20 and 30 mm) on the mechanical properties and energy absorption of samples were discussed. The results showed that increasing foam core and face-sheet thickness and foam core density led to more total absorbed energy being achieved and higher piercing force.

Experimental investigation of energy and punch wear in piercing of advanced high-strength steel sheet

The short service life of tools used to pierce advanced high-strength steel sheet (AHSS) is one of the primary concerns of the automotive industry. A high tool wear rate is expected due to high strength of the sheet to be pierced. This work investigated the effects of tool clearances on the quality of pierced holes, the piercing force, the piercing energy, and tool wear in piercing operations of AHSS and carbon steel sheet. The piercing energy was observed to be the major factor affecting tool wear. The energy was high when using a small tool clearance on AHSS. The tool with large clearance piercing AHSS exhibited a similar degree of wear as that piercing the low carbon sheet. A double shear zone on the cutting edge of AHSS was responsible for the high piercing energy, especially the energy required to push the slug through the die hole and that required for the return stroke, and the high wear rate of the piercing tool with small clearance.

Perforation of aluminium foam core sandwich panels under impact loading: A numerical and analytical study

This paper reports the numerical results of the inversed perforation test instrumented with Split Hopkinson Pressure Bar SHPB with an instrumented pressure bar on the AlSi7Mg0.5 aluminium foam core sandwich panels with 0.8 mm thick 2024 T3 aluminium top and bottom skin. The numerical models are developed in order to understand the origin of the enhancement of the top skin loads found under impact loading (paper published by [1]). Numerical predicted piercing force vs displacement curves are compared with experimental measurements (tests at impact velocities at 27 and 44 m/s). The simulation catches all process of the perforation of the sandwich panels (top skin, foam core, and bottom skin). Within experimental scatter, there is a good agreement between numerical predictions and experimental measurements. Virtual tests with different impact velocities up 200 m/s are presented and showed a significant enhancement of the piercing force under impact loading (top skin peak and foam core plateau loads). In order to understand the origin of these force enhancements, any difference of detailed local information between static and dynamic loading is studied and showed that a shock front effect is responsible for the enhancement piercing force. An analytical model using an improved RPPL shock model based a power law densification assumption is proposed to calculate the top skin piercing force. The improved RPPL shock model agrees with the FE results for small velocities and gives better prediction of the piercing force than the RPPL shock model for large velocities (>100 m/s).

Effects of grain size on the sheared surface in micropiercing of austenitic stainless steel SUS304

Over the last decade, development of fine-grained materials and investigation into the effect of different grain sizes on metal forming at the micro-scale have been seen worldwide. There were several technical reports and scientific papers dealing with the quality improvements with use of the ultra-fine grained steel due to the different grain deformations. However, there were few studies concerning effect of the grain size on the sheared surface in micropiercing. In this study, we investigated stability of the sheared surface length of the cross section in micro-pierced holes. The inner diameter of the holes and maximum piercing forces were measured in order to evaluate the effect of the grain size in the micropiercing process. As reducing the material grain size, ratio of the fractured surface and maximum piercing force increased with tendency to tensile strength. However, the ratio of the burnished surface to the fractured surface as well as inner diameter of the pierced holes varied, depending on the grain size of the material. As a result, a suitable grain size should be considered for a micropiercing process.

GEOMETRY, PENETRATION FORCE, AND CUTTING PROFILE OF DIFFERENT 23-GAUGE TROCARS SYSTEMS FOR PARS PLANA VITRECTOMY

To investigate the geometry, penetration force, and cutting profile of 23-gauge trocar systems for pars plana vitrectomy based on their grinding methods in a standardized laboratory setting. In this experimental study, Eleven different commercially available 23-gauge sclerotomy trocar systems were divided into 4 groups according to their needle grinding and deburring: "back" bevel, "spear" bevel, "lancet" bevel, and "spatula" bevel. The normative geometrical data of the trocar systems were systematically analyzed according to nomenclature ISO 7864 and ISO 9626. Force to penetrate a 0.4-mm thick polyurethane foil was measured by a Penetrometer, when the trocar needle was piercing, cutting, and sliding through the foil at different defined loading phases and plotted as a load-displacement diagram. Magnified images of the consecutive cut were taken under a microscope after the entire penetration through the foil. Three physicians used all trocar systems in a masked fashion on human sclera to evaluate the manual penetration force in 30° and 90°. The mean outer diameter of the trocar systems was 0.630 ± 0.009 mm, and the mean outer diameter of the trocars was 0.750 ± 0.013 mm. The mean point length was 3.11 ± 0.49 mm, and the mean length of the bevel was 1.46 ± 0.23 mm. The primary bevel angle was 10.75 ± 0.41°, and the secondary bevel angle was 65.9 ± 42.56°. The piercing forces of the back bevel and spear-pointed trocars/needles were at the same level (0.087 ± 0.028 N). The lancet-pointed needle had remarkable low piercing and cutting forces with 0.41 N (range, 0.35-0.47 N). The spatula bevel tip showed the highest penetration piercing force with 1.6 N (range, 1.59-1.73 N). The back bevel systems induced frequently triangular-shaped incisions, with two nearly rectangular cuts of short length. The spear bevels produced a regular characteristic linear cut. Especially, the lancet blade created straight cut with a linear wound apposition. Spatula trocar systems caused usually an arched accurate incision. The manual force to penetrate the human sclera in an angled and rectangular angle appeared in the surgeons hand lower with a back bevel, lancet, or spear tip, whereas higher with spatula bevel systems. Lancet and back bevel systems show less penetration force of inner needles than the spatula systems. The results of the penetration force experiments correlated well with the manual force on sclera.

On the piercing force enhancement of aluminum foam sandwich plates under impact loading

This article tends to explain the observed piercing force enhancement under impact loading of the sandwich panels, which is made of rate-insensitive aluminum skin sheet and Cymat foam core. Using an elastic–plastic damageable model for the skin and an isotropic foam constitutive model for the core, a numerical model is proposed and validated by the comparison with experimental results. Virtual tests allow revealing that the damage evolution in the skin sheet is strain rate dependent because of the wave propagation effects. Under impact loading, the damage area is larger and it leads to a larger deflection of the skin plate at its breaking. Therefore, the foam cores are more compressed under impact loading and induce the piercing force enchancement of the sandwich.

More evidence of the crucial roles of surface superhydrophobicity in free and safe maneuver of water strider

This letter presents a study of the effect of surface superhydrophobicity on piercing force and detaching force of water strider’s leg when it vertically contact with water surface. We showed that in contrast to the parallel contact of the leg with water at which the piercing force is insensitive to the contact angle which raised much debate on the functions of superhydrophobicity of water strider’s leg, the piercing force of the vertical contact is, however, very sensitive to the contact angle, which then suggests the surface superhydrophobicity is indeed crucial for water strider’s free and safe activities on water surface.

Choosing the shape and dimensions of punches for the operation of piercing on a press

Computer modeling and physical modeling are used to develop a method for choosing the shape and dimensions of a piercing tool based on the engineering problems that need to be solved. Results are given from use of the method to choose the shape and dimensions of tools in relation to the piercing force, the stability of the punches, the flow of metal into a hollow punch, and the removal of defects from continuous-cast semifinished products.

Global Manufacturing: Reconfiguration of Machines in Addressing Changing Customer Requirement Scenarios

The dynamics of customer requirements in the global domain are dictating a need for the reconfiguration of existing conventional manufacturing systems in order to adapt and respond to the changing functional requirements. This study presents the investigation of the feasibility of adapting a hydraulic cam system to a power press for uphill sheetmetal piercing. The surface topography of sheared edges of blanks and slugs was analyzed using Zygo New View 200 Scanning White Light Interferometer. The piercing force in each trial was monitored and analyzed via computer-press interface data acquisition system (DAS). The average piercing force, 10721N, obtained was found to be nearly constant throughout the experimental trials.

A blood sampling microsystem for pharmacokinetic applications: Design, fabrication, and initial results

This paper describes a microsystem for automated blood sampling from laboratory mice used in pharmacokinetic studies. Intended to be mounted as a "backpack" on a mouse, it uses a microneedle, reservoir, and an actuator to instantaneously prick the animal for a time-point sample, eliminating the need for a tethered catheter with large dead volume. The blood is collected by capillary effect through a 31-33 gauge microneedle (250-210 microm OD) into a approximately 1 microL micromachined steel reservoir. The voice coil actuator provides a peak force of approximately 300 mN, which amply exceeds the measured piercing force of mouse skin (i.e., 60-85 mN for a 31-gauge needle with 12 degrees bevel). The sampling system was tested in vitro using a mock vessel with adjustable pressure; the reservoir was filled in <0.15 s by a combination of the capillary effect and blood pressure. The system may also be used to sample interstitial fluid, but the absence of blood pressure makes it necessary to enhance the capillary effect of the needle. This is accomplished by either electropolishing the inner surface to make it more hydrophilic or using a polymer wire insert to increase the surface area. The steel surface of the reservoir is also coated with silicon oxynitride by plasma-enhanced chemical vapor deposition to improve its hydrophilicity. Blood from fresh bovine tissue was collected into the reservoir to simulate interstitial fluid sampling. In vivo tests on live, anesthetized mice resulted in successful collection of blood into the reservoir. The possible integration of the device in microanalytical systems and the device scalability for multisampling are discussed.

Comparative Experimental Evaluation of Guidewire Use in Urology

To evaluate the characteristics and mechanical properties of five different guidewires principally used in urology to provide a guide to the best choice in every situation. This objective was achieved by performing mechanical tests on each guidewire and on the same guidewire in relationship to a real human ureter. Finally, the mechanical properties of a real human ureter were evaluated experimentally. Five different guidewires with a 0.035-in. external diameter were studied to determine their mechanical properties of interest: tip buckling, shaft permanent deformation, guide friction on the human ureter, and the force at which the tip perforated a real human ureter. Nitinol guidewires with hydrophilic coating had the least dangerous tip in the tip buckling and tip piercing force tests and the lowest friction values on the friction guide test. The shaft of the polytetrafluoroethylene-coated guidewires was stiffer on the bending resistance and plastic deformation tests. The ideal endourologic guidewire should be sufficiently flexible and lubricated to negotiate a tortuous ureter and pass possible obstructions. However, high strength against bending is also required when we need to pass a stent or catheter over a guidewire.

Mechanical Behaviour of Cellular Solids and Their Sandwich Panels under Impact Loading

This paper presents a experimental study of the strength enhancement under impact loading of metallic cellular materials as well as sandwich panels with cellular core. A testing method using 60mm diameter Nylon Hopkinson pressure bars is used to investigate the rate sensitivity of various metallic cellular materials as honeycombs, foams. Finally, an inversed perforation test on sandwich panels with an instrumented pressure bar is also presented. Such a new testing setup provides piercing force time history measurement, generally inaccessible. Testing results show a notable enhancement of piercing forces, even though the skin aluminum plates and the foam cores are nearly rate insensitive.

Cellular Structures under Impact Loading

This paper presents a study of the strength enhancement under impact loading of metallic cellular materials as well as sandwich panels with cellular core. It begins with a review of likely causes responsible for the strength enhancement of cellular materials. A testing method using 60mm diameter Nylon Hopkinson pressure bars is used to investigate the rate sensitivity of various metallic cellular materials. In order to identify the factor responsible for the strength enhancement of those materials, an experimental analysis is performed on a model structure which is a square tube made of rate insensitive materials. Significant enhancement is experimentally observed under impact loading, whereas the crushing mode is nearly the same under both static and impact loading. Finally, an inversed perforation test on sandwich panels with an instrumented pressure bar is also presented. Such a new testing setup provides piercing force time history measurement, generally inaccessible. Testing results show a notable enhancement of piercing forces, even though the skin aluminum plates and the foam cores are nearly rate insensitive.