Needle Tip Geometry Research Articles

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.

Microscale engineering of hollow microneedle tips: design, manufacturing, optimization and validation.

Transdermal and intradermal drug delivery utilizing microneedles is an emerging front in painless therapeutics. Drug delivery using hollow microneedles is the most preferred method for delivering generic transdermal drugs in the clinical setup. The needle tip must be extremely short as the drug is administered to sub-millimeter depths. Also, they need to be sharp enough to pierce through the skin with minimal skin flexing. There are multiple challenges in engineering a tip profile that is short and sharp at the same time. Stainless steel (SS) hypodermic needles with the lancet tip profile are ubiquitous in subcutaneous and intramuscular injections. They have long bevel lengths that make them inappropriate as microneedles. Thus, designing a unique tip profile and developing the manufacturing technology for microneedle applications are necessary. This article presents the design and optimization of microneedle tip profiles through analytical models. Further, manufacturing strategies for reliably obtaining designed profiles are discussed. The article concludes with experimental validation of improved piercing performance of the optimized tip profile compared to other tip profiles. The article discusses about tip geometries of stainless steel needles for microneedle applications, where depth of delivery is less than 1 mm. Through series of analyses, the optimum needle tip geometry evolved from single plane bevel (SPB) to hex plane bevel (HPB) progressively improving piercing performance.

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.

Multi-Bevel Needle Design Enabling Accurate Insertion in Biopsy for Cancer Diagnosis.

To obtain definitive cancer diagnosis for suspicious lesions, accurate needle deployment and adequate tissue sampling in needle biopsy are essential. However, the single-bevel needles in current biopsy devices often induce deflection during insertion, potentially causing lesion missampling/undersampling and cancer misdiagnosis. This study aims to reveal the biopsy needle design criteria enabling both low deflection and adequate tissue sampling. A novel model capable of predicting needle deflection and tissue deformation was first established to understand needle-tissue interaction with different needle tip geometries. Experiments of needle deflection and ex-vivo tissue biopsy were conducted for model validation. The developed model showed a reasonably good prediction on the correlation of needle tip type vs. the resultant needle deflection and tissue sampling length. A new multi-bevel needle with the tissue separation point below the needle groove face has demonstrated to be an effective design with an 87% reduction in deflection magnitude and equivalently long tissue sampling length compared to the current single-bevel needle. This study has revealed two critical design criteria for biopsy needles: 1) multiple bevel faces at the needle tip can generate forces to balance bending moments during insertion to enable a low needle deflection and 2) the tissue separation point should be below the needle groove face to ensure long tissue sampling length. The developed methodologies and findings in this study serve as proof-of-concept and can be utilized to investigate various biopsy procedures to improve cancer diagnostic accuracy as well as other procedures requiring accurate needle insertion.

Assessment of needle tip geometry during infusions into a brain phantom gel

Convection-enhanced delivery (CED) is a promising method to deliver therapeutic drugs directly into the brain that has shown limited efficacy, mainly attributed to backflow, in which the infused drug flows back along the needle track rather than forward into tissue. This study evaluates the effect of sharp and blunt needle tips on backflow length under different flow rates via CED. Infusions were performed in a transparent 0.6% (w/v) brain phantom agarose hydrogel. Backflow length was significantly higher using sharp-tip needles for higher flow rates. No significant differences were observed between tip shapes for lower flow rates. In conclusion, sharp-tip needles present limitations for higher flow rates, which are needed to deliver more drug during shortest times.

Abstract No. 504 Ex vivo evaluation of the effect of multiple electrode radiofrequency needle tip convergence on size of ablation zone

Radiofrequency ablation (RFA) is an established therapy for treatment of malignancy in several organs, including the liver. One commonly used system, the Cool-tip Cluster Electrode, uses three parallel needles fixed in a triangular geometry. However, upon insertion, the final geometry of the needle tips can vary. In the case of converging needles, ablation volumes have been anecdotally observed to be smaller than expected. The study objective is to determine whether needle tip convergence significantly affects ablation zone in a bovine liver model. Cool-tip Cluster Electrodes were used to perform RFA in an ex vivo bovine liver using a 3D-printed guide to produce: no, partial or full convergence of the electrode needle tips. Ablation time was 12 minutes. Cone beam computed tomography scans were obtained to verify needle positions. Time to first roll off and period between roll-offs was recorded. Gross pathology was performed to estimate ablation zone volumes. Preliminary results from the initial pilot experiment found partial needle tip convergence decreased ablation zone volume by 6.13 cm3 (40.3%), time to first roll-off by 5.16 minutes (36.1%), and average time between roll-offs by 16 seconds (25.5%) compared to no convergence. Full convergence resulted in ablation zone volume decrease by 10.3 cm3 (67.7%), time to first roll-off decreased by 5.45 minutes (39.5%), and the average time between roll-offs decreased by 13 seconds (31.4%) compared to no convergence. Preliminary results suggest significant decrease in ablation volume and faster roll-off as the electrode tips increasingly converge. Further experiments are planned to test the study hypothesis with statistical significance. If confirmed, these results suggest confirmation of needle tip geometry prior to ablation should be performed clinically in order to ensure adequate ablation volumes when using Cool-tip Cluster electrodes.Tabled 1Distance Between Electrodes (mm)Diameter of Ablation Zone (cm)Ablation Volume (cm3)Time to First Roll-Off (min)Average Time Between Roll-Offs (sec)44.415.218.535133.49.083.373802.54.913.0835 Open table in a new tab

Needle deflection and tissue sampling length in needle biopsy

This study investigates the effect of needle tip geometry on the needle deflection and tissue sampling length in biopsy. Advances in medical imaging have allowed the identification of suspicious cancerous lesions which then require needle biopsy for tissue sampling and subsequent confirmatory pathological analysis. Precise needle insertion and adequate tissue sampling are essential for accurate cancer diagnosis and individualized treatment decisions. However, the single-bevel needles in current hand-held biopsy devices often deflect significantly during needle insertion, causing variance in the targeted and actual locations of the sampled tissue. This variance can lead to inaccurate sampling and false-negative results. There is also a limited understanding of factors affecting the tissue sampling length which is a critical component of accurate cancer diagnosis. This study compares the needle deflection and tissue sampling length between the existing single-bevel and exploratory multi-bevel needle tip geometries. A coupled Eulerian-Lagrangian finite element analysis was applied to understand the needle-tissue interaction during needle insertion. The needle deflection and tissue sampling length were experimentally studied using tissue-mimicking phantoms and ex-vivo tissue, respectively. This study reveals that the tissue separation location at the needle tip affects both needle deflection and tissue sampling length. By varying the tissue separation location and creating a multi-bevel needle tip geometry, the bending moments induced by the insertion forces can be altered to reduce the needle deflection. However, the tissue separation location also affects the tissue contact inside the needle groove, potentially reducing the tissue sampling length. A multi-bevel needle tip geometry with the tissue separation point below the needle groove face may reduce the needle deflection while maintaining a long tissue sampling length. Results from this study can guide needle tip design to enable the precise needle deployment and adequate tissue sampling for the needle biopsy procedures.

Optimization of sapphire capillary needles for interstitial and percutaneous laser medicine.

.Sapphire capillary needles fabricated by edge-defined film-fed growth (EFG) technique hold strong potential in laser thermotherapy and photodynamic therapy, thanks to the advanced physical properties of sapphire. These needles feature an as-grown optical quality, their length is tens of centimeters, and they contain internal capillary channels, with open or closed ends. They can serve as optically transparent bearing elements with optical fibers introduced into their capillary channels in order to deliver laser radiation to biological tissues for therapeutic and, in some cases, diagnostic purposes. A potential advantage of the EFG-grown sapphire needles is associated with an ability to form the tip of a needle with complex geometry, either as-grown or mechanically treated, aimed at controlling the output radiation pattern. In order to examine a potential of the radiation pattern shaping, we present a set of fabricated sapphire needles with different tips. We studied the radiation patterns formed at the output of these needles using a He–Ne laser as a light source, and used intralipid-based tissue phantoms to proof the concept experimentally and the Monte-Carlo modeling to proof it numerically. The observed results demonstrate a good agreement between the numerical and experimental data and reveal an ability to control within wide limits the direction of tissue exposure to light and the amount of exposed tissue by managing the sapphire needle tip geometry.

Modeling of geometry and insertion force of a new lancet medical needle.

Lancet needle is a typical medical treatment device. Its tip consists of two lancet planes and one bevel plane. When the lancet needle is inserted into soft organ tissue, the insertion force may influence the needle cutting direction and treatment effect and increase the pain. One of the main factors affecting this insertion force is the geometry of the needle tip. Based on the research on the shape and processing method of the conventional lancet needle, a new lancet needle tip geometry was obtained by adjusting the relative position of the grinding wheel to the needle. A mathematical model of this new lancet needle was established. The relationship between processing parameters and needle shape was analyzed, and the needle insertion force was predicted. Compared with the conventional lancet needle, the new lancet needle is sharper, and the insertion force on the cutting edge is smaller. However, this change in the grinding position of the needle lancet plane has a great influence on the shape of needle tip near the intersection of the bevel plane and the lancet plane. Some special second bevel angle and rotated angle will cause a large change in the specific force at the intersection place, which is not conducive to reducing the insertion force.

Five-plane lancet needle design for soft PVC phantom tissue cutting

Lancet needle, having three planes at the tip to generate a sharp lancet point, is the most common needle tip geometry and used for medical procedures. This research presents two five-plane lancet needle designs, the five-plane lancet needle with two back bevels (FLN-B) and five-plane lancet needle with two front bevels (FLN-F), to study the effects of two additional bevel planes on the reduction of soft tissue cutting force. Mathematical models to calculate the inclination angle and rake angle along the cutting edges of FLN-B and FLN-F are developed. By using the grinding process, the prototype FLN-B and FLN-F needles are fabricated. And their inclination and rake angles along the cutting edges are investigated and compared to that of regular lancet needle. Needles insertion tests were conducted on soft PVC phantom which mimics the soft tissue. The initial peak insertion force and steady-state cutting force during needle insertion were identified, and the effect of cutting edge on needle soft tissue cutting force was studied. Compared to lancet needle, FLN-B and FLN-F both have higher inclination and rake angles at the tip cutting edge, could reduce the initial peak needle insertion force and tissue cutting forces, and thus can efficiently cut the soft tissue for medical applications.

Study on design and cutting parameters of rotating needles for core biopsy.

Core needle biopsies are widely adopted medical procedures that consist in the removal of biological tissue to better identify a lesion or an abnormality observed through a physical exam or a radiology scan. These procedures can provide significantly more information than most medical tests and they are usually performed on bone lesions, breast masses, lymph nodes and the prostate. The quality of the samples mainly depends on the forces exerted by the needle during the cutting process. The reduction of these forces is critical to extract high-quality tissue samples. The most critical factors that affect the cutting forces are the geometry of the needle tip and its motion while it is penetrating the tissue. However, optimal needle tip configurations and cutting parameters are not well established for rotating insertions. In this paper, the geometry and cutting forces of hollow needles are investigated. The fundamental goal of this study is to provide a series of guidelines for clinicians and surgeons to properly select the optimal tip geometries and speeds. Analytical models related to the cutting angles of several needle tip designs are presented and compared. Several needle tip geometries were manufactured from a 14-gauge cannula, commonly adopted during breast biopsies. The needles were then tested at different speeds and on different phantom tissues. According to these experimental measurements recommendations were formulated for rotating needle insertions. The findings of this study can be applied and extended to several biopsy procedures in which a cannula is used to extract tissue samples.

A new method for evaluating the normal rake angle and inclination angle on medical needles.

Hollow needles are the most frequently used medical equipment. The design of a hollow needle that best enables medical procedures requires a better understanding of needle tip geometry. Calculating the cutting angles of a needle for a complex surface topology is difficult. This article proposes a new method based on non-Euclidean geometry for the analysis of biopsy needle tip. The method can be used to calculate the cutting angles on any pipe needle. To verify the validity of this method, the normal rake angle and inclination angle on four types of needles (bias bevel needle, cylinder surface needle, curved surface needle and Cournand-type needle) were investigated. It was found that calculation of the cutting angles was simple and convenient using this method, especially for the curved surface needles. Images of the cutting angles from the Cournand-type needles revealed that the smaller bevel angle [Formula: see text] resulted in a higher normal rake angle [Formula: see text] and inclination angle [Formula: see text]. As [Formula: see text] increased, the range of the normal rake angle [Formula: see text] became larger at first and then became smaller.

Mechanics of Tissue Cutting During Needle Insertion in Biological Tissue

In percutaneous needle insertions, cutting forces at the needle tip deflect the needle and increases targeting error. Thus, modeling needle-tissue interaction in biological tissue is essential for accurate robotics-assisted needle steering. In this letter, dynamics of needle tip interaction with inhomogeneous biological tissue is described and the effects of insertion velocity, tissue mechanical characteristics, and needle geometry on tissue cutting force are studied. Needle interaction with biological tissue is divided into three distinct events and modeled. 1) Initial tissue puncturing, which starts by soft tissue deformation and continues until a crack is formed in the tissue. Employing a viscoelastic model of fracture initiation we have predicted the maximum puncturing force and force-displacement response of a needle in contact with a tissue. 2) Tissue cutting, which follows the crack propagation in tissue and is predicted using a novel energy-based fracture model. The model takes account of the needle tip geometry and the tissue mechanical characteristics. 3) Friction between tissue and needle shaft is estimated during needle insertion and retraction using a needle-tissue friction model. Using a needle driving robot ex vivo experiments are performed on a porcine tissue sample to identify the model parameters and validate the analytical predictions offered by the models.

Needle-to-suture ratio, as well as suture material, impacts needle-hole bleeding in vascular anastomoses.

The purpose of this study was to examine the influence of material variables on needle-hole bleeding in vascular anastomoses. Material variables include suture size, needle-tip geometry and diameter, needle coating, suture material and coating and swage area. We attempted to determine whether particular suture material and a reduced needle-to-suture ratio (N:S ratio) could reduce the vessel wall defect and reduce needle-hole bleeding, without changing the suture diameter used for the anastomosis. A comparative analysis was made of the needle-hole leak rate in end-to-end anastomoses of an ePTFE®-ePTFE® vascular graft with a PROLENE® polypropylene suture with HEMO-SEAL™ technology (HS, 1.84:1 N:S ratio), standard PROLENE® polypropylene suture (polypropylene 1, 2.41:1 N:S ratio), an alternate standard PROLENE® polypropylene suture (polypropylene 2, 2.06:1 N:S ratio) and a GORE-TEX™ ePTFE® suture (ePTFE® suture, 1.4:1 N:S ratio) in an ex vivo cardiopulmonary bypass pulsatile flow loop model using heparinized porcine blood. Testing was completed within the model with an activated clotting time between 250 and 500 s, at near normothermia (33-35°C) and at normotensive pressure levels (120/80 mmHg). A sample size of n = 20 was completed for each group. The average total sample leak rate was 19.8 ± 4.5 ml/min for the HS suture, 57.2 ± 7.2 ml/min for polypropylene 1, 33.8 ± 4.1 ml/min for polypropylene 2 and 46.5 ± 10.3 ml/min for the ePTFE suture. The average needle-hole leak rates were 0.63 ± 0.13 ml/min for the HS suture, 1.94 ± 0.23 ml/min for polypropylene 1, 1.14 ± 0.14 ml/min for polypropylene 2 and 1.56 ± 0.34 ml/min for the ePTFE® suture. A two-sided 95% confidence interval for the difference in leak rates showed that there were significant differences (44-67% reduction) in favour of the HS suture when compared with the alternative needles with the same suture material and different N:S ratios, and also a reduction (59%) compared with the sample with smaller N:S ratios but different suture material. The N:S ratio as well as the physical characteristics of the suture material are important factors in reducing needle-hole bleeding in vascular anastomoses.

Modelling of Cutting Force and Deflection of Medical Needles with Different Tip Geometries

Insertion of needle into tissue is influenced by the cutting edges and the needle tip geometry. In this paper, we aimed at investigating the relationship between the insertion forces and cutting edge geometry and general mathematical models of included and inclination angles for two different needle configurations. Two new geometries, one with parabolic cut and other with parabolic surface, cut with two bevel planes have been proposed along with the corresponding mathematical models to improve the cutting edge properties. Results show that parabolic needles after cutting with bevel planes have significantly improved cutting edge properties and are better than the other common needle configurations such as bevel cut. Simulation studies predicted that the deformation and stresses are slightly higher for proposed needle tip geometries than currently available topologies. However, the advantage of included and inclination angles reduce insertion forces thus optimization of medical needle design for the selected tip geometries is a trade-off between insertion forces and deflection in needle.

The Needle With Lancet Point: Geometry for Needle Tip Grinding and Tissue Insertion Force

The grinding procedure and setup, the cutting edge inclination and rake angles of the needle with lancet point (NLP), and the NLP tissue insertion force are investigated in this paper. The NLP is the most commonly used needle tip geometry. However, there is a lack of research on the NLP grinding and cutting edge characteristics. In this study, a four-step grinding procedure and a mathematical model to calculate the inclination and rake angles along the cutting edge of the NLP are developed. Three cases of NLP are defined based on the relative position of the lancets. Prototype NLP for each case was produced and analyzed. Compared to the regular bias bevel needle, grinding two lancets in NLP can increases the inclination angle, particularly at the needle tip. Experiments with needle insertion into the porcine liver were conducted and results showed that NLP could achieve over 40% reduction of the initial peak needle insertion force compared to that of the regular bias bevel needle tip.

Tissue Cutting Mechanics and Applications for Needle Core Biopsy and Guidance

Needle is one of the most common features in medical devices. A better understanding of needle tip geometry can lead to the creation of an optimized needle tip geometry which would greatly benefit the procedure of biopsy or insertion guidance. This study reviews the recent researches on needle cutting edge with high inclination angle, and applications in needle core biopsy and insertion guidance. The mathematical models of the inclination and rake angles for the needle with lancet point and enhanced cutting edge needles are developed. To improve the biopsy length, a novel approach to use the enhanced cutting edge needle to acquire the tissue sample is studied and the concept is experimentally validated. To reduce needle deflection and increase insertion accuracy, the effects of grid constraints, needle material, and insertion speed are analyzed. The knowledge gained from this study can be used to better understand needle tissue cutting mechanics and integrate these technologies for more efficient needle biopsy and accurate insertion guidance procedures.

A Generalized Analytical Model of the Cutting Angles of a Biopsy Needle Tip

A general analytical model of the geometry of a biopsy needle tip is formulated. The model is then used to derive the correlations for the characteristic cutting mechanics angles and for their respective distribution along the active cutting edges of the needle tip. The angles are defined in analogy to the definitions used in cutting tool design for material removal operations. Specifically, analytical expressions for the inclination and rake angles of the tip are derived. The validity of the models was confirmed through their application to plausible needle tip geometries such as: flat, cylindrical and helical tips. The knowledge of the tip geometry and of the relevant angles is a prerequisite for the understanding of tissue cutting mechanics.

Impact of a Modified Needle Tip Geometry on Penetration Force as Well as Acceptability, Preference, and Perceived Pain in Subjects with Diabetes

Multiple factors impact subcutaneous insulin injection pain. Injection devices [e.g., syringe or pen needle (PN)] affect pain due to needle length, diameter, needle polishing and lubrication, and needle tip geometry. We evaluated a modified 5-bevel PN tip in 32 G × 4 mm 31 G × 5 mm and 8 mm PNs vs the equivalent marketed 3-bevel PNs in laboratory penetration force testing, as well as in insulin-taking subjects for overall acceptability, comparative pain, and preference. The clinical tests were done in three ways: paired insertions with the subjects blinded to PN tip geometry, after brief at-home use of 5-bevel PNs, and again with subjects informed about each needle's tip geometry in paired insertions. Average penetration force in a skin substitute was 23% lower with the 5-bevel PNs vs similar 3-bevel PNs (p ≤ 0.01). In blinded testing and after at-home use, patients rated the 5-bevel needle as acceptable. After shortterm home use, patients rated the 5-bevel PN less painful and preferable to their usual PN (both p < 0.01). In paired, informed testing, the 5-bevel PN was less painful and preferred to subjects' currently used needles (p ≤ 0.01) and to other marketed PNs (p < 0.01). Needle tip geometry affects penetration force. When blinded, patients did not distinguish differences in PN tip geometry with fine-gauge PN insertions. A 5-bevel needle tip is perceived as less painful and is preferred by subjects following home use for usual injections. Similar results occurred when patients were informed that they were using a needle with a modified tip.

Modeling cutting edge geometry for plane and curved needle tips

Hollow needles are commonly used in many areas of medicine, yet there has been limited research on needle tip geometry. A better understanding of needle tip geometry can lead to the creation of an optimized needle tip geometry design which would greatly benefit the procedure of biopsy, where a needle is used to cut and remove tissue from the body. The present research develops mathematical models to calculate the inclination and rake angle along the cutting edges of needle tips generated by curved surfaces. The parameters of needle insertion length and inner needle tip surface area are also examined. Needle insertion force is predicted based on needle geometry and calculated for curved and flat plane tip needles. A concave needle produced lower cutting forces than the convex and bias bevel needles. It is found that utilizing curved surface needle tip geometry, as opposed to flat plane geometry, allows for greater control in varying rake and inclination angles on the needle. This greater flexibility allows for more control in designing an optimized needle tip.