Needle Structure Research Articles

An Intriguing Interpretation of 1D and 2D Non-Diffracting Modes in Cosine Profile

We provide a simple analysis based on ray optics and Dirac notation for 1D (one-dimensional) and 2D (two-dimensional) non-diffracting modes in the cosine profile, which are often called Cosine beams. We explore various kinds of structured modes formed by the superposition of two 1D Cosine beams. We then went on to understand the properties of the Bessel beams in terms of Cosine beams. For the first time, we report on the generation of three-dimensional tunable needle structures based on the interference of 1D Cosine beams. These size-tunable optical needles can have multiple advantages in material processing. Also, we report, for the first time, on the Talbot effect in Cosine beams. Straightforward mathematical calculations are used to derive analytical expressions for Cosine beams. The present method of demonstrating Cosine beams may be utilized to understand other structured modes. The Dirac notation-based interference explanation used here can provide new researchers with an easy way to understand the wave nature of light in a fundamental aspect of interferometric experiments as well as in advanced-level experiments such as beam engineering technology, imaging, particle manipulation, light sheet microscopy, and light–matter interaction. We also provide an in-depth analysis of similarities among Cosine, Bessel, and Hermite–Gaussian beams.

Features of the anatomical structure of <i>Juniperus foetidissima</i> Willd. needles in the conditions of the Crimean Peninsula

Currently, the natural flora of Crimea includes 5 species of junipers, the smallest of which is J. foetidissima. The anatomical structure of needles is an important diagnostic feature that allows one to assess the intraspecific variability of rare species and the stability of their tree stands. In the conditions of the Crimean Mountains, extensive intercellular spaces are clearly visualized on a cross section of J. foetidissima needles. Such a feature of the anatomical structure of the needles of the species under study has not been described previously. The proportion of intercellular spaces varies from 5,36% to 20,89%, on average, their area is 0,018 ± 0,002 mm². Intercellular spaces are located in the central part of the needles between the vascular bundle and the resin canal, and sometimes on both sides of it. The mesophyll is very loose here. Along the periphery, the dense mesophyll consists of 3–5 rows of elongated oval cells. In addition, there is one fairly large resin channel. Its area can occupy up to 15% of the total cross-sectional area of the needles. The correlation dependences of the parameters of the anatomical structure of the needles of J. foetidissima are similar to those of J. deltoides, which, in turn, has a needle-shaped needle type. The drought resistance coefficient of the studied species made it possible to classify them as mesophytes.

Siberian Fir Needles Growth and Structural Features Studied in the North-East of the European Russia

Siberian fir (Abies sibirica Ledeb.) is the subject of this research and is the least studied forest-forming species in the North-East of the European Russia. The purpose of the work is to study changes in the structure of fir needles in the process of its growth. The paper is based on a growth model and examines the relationship between the linear dimensions of Siberian fir needles and changes in the anatomical structure and ultrastructure of its assimilation apparatus during the period of its growth outside the bud. A logistic model was successfully tested as a model of changes in fir needles’ linear dimensions (length, width and thickness), and proved to be a convenient tool for analysing the processes of needle development at all structural levels. The application of the model makes it possible to identify the phases of needle development and confirm the synchronism in changes in the linear dimensions of needles with the development of assimilation cells. It has been shown that when the needles of Siberian fir emerge from the bud, they are already qualitatively capable of photosynthesis, as evidenced by the presence of developed thylakoids and grana in chloroplasts, as well as photosynthetic pigments. The assimilation apparatus reaches its highest qualitative and quantitative development after the end of the last phase of needle growth in length, which gives us grounds to conclude that under optimal environmental conditions, already developed needles reach the highest functional activity during this period.

Visual servoing-based pneumatic hair transplantation mechanism for robotic FUE surgery

Hair transplantation surgery is an effective solution for hair loss problems, among which follicle unit extraction (FUE) surgery is more widely used and favored. At present, most hair transplantation surgeries still rely heavily on manual operation by doctors and very few hair transplantation robots with complex structures have been introduced. This paper proposes a pneumatic hair transplantation mechanism for FUE surgery, equipped with a camera, capable of automatically performing both hair implantation and extraction with airflow. This pneumatic method eliminates the complex needle structure, has the function of temporarily storing the follicles inside the needle, thus facilitating the automation of transferring follicles from extraction to implantation. Then a visual feedback system is proposed to accurately position the follicles during the transplantation. The experimental results show that average distance deviation between the actual and target positions is 0.6128 mm and the average deviation of hair implantation depth is 1.7176 mm, which verify the feasibility of the proposed system.

Model-Based Needle Identification Using Image Analysis and Needle Library Matching for Ultrasound-Guided Kidney Biopsy: A Feasibility Study.

The aim of the work described here was to determine the feasibility of using a novel biopsy needle detection technique that achieves high sensitivity and specificity in a trade-off of resolution, detectability and depth of imaging. The proposed needle detection method consists of a model-based image analysis, temporal needle projection and needle library matching: (i) Image analysis was formulated under the signal decomposition framework; (ii) temporal projection converted the time-resolved needle dynamics into a single image of the desired needle; and (iii) the enhanced needle structure was spatially refined by matching a long, straight linear object in the needle library. The efficacy was examined with respect to different needle visibility. Our method effectively eliminated confounding effects of the background tissue artifacts more robustly than conventional methods, thus improving needle visibility even with the low contrast between the needle and tissue. The improvement in needle structure further resulted in an improvement in estimation performance for the trajectory angle and tip position. Our three-step needle detection method can reliably detect needle position without the need for external devices, increasing the needle conspicuity and reducing motion sensitivity.

Bioadhesive microneedle patches for tissue sealing

AbstractSealing of soft tissues prevents leakage of gas and liquid, closes wounds, and promotes healing and is, therefore, of great significance in the clinical and medical fields. Although various formulations have been developed for reliable sealing of soft tissue, tradeoffs between adhesive properties, degradation profile, and tissue toxicity limit their clinical use. Hydrogel‐based adhesives, for example, are highly biocompatible but adhere very weakly to the tissue and degrade quickly, while oxidized cellulose patches are poorly absorbed and may cause healing complications postoperatively. Here, we present a novel strategy for tissue sealing based on bioadhesive microneedle patches that can spontaneously adhere to tissue surface through electrostatic interactions and swell within it. A series of microneedle patches made of pullulan, chitosan, Carbopol, poly (lactic‐co‐glycolic acid), and a Carbopol/chitosan combination were fabricated and characterized for their use in tissue sealing. The effect of microneedle composition on the fabrication process, physical and mechanical properties, in vitro cytotoxicity, and in vivo biocompatibility were examined. The needle structure enables microneedles to strongly fix onto various tissues via physical interlocking, while their adhesive properties improve staying time and sealing capabilities. The microneedle patch comprising Carbopol needles and chitosan as a second pedestal layer presented the best results in terms of sealing and adhesion, a consequence of the needle's swelling and adhesion features combined with the supportive chitosan base layer. Finally, single Carbopol/chitosan patches stopped intense liver bleeding in a rat model significantly quicker and with less blood loss compared with commercial oxidized cellulose patches. These microneedles can be considered a promising cost‐effective platform for adhering and sealing tissues as they can be applied quickly and painlessly, and require less trained medical staff and equipment.

Towards a Procedure-Optimised Steerable Catheter for Deep-Seated Neurosurgery.

In recent years, steerable needles have attracted significant interest in relation to minimally invasive surgery (MIS). Specifically, the flexible, programmable bevel-tip needle (PBN) concept was successfully demonstrated in vivo in an evaluation of the feasibility of convection-enhanced delivery (CED) for chemotherapeutics within the ovine model with a 2.5 mm PBN prototype. However, further size reductions are necessary for other diagnostic and therapeutic procedures and drug delivery operations involving deep-seated tissue structures. Since PBNs have a complex cross-section geometry, standard production methods, such as extrusion, fail, as the outer diameter is reduced further. This paper presents our first attempt to demonstrate a new manufacturing method for PBNs that employs thermal drawing technology. Experimental characterisation tests were performed for the 2.5 mm PBN and the new 1.3 mm thermally drawn (TD) PBN prototype described here. The results show that thermal drawing presents a significant advantage in miniaturising complex needle structures. However, the steering behaviour was affected due to the choice of material in this first attempt, a limitation which will be addressed in future work.

One-piece knitted embedded hang-needle sensor for shoulder posture recognition

Wearable products have significant applications in medical assistance, posture correction, and humancomputer interaction. In this study, we present a knitting method for a one-piece knitted embedded hang-needle sensor. This method involves simultaneously knitting conductive yarn into the sensing zone while creating the monitoring garment in a seamless manner. By implementing a tight hanging needle structure in the sensing zone design and adjusting knitting parameters, the effect of pre-stretching on the sensor caused by the base garment is minimized. Furthermore, integrating the sensing area of the hang-needle structure with the monitoring garment eliminates the need for additional sensor integration steps and simplifies the preparation process, resulting in reduced time and material costs. Moreover, the monitoring garment offers a comfortable wearing experience without any foreign body sensation and accurately captures the initial shoulder posture of the wearer.

Hollow silicon microneedles, fabricated using combined wet and dry etching techniques, for transdermal delivery and diagnostics

Microneedle-based technologies are the subject of intense research and commercial interest for applications in transdermal delivery and diagnostics, primarily because of their minimally invasive and painless nature, which in turn could lead to increased patient compliance and self-administration. In this paper, a process for the fabrication of arrays of hollow silicon microneedles is described. This method uses just two bulk silicon etches – a front-side wet etch to define the 500 μm tall octagonal needle structure itself, and a rear-side dry etch to create a 50 μm diameter bore through the needle. This reduces the number of etches and process complexity over the approaches described elsewhere. Ex-vivo human skin and a customised applicator were used to demonstrate biomechanical reliability and the feasibility of using these microneedles for both transdermal delivery and diagnostics. Microneedle arrays show no damage even when applied to skin up to 40 times, are capable of delivering several mL of fluid at flowrates of 30 μL/min, and of withdrawing 1 μL of interstitial fluid using capillary action.

Alpha-MnO2 nanoneedle embedded in MgO-chitosan biochar for higher removal of arsenic from groundwater: Co-effects of oxidation and adsorption

High performance and high permeability of reactive materials are crucial issues for the remedy of arsenic (As)-enriched groundwater by permeable reactive barriers. The remediation strategy integrating adsorption and oxidation has gained wide concerns due to its deep removal for As(Ⅲ). In this study, a granular bifunctional nanocomposite MgO-Chitosan-MnO2 (MgO-CS-MnO2) was fabricated as permeable reactive media for the in-situ remediation for high As groundwater. The needle structure of MnO2 could provide adequate oxidation sites, furthermore, the multilayer porous characteristic of MgO-CS could also meet higher adsorption capacity. As a result, the estimated maximal adsorption capacity of MgO-CS-MnO2 for As(Ⅲ) reached to 266.61 mg/g and 578.05 mg/g for arsenate (As(Ⅴ)), which are much higher than current similar adsorbents. The adsorption behaviors of As(Ⅲ/Ⅴ) follow pseudo-second-order kinetic model and Freundlich isotherm model, suggesting that both As(Ⅲ) and As(Ⅴ) are mainly chemisorbed onto MgO-CS-MnO2. It could perform effectively in a broad range of pH values (3−11), moreover, competing oxyanions (CO32-, NO-, and SO42-), organic matters (humic acid) and ion strength exert no significant influence towards As remediation. XPS results revealed As(Ⅲ) adsorbed onto composite completely transformed to As(Ⅴ), and removal mechanisms involved oxidation and metal-O-As(Ⅲ/Ⅴ) complexation. In addition, it can be easily regenerated and recycled maintaining an excellent adsorption and oxidative ability. Besides, Column experiment demonstrated this composite column could effectively treat 1300 and 1700 bed volume (BV) of synthetic As(Ⅲ/Ⅴ)-contaminated groundwater, respectively. Therefore, MgO-CS-MnO2 have a great potential applicability towards high As groundwater improvement as permeable reactive media.

Influence of Mechanical Properties on the Piezoelectric Response of UV-Cured Composite Films Containing Different ZnO Morphologies

ZnO flower-like (ZFL) and needle (ZLN) structures were synthesized and embedded into UV-curable acrylic resin (EB), with the aim to study the effect of filler loading on the piezoelectric properties of the resulting composite films. The composites showed uniform dispersion of fillers within the polymer matrix. However, by increasing the filler amount, the number of aggregates increased, and ZnO fillers appeared not to be perfectly embedded in polymer film, indicating poor interaction with acrylic resin. The filler content increase caused an increase in glass transition temperature (Tg) and a decrease in storage modulus in the glassy state. In particular, compared with pure UV-cured EB (Tg = 50 °C), 10 wt.% ZFL and ZLN presented Tg values of 68 and 77 °C, respectively. The piezoelectric response generated by the polymer composites was good when measured at 19 Hz as a function of the acceleration; the RMS output voltages achieved at 5 g were 4.94 and 1.85 mV for the composite films containing ZFL and ZLN, respectively, at their maximum loading levels (i.e., 20 wt.%). Further, the RMS output voltage increase was not proportional to the filler loading; this finding was attributable to the decrease in the storage modulus of the composites at high ZnO loading rather than the dispersion of filler or the number of particles on the surface.

Laser-synthesised magnesium nanoparticles for amino acid and enzyme immobilisation

Enzyme and amino acid immobilisation increase the efficiency of biochemical reactions while facilitating a mechanism for their delivery to tissues. Herein, clean MgNPs were fabricated via laser ablation and were mixed and ultrasonicated together with trypsin and glutamine for immobilisation. The as-synthesised MgNPs of various concentrations exhibited human dermal fibroblast cell growth-promoting effects and an improved dynamic reciprocity environment as demonstrated via cell adhesion. Adsorption was the mechanism used for immobilising amino acids and enzymes onto MgNPs. The resulting composites, visualised via FESEM, appeared as highly connected needle structures. Immersion in DI water was employed for chemical elution while centrifugation at 12,000 rpm and filtration through 200 nm pore sizes were applied to induce physical elution. The microstructure of the MgNPs-trypsin composites did not change significantly after elution while the MgNPs-trypsin composites showed morphological changes from a monolithic structure to a disaggregated structure.

In situ microscopy of composite Germanium/Germanium oxide microneedle growth

Composite germanium/germanium oxide needles with a carcass/filler structure, thicknesses of 0.25–10 µm and lengths up to 450 µm were grown by chemical transport involving gaseous GeO. The synthesis was carried out at temperatures of 897–1100 K in a newly developed miniature cell. Through a top window one can observe the growth process in situ via video microscopy. The cell can be evacuated and sealed, enclosing all products generated in reactions, but can easily be opened afterwards for an ex situ analysis of the needles. The in situ observations show that the needles grow with longitudinal velocities of up to 30 µm/s, depending on temperature and needle thickness, and with lateral velocities of up to 0.11 µm/s. The surface structure and the cross-sections of the needles were studied ex situ by SEM as well as EDX spectroscopy combined with element mapping. The surface structure of needles exhibits highly regular arrays of germanium/germanium oxide microunits but also shows irregularities and defects. The study of the longitudinal section and the lamella showed that this regularity is remarkable also inside the needle all way down to the core. Furthermore, according to the SAED and Raman spectroscopy, the needle carcass (core with branches) is mainly composed of a cubic Ge and an amorphous filling mass of Ge and O, which presumably corresponds to GeO2.

Toward Efficient Wound Management: Bioinspired Microfluidic and Microneedle Patch.

Microneedle (MN) patches hold demonstrated prospects in intelligent wound management. Herein, inspired by the highly folded structure of insect wings, a three-dimensional (3D) origami MN patch with superfine miniature needle structures, microfluidic channels, and multiple functions wasreported to detect biomarkers, release drugs controllably and monitor motions to facilitate wound healing. By simply replicating the pre-stretched silicone rubber (Ecoflex) molds patterned by a laser engraving machine, the superfine structure MN patch with microfluidic channels wasobtained from the restored molds. The bioinspired origami structure endows the MN patch with a high degree of functional integration, including microfluidic channels and electrocircuits. The microfluidic channels combined with the pH value and glucose concentration indicators enable the patch with the capability of biomarker sensing detection. Porous structures, a temperature-responsive hydrogel, and a photothermal-sensitive agent are utilized to form a controllable drug release system on the MN patch. Meanwhile, MXene electrocircuits wereprinted on the MN patch for motion sensing. In addition, the ability of the MN patch to accelerate wound healing wasdemonstrated by a mouse model experiment with full-thickness skin wounds. These results indicate that the multifunctional 3D origami MN patch is a valuable intelligent strategy for wound management.

Study on the Vibration Characteristics of the Spraying Needle Excited by Electro-hydraulic Source Based on Luminous Energy Method

When one kind of liquid was atomized by a metal needle in the electric field, violent vibration of the spraying needle could be observed clearly, and the atomizing stability was affected by it seriously. To explore the cause of the needle’s vibration and weaken its negative effect, an optical energy method was adopted and some characteristics of the vibration were investigated. The principle of the optical energy method was very simple, it was just a transformation from mechanical information of the needle’s vibration to an optical signal composed with luminous energy features and received by a photodiode. The prototype of it was composed by a luminous source system and a testing circuit cored with MCU STC89C52. After the electronic signal transferred from the luminous energy was analysed, some characteristics come from different needles under different working conditions can be obtained. Some results are: the cause of the vibration comes from dual incentives of the electrostatic field and the atomized liquid jet, in view of mechanical structure, the length and diameter of the spraying needle was the main factors affecting the vibration amplitude and frequency, considering the flow rate flow through the spraying needle, there are different starting vibration voltages for different flow rate at the same length and diameter.

Room temperature single-photon emission from InGaN quantum dot ordered arrays in GaN nanoneedles

GaN-based single-photon sources have received immense attention for applications in quantum technologies. An isolated semiconductor quantum dot (QD) is an attractive and proven choice. Most experimental demonstrations involve epitaxial growth or etching of the QD embedded in a vertical nanopillar/nanowire structure. Here, we demonstrate room-temperature single-photon emission from an InGaN QD embedded in a GaN nanoneedle. The nanoneedle is tapered at the bottom and is formed by a succession of inductively coupled plasma reactive ion etching and crystallographic direction-dependent wet etching techniques. The nanofabrication process steps yield reproducible and uniform-sized QDs in the needle structures. Cross-sectional SEM images show needles are centered at the center of a hexagonal base, which confirms a good crystalline property of the QD. Micro-photoluminescence measurements on a single QD manifest a short time constant for radiative decay channels without any prominent non-radiative decay path. Second-order correlation measurements confirm the antibunching of the emitted photons. Higher spectral purity and smaller value of the second-order correlation are maintained up to a good excitation power, indicating the usefulness of the methodology for quantum technologies.

CuO nanomesh hierarchical structure for directional water droplet transport and efficient fog collection

Collecting water from fog is a promising approach to solve the shortage of water resources by micro-nano scale hierarchical structure material surface. Inspired by the structures of cactus and pine needles, CuO micro-nano scale structures attached to the surface of Cu foam are designed to increase the efficiency of fog collection and droplet transport. The structural evolution from CuO nanowires to CuO nanomesh and CuO nanosheets is achieved by regulating the synthesis conditions. The results show that the synthesized CuO nanomesh hierarchical structure is more favorable for fog collection, and the collection efficiency can achieve a rate of up to 34.6 mg/cm2 s. The tip structure can rapidly capture and coalesce small droplets in a foggy environment, which significantly improves the fog collection efficiency. In addition, the synthesized mesh structure and inter-neighborhood gaps have a strong ability to confine air, making the surface has small adhesion and enabling water droplets to fall quickly, which realizes the transport of the collected water efficiently and sustainably. The research work opens a new path for constructing surface structures to improve fog collection performance and has reference value and promotion for the design and development of fog collectors.

Material design and temperature field simulation analysis of tumor radiofrequency ablation needle

To solve the problems of small one-time ablation range and easy charring of the tissue around the electrode associated with the tumor radiofrequency ablation needle, based on the multiphysical field coupling analysis software COMSOL, the effects of needle material, the number of sub needles and the bending angle of sub needles on the ablation effect of radiofrequency ablation electrode needle were studied. The results show that compared with titanium alloy and stainless steel, nickel titanium alloy has better radiofrequency energy transmission efficiency and it is the best material for electrode needle. The number of sub needles has a great influence on the average necrosis depth and the maximum necrosis diameter. Under the same conditions, the more the number of sub needles, the larger the volume of coagulation necrosis area. The bending angle of the needle has a great effect on the maximum diameter of the coagulated necrotic area, but has little effect on the average necrotic depth. Under the same other conditions, the coagulation necrosis area formed by ablation increased with the increase of the bending angle of the sub needle. For the three needles with bending angles of 60 °, 90 ° and 120 ° analyzed in this paper, the one with bending angle of 120 ° can obtain the largest coagulation necrosis area. In general, the design of nickel titanium alloy with 120 ° bending 8-pin is the optimal. The average depth of radiofrequency ablation necrosis area is 32.40 mm, and the maximum necrosis diameter is 52.65 mm. The above optimized design parameters can provide guidance for the structure and material design of tumor radiofrequency ablation needle.

Clean iron removal from zinc leaching solution by shear enhancement: Industrial pilot campaign and strengthening mechanism

A clean goethite process for iron removal was proposed to overcome the challenges of large amount of hazardous iron waste and low reaction rate. First, the forms of substances in zinc leaching solution and iron precipitation residue were analyzed by thermodynamic calculation. The process parameters were then optimized by industrial test, and the strengthening mechanism was revealed by numerical simulation. Finally, the industrial application of the process was evaluated. Results indicated that the stable phase of goethite existed in the pH range of 2.8–4.2 at 80 °C. The concentration of iron was reduced from 11.94 g L−1 to 2.08 g L−1 at 6 h under optimal conditions, and the iron and zinc contents in the residue with needle structure were 49.95 wt% and 6.02 wt%, respectively. The shear-enhanced process accelerated the flow rate and improved the gas dispersion, leading to the rapid homogenization of solution and increased reaction rate. In addition, the oxygen utilization rate of the shear-enhanced goethite process was 39.33% higher than that of the traditional process. The shear-enhanced process achieved a 20% reduction in waste residue, and the production cost was 0.85 $ kg−1.

TiC strengthened CoCrNi medium entropy alloy: Dissolution and precipitation of TiC and its effect on microstructure and performance

In order to improve the strength and corrosion resistance of CoCrNi medium entropy alloy, TiC strengthened CoCrNi medium entropy alloy (CoCrNi/(TiC)x (x=0.1, 0.2, 0.4)) was designed by addition of different amounts of TiC. The effects of TiC content on the microstructure, mechanical properties, and corrosion resistance of the alloy were investigated. It was found that the precipitation morphologies of TiC changed from lamellar eutectic to needle structure with the increase of TiC content, and finally formed mixed needled and bulk TiC particles. TiC appears as a dissolution−precipitation phenomenon in the CoCrNi alloy, which is important for the mechanical properties and corrosion resistance of the CoCrNi/(TiC)x alloy. The strength of alloy was enhanced obviously after the addition of TiC. The compressive yield strength of CoCrNi/(TiC)0.4 alloy reached 746 MPa, much larger than that of the CoCrNi medium entropy alloy, 108 MPa. Additionally, the addition of TiC was found to improve the corrosion resistance of CoCrNi medium entropy alloy in the salt solution.