scholarly journals Accurate fabrication of aligned nanofibers via a double-nozzle near-field electrospinning

2019 ◽  
Vol 23 (4) ◽  
pp. 2143-2150 ◽  
Author(s):  
Guojie Xu ◽  
Han Wang ◽  
Zhifeng Wang ◽  
Jiarong Zhang ◽  
Rouxi Chen ◽  
...  
Keyword(s):  
Energy Harvester ◽  
Near Field ◽  
Wearable Sensors ◽  
Electrospinning Process ◽  
High Tech ◽  
Direct Write ◽  
Large Area ◽  
Aligned Nanofibers ◽  
Aligned Fibers ◽  
Key Factor

The near-field electrospinning is considered as one of the most effective techniques to direct-write aligned fibers which can be applied to various high-tech areas, including energy harvester, tissue engineering, and wearable sensors. For large area aligned pattern printing, the multi-nozzle electrohydrodynamic print-ing is an efficient method to enhance productivity. As a branch of electrohydro-dynamic printing technology, the near-field electrospinning is a crucial concern to make an investigation for the formation of aligned nanofibers. Here we fabricated various nanostructures from beaded fibers to aligned fibers and crimped fibers by the double-nozzle near-field electrospinning process. We found three key parameters affecting the process, including the collector speed, the applied voltage, and the electrode-to-collector distance, and the collector speed is the key factor affecting the crimped frequency. This paper provides a reliable experi-mental basis and theoretical guidance for the multi-nozzle near-field electrospin-ning to accurately direct-write microfibers and nanofibers.

scholarly journals A new circular spinneret system for electrospinning numerical approach and electric field optimization

2019 ◽  
Vol 23 (4) ◽  
pp. 2229-2235 ◽  
Author(s):  
Ziming Zhu ◽  
Han Wang ◽  
Guojie Xu ◽  
Rouxi Chen ◽  
Lixiong Huang ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Finite Element ◽  
Electric Field ◽  
Large Scale ◽  
Energy Harvester ◽  
Wearable Sensors ◽  
Element Model ◽  
Numerical Approach ◽  
Electrospinning Process ◽  
Effective Technique

Electrospinning is believed to be the most effective technique to produce microfibers or nanofibers at large scale, which can be applied in various hightech areas, including energy harvester, tissue engineering, and wearable sensors. To enhance nanofiber throughput during a multi-needle electrospinning process, it is an effective way to keep the electric field uniform by optimizing electrospinning spinnerets. For this purpose, a novel circular spinneret system is designed and optimized numerically by a 3-D finite element model, the optimal collector shape is also obtained.

scholarly journals Influence and evaluation of array-nozzle geometry on near- field electrospinning direct writing

2019 ◽  
Vol 14 ◽  
pp. 155892501989564
Author(s):  
Jiarong Zhang ◽  
Han Wang ◽  
Zhifeng Wang ◽  
Honghui Yao ◽  
Guojie Xu ◽  
...  
Keyword(s):  
Electric Field ◽  
Near Field ◽  
Microfluidic Channel ◽  
Nozzle Geometry ◽  
Direct Writing ◽  
Large Area ◽  
Linear Arrangement ◽  
Nozzle Length ◽  
Aligned Fibers ◽  
Nozzle Spacing

Near-field electrospinning direct writing of array-nozzle is an efficient method for preparing large-area aligned fibers. However, electric field between the array-nozzle interferes with the stability and uniformity of near-field electrospinning, and little research has been done in this field. To clarify the electric field interference generated by array-nozzle, the experimental results compared with the simulation are discussed. In this work, electric field interference between the five-nozzle linear arrangement near-field electrospinning process was demonstrated by the initial ejection behavior, the electric field distribution of near-field electrospinning environment and the deposition spacing of fibers. In addition, we developed a simple and flexible method serving as a quantitative evaluation index for evaluating the degree of electric field interference. Then, the mapping effects of electric field interference of nozzle structure on the surface morphology and uniformity of aligned fibers were studied, including the number of nozzle, nozzle spacing and nozzle length with linear and toothed arrangement. According to the result of experiment and characterization, suitable arrayed nozzle parameters for stably direct-write aligned array pattern with near-field electrospinning were available, whose geometric parameters are linear two-nozzle with a nozzle spacing of 2 mm and a nozzle length of 6.35 mm. Finally, on the basis of our previous research, a microfluidic channel was successfully prepared on polydimethylsiloxane by two-nozzle cooperation, which verified the rationality of the geometry.

Deposition Characteristics of Direct-Write Suspended Micro/Nano-Structures

2009 ◽  
Vol 60-61 ◽  
pp. 439-444 ◽  
Author(s):  
Gao Feng Zheng ◽  
Ling Yun Wang ◽  
Hong Lian Wang ◽  
Dao Heng Sun ◽  
Wen Wang Li ◽  
...  
Keyword(s):  
Electrostatic Force ◽  
Near Field ◽  
Surface Tension Force ◽  
Solution Concentration ◽  
Water Evaporation ◽  
Direct Write ◽  
Nano Structure ◽  
Electrical Field Strength ◽  
Motion Speed ◽  
Micro Pillars

Direct-Write (DW) technology based on Near-Field Electrospinning (NFES) was introduced to fabricate suspended micro/nano-structure on pattern substrate, and the deposition behaviors of DWed structure under different collector motion speed (CMS) were discussed to improve control of DW technology based on NFES. Deposit point of DWed structure on the substrate can be controlled accurately under the observation of microscope, and position error of micro/nano-structure is less than 5µm. When CMS is compatible with the electrospinning speed, straight line micro/nano-structure can be direct-written across micro-trenches with width of 5~40µm or to bridge two micro-pillars with diameter of 10µm. Due to the water evaporation and surface tension force, DWed structures suspended in the air would shrink smaller compared with that deposited on the top surface of pattern. The shrink ratio of micro-structure is higher than nano-structure and the shrink ratio decreases with the solution concentration increases. When the CMS is lower than electrospinning speed, the electrostatic force and elastic force would play a more prominent role on the deposition behavior of DWed structure. The electrical field strength on the top surface of pattern is higher than the space between two patterns, DWed thin film would deposit along the trip pattern and nanofiber would prefer to aggregate on the top surface of pattern under electrostatic force. When solution concentration is lower than 18%, nanofiber aggregate on the pattern would coagulate to form polymer bundle.

scholarly journals A Survey of NFC Sensors Based on Energy Harvesting for IoT Applications

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3746 ◽  
Author(s):  
Antonio Lazaro ◽  
Ramon Villarino ◽  
David Girbau
Keyword(s):  
Energy Harvesting ◽  
Integrated Circuits ◽  
Radio Frequency Identification ◽  
Low Cost ◽  
Near Field ◽  
Wearable Sensors ◽  
Cold Chain ◽  
Iot Applications ◽  
Wide Range ◽  
Frequency Identification

In this article, an overview of recent advances in the field of battery-less near-field communication (NFC) sensors is provided, along with a brief comparison of other short-range radio-frequency identification (RFID) technologies. After reviewing power transfer using NFC, recommendations are made for the practical design of NFC-based tags and NFC readers. A list of commercial NFC integrated circuits with energy-harvesting capabilities is also provided. Finally, a survey of the state of the art in NFC-based sensors is presented, which demonstrates that a wide range of sensors (both chemical and physical) can be used with this technology. Particular interest arose in wearable sensors and cold-chain traceability applications. The availability of low-cost devices and the incorporation of NFC readers into most current mobile phones make NFC technology key to the development of green Internet of Things (IoT) applications.

scholarly journals Shape-Controlled, Single-Crystal Gold Surface Nanostructures

2019 ◽  
Author(s):  
Sasan V. Grayli ◽  
Xin Zhang ◽  
Dmitry Star ◽  
Gary Leach
Keyword(s):  
Single Crystal ◽  
Electroless Deposition ◽  
Near Field ◽  
Critical Role ◽  
Deposition Process ◽  
Local Fields ◽  
Metal Nanostructures ◽  
Large Area ◽  
Device Applications ◽  
Shape Controlled

Size, shape and crystallinity play a critical role in the wavelength-dependent optical responses and plasmonic local near-field distributions of metallic nanostructures. While their enhanced local fields can drive new and useful chemical and physical processes, the ability to fabricate shape-controlled single-crystal metal nanostructures and position them precisely on substrates for device applications represents a significant barrier to harnessing their greater potential. Here, we describe a novel electroless deposition process in the presence of anionic additives that yields additive-specific, shape-controlled, single-crystal plasmonic Au nanostructures on Ag(100) and Au(100) substrates. Deposition of Au in the presence of SO<sub>4</sub><sup>2-</sup> ions results in the formation of smooth Au(111)-faceted square pyramids that show large surface enhanced Raman responses. The use of halide additives such as Cl<sup>-</sup> and Br<sup>- </sup>that interact strongly with (100) facets produces highly textured hillock-type structures characterized by edge and screw-type dislocations (Cl<sup>-</sup>), or flat platelet-like features characterized by large area Au(100) terraces with (110) step edges (Br<sup>-</sup>). Use of additive combinations provides structures that comprise characteristics derived from each additive including new square pyramidal structures with dominant Au(110) facets (SO<sub>4</sub><sup>2-</sup>and Br<sup>-</sup>). Finally we demonstrate that this bottom-up electroless deposition process, when combined with top-down lithographic patterning methods, can be used to position shape-controlled, single-crystal Au nanostructures with precise location and orientation on surfaces. We anticipate that this approach will be employed as a powerful new tool to tune the plasmonic characteristics of nanostructures and facilitate their broader integration into device applications.

scholarly journals Processing variables of direct-write, near-field electrospinning impact size and morphology of gelatin fibers

2020 ◽  
Author(s):  
Zachary G. Davis ◽  
Aasim F. Hussain ◽  
Matthew B. Fisher
Keyword(s):  
Acetic Acid ◽  
Acid Concentration ◽  
Near Field ◽  
Fiber Formation ◽  
Direct Write ◽  
Acetic Acid Concentration ◽  
Direct Writing ◽  
Fiber Morphology ◽  
Gelatin Concentration ◽  
The Impact

AbstractSeveral biofabrication methods are being investigated to produce scaffolds that can replicate the structure of the extracellular matrix. Direct-write, near-field electrospinning of polymer solutions and melts is one such method which combines fine fiber formation with computer-guided control. Research with such systems has focused primarily on synthetic polymers. To better understand the behavior of biopolymers used for direct-writing, this project investigated changes in fiber morphology, size, and variability caused by varying gelatin and acetic acid concentration, as well as, process parameters such as needle gauge and height, stage speed, and interfiber spacing. Increasing gelatin concentration at a constant acetic acid concentration improved fiber morphology from large, planar structures to small, linear fibers with a median of 2.3 µm. Further varying the acetic acid concentration at a constant gelatin concentration did not alter fiber morphology and diameter throughout the range tested. Varying needle gauge and height further improved the median fiber diameter to below 2 µm and variability of the first and third quartiles to within +/-1 µm of the median for the optimal solution combination of gelatin and acetic acid concentrations. Additional adjustment of stage speed did not impact the fiber morphology or diameter. Repeatable interfiber spacings down to 250 µm were shown to be capable with the system. In summary, this study illustrates the optimization of processing parameters for direct-writing of gelatin to produce fibers on the scale of collagen fibers. This system is thus capable of replicating the fibrous structure of musculoskeletal tissues with biologically relevant materials which will provide a durable platform for the analysis of single cell-fiber interactions to help better understand the impact scaffold materials and dimensions have on cell behavior.

Numerical Simulation of Viscous Jet for Near-Field Electrospinning

2009 ◽  
Vol 60-61 ◽  
pp. 465-469 ◽  
Author(s):  
Yuan Yuan Zhong ◽  
Gao Feng Zheng ◽  
Dao Heng Sun
Keyword(s):  
Numerical Simulation ◽  
Field Strength ◽  
Process Parameters ◽  
Near Field ◽  
Solution Concentration ◽  
Electrospinning Process ◽  
Substrate Distance ◽  
Viscous Jet ◽  
Set Up ◽  
The Impact

Near-Field Electrospinning (NFES) is a newly developed method to fabricate continuous and ordered solid nanofibers, with smaller spinneret-to-collector-distance the behavior of viscous jet would play a more prominent effect on the deposition and morphology of nanofiber. In this paper, a 2-dimentional physical model based on electrohydrodynamics and rheology was set up to discuss the morphology of viscous jet for NFES. The profile of the jet along z direction can be predicted by this model, and the impact of process parameters on the jet radius is analyzed. Radius of jet decreases with spinneret-to-substrate-distance decreasing; jet radius decreases with applied voltage and electric field strength increasing; jet electrospun from PEO solution is thinner than that from PVA solution with the same solution concentration; solution concentration has insignificant influence on the radius of jet from solution of the same polymer (PVA or PEO). This numerical simulation would improve the control of electrospinning process in NFES.

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