High-speed Spinning Research Articles

High-speed spinning disks on flexible threads

A common spinning toy, called “buzzer”, consists of a perforated disk and flexible threads. Despite of its simple construction, a buzzer can effectively transfer translational motions into high-speed rotations. In the present work, we find that the disk can be spun by hand at an extremely high rotational speed, e.g., 200,000 rpm, which is much faster than the previously reported speed of any manually operated device. We explore, both experimentally and theoretically, the detailed mechanics and potential applications of such a thread–disk system. The theoretical prediction, validated by experimental measurements, can help design and optimize the system for, e.g., easier operation and faster rotation. Furthermore, we investigate the synchronized motion of multiple disks spinning on a string. Distinctly different twist waves can be realized by the multi-disk system, which could be exploited in the control of mechanical waves. Finally, we develop two types of manually-powered electric generators based on the thread–disk system. The high-speed rotation of the rotors enables a pulsed high current, which holds great promise for potential applications in, for instance, generating electricity and harvesting energy from ocean waves and other rhythmic translational motions.

Differentiation of molecular chain entanglement structure through laser Raman spectrum measurement of High strength PET fibers under stress

The aim of this study was to investigate the mechanism for the improvement of mechanical properties of poly(ethylene terephthalate) (PET) fibers based on the concept of controlling the state of molecular entanglement. For this purpose, five different PET fibers were prepared through either the conventional melt spinning and drawing/annealing process or the high-speed melt spinning process. In both cases, the melt spinning process was designed so as to realize different Deborah number conditions. The prepared fibers were subjected to the laser Raman spectroscopy measurement and the characteristics of the scattering peak at around 1616 cm−1, which corresponds to the C-C/C=C stretching mode of the aromatic ring in the main chain, were investigated in detail. It was revealed that the fibers drawn and annealed after the melt spinning process of lower Deborah number showed higher tensile strength as well as lower value of full width at half maximum (FWHM) in the laser Raman spectrum. Narrow FWHM was considered to represent the homogeneous state of entanglement structure, which may lead to the higher strength and toughness of fibers because individual molecular chains tend to bare similar level of tensile stress when the fiber is stretched. In case of high-speed spun fibers prepared with a high Deborah number condition, the FWHM was narrow presumably because much lower tensile stress in comparison with the drawing/annealing process was applied when the fiber structure was developed, however the value increased significantly upon applying tensile load to the fibers during the laser Raman spectrum measurement. From these results, it was concluded that the Laser Raman spectroscopy could differentiate molecular chain entanglement structure of various fiber samples, in that low FWHM, which corresponds to either homogeneous state of molecular entanglement or lower level of mean residual stress, and small increase of FWTH upon applying tensile stress are considered to be the key factors for the improvement of the mechanical properties of PET fibers.

Controlling Mechanism of Molecular Orientation of Poly(3-alkylthiophene) in a Thin Film Revealed by Using pMAIRS

A face-on oriented thin film of poly(3-hexylthiophene) (P3HT) is suitable for an organic semiconductor layer in a photovoltaic device, and thus analysis of the film structure in terms of molecular orientation is crucial. Although the face-on film often has a poor crystallinity, diffraction techniques have long been employed for the structural analysis, and only very minor crystal parts have been discussed. In our previous study, P3HT was revealed to have a uniquely oriented structure even in an amorphous film by using p-polarized multiple-angle incidence resolution spectrometry (pMAIRS), which is powerful to analyze the molecular orientation, crystallinity, and the conjugation length of P3HT. With the best use of the potential of pMAIRS, in the present study, the controlling mechanism of the molecular orientation of P3HT correlated with the crystallinity in a spin-coated thin film is revealed. As a result, by employing a high-spin speed at 8000 rpm, a highly face-on oriented thin film having a very low cr...

Prospective lines of development of polyester fiber and yarn manufacturing technology

The process of poly(ethylene terephthalate) (PET) structure formation in the course of drawing and high-speed spinning, which forms the basis for the development of polyester fiber and yarn manufacturing technology, is considered. The possibility of a change in the structural mechanical properties of PET yarns is demonstrated. Perspective lines of development of polyester fiber and yarn manufacturing technology, including nanotechnology, are considered.

Model Based Motion State Estimation and Trajectory Prediction of Spinning Ball for Ping-Pong Robots using Expectation-Maximization Algorithm

Motion state "Motion state of a ping-pong ball consists of the flying state and spin state." estimation and trajectory prediction of a spinning ball are two important but challenging issues for both the promotion of the next generation of robotic table tennis systems and the research on motion analysis of spinning-flying objects. Due to the Magnus force acting on the ball, the flying state "Flying state denotes the real-time translational velocity." and spin state "Spin state denotes the real-time rotational velocity." are coupled, which makes the accurate estimation of them a huge challenge. In this paper, we first derive the Extended Continuous Motion Model (ECMM) by clustering the trajectories into multiple categories with a K-means algorithm and fitting them respectively using Fourier series. The ECMM can easily adapt to all kinds of trajectories. Based on the ECMM, we propose a novel motion state estimation method using Expectation-Maximization (EM) algorithm, which in result contributes to an accurate trajectory prediction. In this method, the category in ECMM is treated as a latent variable, and the likelihood of motion state is formulated as a Gaussian Mixture Model (GMM) of the differences between the trajectory predictions and observations. The effectiveness and accuracy of the proposed method is verified by offline evaluation using a collected dataset, as well as online evaluation that the humanoid robotic table tennis system "Wu & Kong" successfully hits the high-speed spinning ball.

Sustainable care of textile products and its environmental impact: Tumble-drying and ironing processes

Despite the growing attention on sustainable consumption of textile and apparel products, little information is available for consumers guiding their decisions for sustainable consumption and product care. The objective of this study is to develop the logical processes to assess the environmental and economic impacts made by the textile product care and to measure the CO2 eq. and utility cost during drying and ironing procedures. Particularly, the influence of quick-drying property and durable-press finish on product care and their impacts on CO2 eq. and utility cost were evaluated. Results indicated quick-drying and hydrophobic fibers consumed less electricity during tumble-drying as it contained less amount of water after spinning for dehydration. A higher spin speed was favorable for saving energy during tumble-drying, as less water remained in wet laundry after spinning. While cotton fabrics were obviously wrinkled after laundering, a polyester/cotton blend in 65/35 with durable-press finish maintained smoothness grade 4 or 5 during ten times laundering period. With a conservative criterion where a grade lower than 5 needs ironing, a polyester/cotton 65/35 with durable-press finish was judged to need ironing once in two cycles of laundering. This can save about 64 % of utility and CO2 eq. that the cotton fabric would produce in the ironing process. It is anticipated that this study provides information that is useful to consumers in their decision making for sustainable consumption.

Enhanced grain refinement of in situ CeB6/Al composite inoculant on pure aluminum by microstructure control

In situ CeB6/Al composite has been proven to be an effective refiner for commercial pure aluminum, however, it remains unclear as to the mechanisms of synthesis and grain refinement. We use low-temperature alloying and high-speed melt spinning to optimize the microstructure of CeB6. It is found that in situ CeB6/Al composite shows controllable microstructure and its refining effect is obviously dependent on the size of CeB6 particle/cluster. As nano-CeB6 particles self-assemble into submicron clusters, the inoculant shows significantly enhanced refining effect, reducing the grain size of pure aluminum to ∼110 μm. The refining mechanism is attributed to the combining effect of the cluster structure in submicron scale and the excellent crystallography matching relationship of CeB6 and Al. Mechanical properties of pure aluminum are also improved by addition of in situ CeB6/Al composite inoculant due to collaboration effect of dispersion strengthening and grain refining strengthening.

Time-stretch microscopy on a DVD for high-throughput imaging cell-based assay.

Cell-based assay based on time-stretch imaging is recognized to be well-suited for high-throughput phenotypic screening. However, this ultrafast imaging technique has primarily been limited to suspension-cell assay, leaving a wide range of solid-substrate assay formats uncharted. Moreover, time-stretch imaging is generally restricted to intrinsic biophysical phenotyping, but lacks the biomolecular signatures of the cells. To address these challenges, we develop a spinning time-stretch imaging assay platform based on the functionalized digital versatile disc (DVD). We demonstrate that adherent cell culture and biochemically-specific cell-capture can now be assayed with time-stretch microscopy, thanks to the high-speed DVD spinning motion that naturally enables on-the-fly cellular imaging at an ultrafast line-scan rate of >10MHz. As scanning the whole DVD at such a high speed enables ultra-large field-of-view imaging, it could be favorable for scaling both the assay throughput and content as demanded in many applications, e.g. drug discovery, and rare cancer cell screening.

27Al MQMAS of the δ-Al13-Keggin

One-dimensional 27Al, 23Na Magic-Angle-Spinning (MAS) NMR and 27Al Multiple-Quantum Magic-Angle-Spinning NMR (MQMAS) measurements are reported for the δ-isomer of the Al13 Keggin structure at high spinning speed and 14.1 T field. Values for the CQ and η parameters are on the same scale as those seen in other isomers of the Al13 structure. Density functional theory (DFT) calculations are performed for comparison to the experimental fits using the B3PW91/6-31+G* and PBE0/6-31+G* levels of theory, with the Polarizable Continuum Model (PCM).

Fiber Structure Development of PHBH through Stress-Induced Crystallization in High-Speed Melt Spinning Process

Fiber Structure Development of PHBH through Stress-Induced Crystallization in High-Speed Melt Spinning Process

A Micro-Doppler Modulation of Spin Projectile on CW Radar

To obtain the spin speed of projectile effectively, a micro-Doppler modulation model of rotating projectile measured by continuous-wave radar (CW radar) is introduced. High spin speed of projectile brings micro-Doppler modulation on echoes of CW radar, and there are many micro-Doppler modulation harmonic waves in the zero intermediate frequency (ZIF) echoes. The frequency interval of the adjacent harmonic waves is several times of rotational frequency, but the integral multiple is unknown. The simulation results prove correctness of the proposed mathematic model.

Rheological properties of PA6 chips with different spinnability in high-speed spinning

In view of the significant differences in spinnability, BASF PA6 chips (BASF, Germany, stable in high-speed spinning) and domestic PA6 chips (GC, China, unstable in high-speed spinning) were employed. The screw extrusion process of PA6 melt in high-speed spinning was simulated by capillary rheometer, with the aid of which shear rheology and extensional rheology of PA6 chips were both investigated deeply. To determine suitable and reliable experimental conditions, the influencing factors including moisture of PA6 chips, capillary disassembly and experiment repeatability on rheological results were also discussed. The moisture of PA6 chips is confirmed to be a crucial factor and the shear viscosity and extensional viscosity of GC chips are both greater than that of BASF chips. Moreover, the shear viscosity of GC chips increases with the extension of melting time, while that of BASF chips is basically unchanged, showing good spinnability in high-speed spinning.

Decoupling Control of Micromachined Spinning-Rotor Gyroscope with Electrostatic Suspension.

A micromachined gyroscope in which a high-speed spinning rotor is suspended electrostatically in a vacuum cavity usually functions as a dual-axis angular rate sensor. An inherent coupling error between the two sensing axes exists owing to the angular motion of the spinning rotor being controlled by a torque-rebalance loop. In this paper, a decoupling compensation method is proposed and investigated experimentally based on an electrostatically suspended micromachined gyroscope. In order to eliminate the negative spring effect inherent in the gyroscope dynamics, a stiffness compensation scheme was utilized in design of the decoupled rebalance loop to ensure loop stability and increase suspension stiffness. The experimental results show an overall stiffness increase of 30.3% after compensation. A decoupling method comprised of inner- and outer-loop decoupling compensators is proposed to minimize the cross-axis coupling error. The inner-loop decoupling compensator aims to attenuate the angular position coupling. The experimental frequency response shows a position coupling attenuation by 14.36 dB at 1 Hz. Moreover, the cross-axis coupling between the two angular rate output signals can be attenuated theoretically from −56.2 dB down to −102 dB by further appending the outer-loop decoupling compensator. The proposed dual-loop decoupling compensation algorithm could be applied to other dual-axis spinning-rotor gyroscopes with various suspension solutions.

Process–structure–property relationship of melt spun poly(lactic acid) fibers produced in the spunbond process

ABSTRACTWe report on the process–structure–property relationships for Poly(lactic acid) (PLA) filaments produced through the spunbond process. The influence of spinning speed, polymer throughput, and draw ratio on crystallinity and birefringence of fibers were evaluated. We established that increasing spinning speed increases crystallinity and birefringence of fibers. We also investigate the role of fiber structures on fiber tensile properties—breaking tensile strength, strain at break, initial modulus, and natural draw ratio. An increase in spinning speed leads to a higher breaking tensile strength, higher initial modulus and lower strain at break. We have shown an almost linear relationship between breaking tensile strength of PLA fibers and birefringence. This indicates that improved tensile properties at high spinning speeds can be attributed to enhanced molecular orientation. The dependency of fiber breaking tensile strength and strain at break on spun orientation were explained with natural draw ratio, as a measure of spun orientation. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44225.

Theoretical analysis of the yarn fracture mechanism of self-twist jet vortex spinning

According to the yarn mechanism of self-twist jet vortex spinning, this article analyzes the structure and the fracture mechanism of self-twist jet vortex spinning yarn. Combined with experiments, this article established that the fiber in self-twist jet vortex spun yarn has self-twist, which increases the mutual contact area and the cohesion between the fibers in the yarn. This is helpful to improve the evenness and tensile properties of jet vortex spun yarn. The self-twist jet vortex spinning can keep the high spinning speed of the jet vortex spinning at the same time. The research on self-twist jet vortex spinning lays the foundation for the research and the development of jet vortex spinning.

Wet Chemical Etching Behavior Investigation for CMOS Shallow Trench Isolation (STI) Shape Control

Shallow trench isolation (STI) divot shape control is always one of most key logic process in semiconductor fabrication. Conventional wet chemical treatment easily cause deep divot and result in transistor kink effect of drain current (Id) v.s. gate voltage (Vg) relation curve. Gas phase chemical etching method can reduce divot level around 55% compared with conventional wet batch type dilute HF (DHF) etching. This study indicated that divot formation is highly correlated to etching surface geometry, chemical boundary layer thickness and chemical flow speed. By etching method selection and parameter adjustment, divot can be controlled in logic process.Shallow trench isolation (STI) divot profile usually affects MOS transistor electrical properties, such as drain current (Id) versus gate voltage (Vg) double hump curve (kink effect), due to parasitic transistor formation. Slightly STI divot is acceptable in most logic processes. However, it is observed that under the same STI SiO2 etching amount, gas phase chemical etching divot level is around 55% reduced by comparing with conventional batch type wet chemical (dilute HF) etching, showed in Figure 1.Divot levels difference between gas phase etching method and conventional wet etching method was observed. In this study, some key points had been defined, showed as Figure 2, to monitor STI SiO2 loss phenomenon during different etching methods. Point a is STI vertical top SiO2 loss amount; point b is STI sidewall top SiO2 loss; point c is STI sidewall bottom SiO2 loss; b/a is the SiO2 loss ratio of STI sidewall top to vertical top; c/a is the SiO2 loss ratio of STI sidewall bottom to vertical top.To figure out the behavior of STI SiO2 loss, single wafer spin wet etching method was added and split three spin speed conditions as 800rpm, 1500rpm and 2200rpm. Figure 3. showed TEM images of STI etching by gas phase, batch type DHF and spin type DHF process. Table 1 and Figure 4 showed a, b, c values of above etching methods.Normally, isotropic etching rate will be affected by geometry effect. Larger etched surface exposed results in higher etching rate due to different surrounding reactant amount, showed as Figure 5. That means the ratio (c/a) of STI vertical top SiO2 loss to sidewall bottom SiO2 loss should be less than 1 theoretically, which had been observed in batch DHF etching method.However, from Figure 4, spin type DHF etching method showed c/a ratio larger than 1. Based on Bernoulli's effect, reactant (HF2 -) at STI top will be dragged down to the STI sidewall bottom area due to higher DHF flow speed in small tunnel area. Higher flow speed induced thinner boundary layer, and sufficient reactant makes STI sidewall bottom etching rate increasing. The mechanism showed as Figure 6. By increasing spin speed from 800rpm to 2200rpm, c/a ratio changed from 1.13 to 1.03, approaching to batch type value 0.91. Higher spin speed also increased DHF flow speed at STI top and minimized the flow speed difference between STI top and sidewall bottom.For gas phase chemical etching, HF and NH3 mixing gas is usually used for SiO2 etching, and byproduct (NH4)2SiF6 is generated and deposit on SiO2 surface which will interfere following reactants diffusing toward SiO2 surface for further etching reaction. As byproduct thickness increasing, finally, etching stop due to no reactants touching fresh SiO2 surface. The mechanism showed in Figure 7. c/a ratio less than 1 can also be found in gas phase etching method, and much less than 1 due to the combination effect of geometry and byproduct interfering.Table 2 showed each etching method characteristics and merit/ demerit, gas phase etching has no water mark issue and has well divot control capability. Both batch type and spin type DHF etching methods have water mark risk, but spin type DHF etching method can prevent wafer surface particle redeposit.Spin type wet etching process becomes mainstream in semiconductor foundry due to excellent particle defect performance, but higher chemical flow speed inducing higher etching rate in STI SiO2 small tunnel and causing deeper divot, although increasing spin speed can minimized the divot level. Gas phase type etching has intrinsic diffusion barrier of etching byproduct. Combining gas phase and DHF etching methods for all STI SiO2 etching processes can get expected final divot profile or only using gas phase etching method can achieve excellent divot control capability in logic 28nm generation or more advanced MOSFET fabrication processes. Figure 1

Study on the Characterization and Evaluation Methods of PA6 Chips for High-Speed Spinning

Abstract The reasons for the significant difference of PA6 spinnability are discussed. For this research project, BASF PA6 chips (BASF, Germany) and PA6 chips (GC, China) were chosen as research objects. We chose these two different chips because BASF PA6 chips are stable and GC PA6 chips are unstable in high-speed spinning. The measurement of relative viscosity, crystallization rate, content of extractable matter, molecular weight and its distribution, and Fourier transform infrared (FTIR) spectroscopy of extractable matter were systematically investigated. Moreover, the screw extrusion process of PA6 melt in high-speed melt spinning was simulated by a capillary rheometer, in which PA6 samples with different melting times were prepared to conduct the above-mentioned tests. Compared to BASF chips, the GC chips have the higher content of extractable matter, the greater and more variable relative viscosity, the greater molecular weight, and the wider distribution, causing the poorer spinnability in high-speed spinning. Furthermore, the extractable matter in GC chips is the same as that in BASF chips, which is confirmed by FTIR spectra.

Similarities and Differences in Structure Formation Processes in Polyester Yarns During Orientational Drawing and High-Speed Spinning. Review

We demonstrate the similarities and differences between formation of structural and mechanical properties of polyethylene terephthalate (PET) yarns during drawing and during high-speed spinning (HSS). The orientational drawing process enables a targeted change in structural and mechanical properties of PET yarns. In high-speed spinning, a targeted change in the properties of the yarns to the level attainable in orientational drawing is not possible due to the non-isothermal nature of the process. Studies have shown that the structure formation conditions for the indicated processes need to match better in order to develop an optimized one-step process for obtaining PET textile yarns.

Allergy Testing and Drug Screening on an ITO-Coated Lab-on-a-Disc.

A lab-on-a-disc (LOAD) is a centrifugal microfluidic set-up based on centrifugal force without using micro-pumps to drive reagents and cells to various chambers through channels and valves for reactions. A LOAD coated with conductive transparent indium tin oxide (ITO) for thermal control was developed to screen allergy-blocking agents. When the acridine orange (AO)-loaded KU-812 human basophilic cells were activated in the LOAD by stimuli, AO trapped in the cytoplasmic granules was released externally as an allergic mediator mimetic to report degranulation. This response was monitored by fluorescence when the released AO in supernatant had been transferred, with a higher spinning speed, from the reaction chamber to detection chamber in the LOAD where AO reacted with exogenous DNA. We report here the principles of the system and an improved LOAD set-up with the ITO-coated glass resistive microheater to run assays at 37 °C. By using this platform, we demonstrate here for the first time that triptolide, an active ingredient from the Chinese medicine herb Tripterygium wilfordii Hook f., was able to suppress the fMLP-mediated degranulation in basophils. This serves as an example how LOADs can be used to screen agents to alleviate symptoms of allergy.

Development of 3D microvascularized gelatin hydrogel for skin tissue engineering

Event Abstract Back to Event Development of 3D microvascularized gelatin hydrogel for skin tissue engineering Jung Bok Lee1, 2, Shannon Faley2, Hak-Joon Sung1 and Leon M. Bellan1, 2 1 Vanderbilt University, Biomedicl engineering, United States 2 Vanderbilt University, Mechanical Engineering, United States Introduction: Numerous strategies have been approached to regenerate skin defects resulting from burns, trauma, or non-self-healing chronic wounds.[1][2] Among the various types of scaffolds employed, hydrogels, consisting of natural or synthetic polymers with high water content, have been widely used as engineered tissue constructs for skin regeneration due to their tunable properties to mimic extracellular matrix (ECM).[3][4][5] Despite of continuous progress, a significant challenge still remains in using hydrogels to produce tissue constructs due to inefficient delivery of nutrients and oxygen to cells embedded deep within the hydrogels. The aim of the current study is to investigate whether perfusion through microfluidic hydrogels improves cell survival in co-culture of human umbilical vein endothelial cells (HUVECs) and human neonatal dermal fibroblasts (HNDF), an in vitro model of skin tissue. We fabricated 3D microvascular networks in gelatin hydrogels using thermo-responsive sacrificial poly(N-isopropylacrylamide) (PNIPAM) microfibers. These microchannels allow constant perfusion of culture media throughout the hydrogel, and significantly improve the viability and proliferation of embedded HUVECs and HNDF. These perfused co-culture models will prove useful in highlighting key factors associated with the development of 3D vascularized, tissue engineered construct for skin regeneration. Materials and Methods: To make microchannels in gelatin hydrogels, PNIPAM fibers were obtained by high-speed spinning of 50% w/v PNIPAM solution in methanol. To fabricate cell-laden gels, 10 % w/v gelatin in PBS was prepared and mixed with red fluorescent protein-expressing HNDF (RFP-HNDF) (5x106 cells/ml) and 2.5 w/v% microbial transglutaminase (mTG), a crosslinking mediator. Gelatin solution containing RFP-HNDF and mTG was cast into PDMS molds with spun PNIPAM fibers and gelled with crosslinking at 37 ºC. PNIPAM fibers were then removed by continuously shaking and perfusing DMEM into the hydrogel at room temperature, thereby introducing microchannels. Next, a high concentration of HUVECs constitutively expressing green fluorescent protein (GFP-HUVEC) were injected into the microchannels in suspension (seeding density: 5 million cells in 100 μl) to seed the inner channel surface. The gelatin hydrogel was then connected to a peristaltic pump to apply gentle media flow. Results and Discussion: The microchannels were interconnected with formation of a network, as visualized by perfusion of Fluospheres into macrochannels in the hydrogel (Fig 1A). The media perfusion allowed HNDF to spread, elongate and form cell networks after 7 days of culture (Fig. 1C) whereas the lack of media perfusion inhibited this HNDF behavior (Fig.1B). The media perfusion enhanced exchange of necessary soluble compounds, as seen from cell viability data. Conclusion: This study demonstrated the feasibility of making PNIPAM microfibers and using these as sacrificial templates to obtain interconnected microchannels in gelatin scaffolds. Cell culture studies showed improved cell viability and stretched cell morphology with cell network formation in this perfused system. The results suggest this perfusable gelatin hydrogel system supports co-cultured HUVECs and HNDF cells, indicating significant potential to apply for engineering soft tissues including skin tissues. Figure 1. A confocal microscope image of microchannels in the gelatin hydrogel (3D image) (A) and confocal microscope images of HUVECs (green) and HNDF (red) in the gelatin hydrogel without perfusion (B) and with perfusion (C) after 7 days culture. NIH R00EB013630 (to L.M.B); AHA Grant-in-Aid 15GRNT25710148 (to L.M.B. and H-J. S.); NSF 1506717 (to H-J. S. and L.M.B.); NIH EB019509 (to H-J.S)