Viscosity Measurement Methods Research Articles

Data-Driven and Machine-Learning-Based Real-Time Viscosity Measurement Using a Compliant Mechanism

In this work, a novel method of viscosity measurement is proposed using a device comprising a compliant mechanism, a vibration source, and a piezoelectric sensor. The vibration source creates linear harmonic vibrations in the compliant mechanism suspended in the liquid, and the acceleration response of the mechanism is measured using the piezoelectric sensor. The vibration source is located in the central mass of the compliant mechanism, which is designed to have the necessary directional stiffness. As the mechanism vibrates, the links in the mechanism undergo damping due to the shearing action of the fluid because of its viscosity. A series of viscosity measurements are carried out with the use of water–glycerol solutions such that the acceleration of the mass is influenced by the fluid’s viscosity. During the working of the device, the mechanism is immersed in the liquid whose viscosity is to be measured. The acceleration response of the mass is recorded as time domain data using NI Lab View hardware and software, which are used to train a machine learning model. Later, a regression-based machine learning model is used for the estimation of dynamic viscosity for the given acceleration input. Experiments are performed with the prototype device using the water–glycerol solution within a viscosity ranging from 10 cP to 60 cP. The proposed sensor can be used for in-line measurements or used as a handheld instrument for quick measurements. The machine learning model achieved a high level of accuracy, evidenced by an R-squared value of 0.99, indicating that it explains 99% of the variance in the data.

A comparative study of blood viscometers of 3 different types.

The greater the viscosity of the blood, the more difficult its flow becomes, leading to an increased incidence of diseases caused by blood circulation disorders. These diseases are commonly associated with the cardiovascular and cerebrovascular systems. High blood viscosity is a primary cause of circulatory system diseases. Studies have shown that accurately measuring blood viscosity and applying this data in clinical trials can help prevent circulatory system diseases. Viscosity data can vary depending on the measurement methods used, even when these methods are based on hydrodynamic principles. Despite using approved blood viscometers, the results often differ depending on the type of viscometer used, potentially causing confusion within the medical field. Informing the medical community about these differences and the level of error associated with each measurement method can help reduce this confusion. To our knowledge, the degree of difference in viscosity measurement results due to different measurement methods and the reasons for these differences have not yet been thoroughly explored. In this study, we selected three blood viscosity measurement methods registered with the Ministry of Food and Drug Safety of Korea to analyze the same canine blood. The viscosity measurements were carried out using each device and compared. The parallel plate and scanning capillary methods yielded similar viscosity values, while the cone plate method showed lower viscosity values. The viscosity of blood, as measured by the three viscometers, differed, indicating that more experimental data must be accumulated to evaluate the cause of these differences. In this paper, we identified several causes of inconsistency and suggested measures to avoid this confusion. However, confirming that the test results show systematic differences is expected to assist clinicians who diagnose and prescribe treatments based on blood viscosity results. The findings of this comparative study are anticipated to serve as a starting point for establishing guidelines or standards for blood viscosity measurement methods.

A rapid and non-immersed method of viscosity measurement with small-volume samples based on longitudinal guided waves in capillary

Viscosity measurement is crucial in medical diagnostics, pharmaceuticals, and analytical chemistry, where samples are frequently in small volumes and measurements are supposed to be conducted in a short time with convenient approaches. In this study, we propose a viscosity measurement approach based on longitudinal guided waves with a dominant in-plane displacement. The viscosity is determined using the attenuation of longitudinal guided waves in a liquid-filled capillary. The use of guided waves accelerates the measurement while the application of a capillary reduces the sample volume. Additionally, the approach is nondestructive and repeatable since the liquid sample is injected into the capillary instead of immersing the probe into the liquid; the sample is located in a relatively closed tube, reducing the interferences of outside factors. In our propomsed method, the sample volume is only 176.6 μL and the measurement time of one sample is only 5.6 ms. The effectiveness and practicability of the proposed approach is confirmed by measuring silicon oils with viscosities from 9.01 mPa·s to 532 mPa·s and a limit of detection (LOD) of 0.97 mPa·s. The minimum error is about 5 % at 442 mPa·s and the maximum error is about 18 % at 9.01 mPa·s Besides, the approach was employed for detection of viscosity in artificial tear samples, which indicated that satisfactory applicability was achieved. This work not only demonstrates the judicious design of a rapid and non-immersed method for viscosity measurement, but also a promising scheme for point-of-care analysis of tear viscosity, thus offering great potential for at-home diagnosis and personalized healthcare of various ocular diseases.

Microfluidic Rheology: An Innovative Method for Viscosity Measurement of Gels and Various Pharmaceuticals.

Measuring the viscosity of pharmaceutical dosage forms is a crucial process. Viscosity provides information about the stability of the composition, the release rate of the drug, bioavailability, and, in the case of injectable drug formulations, even the force required for injection. However, measuring viscosity is a complex task with numerous challenges, especially for non-Newtonian materials, which include most pharmaceutical formulations, such as gels. Selecting the appropriate shear rate is critical. Since viscosity in many systems is highly temperature-dependent, stable temperature control is necessary during the measurement. Using microfluidics technology, it is now possible to perform rheological characterization and conduct fast and accurate measurements. Small sample volumes (even below 500 µL) are required, and viscosity determination can be carried out over a wide range of shear rates. Nevertheless, the pharmaceutical application of viscometers operating on the principle of microfluidics is not yet widespread. In our work, we compare the results of measurements taken with a microfluidic chip-based viscometer on different pharmaceutical forms (gels, solution) with those obtained using a traditional rotational viscometer, evaluating the relative advantages and disadvantages of the different methods. The microfluidics-based method enables time- and sample-efficient viscosity analysis of the examined pharmaceutical forms.

Exploring tear viscosity with quartz crystal microbalance technology.

Tear viscosity is a critical property affecting tear distribution and ocular surface stability. While not widely established as a primary diagnostic marker, deviations from normal viscosity can impact ocular health, potentially contributing to conditions such as dry eye syndrome. Despite their importance, traditional viscometers require sample volumes that are not feasible to use with tear volume. This research introduces a novel Quartz Crystal Microbalance (QCM)-based method for tear viscosity measurement, offering a viscometer prototype that operates with minimal sample volumes. Human tear samples, solutions used in artificial eye drops, and various commercial eye drop brands were evaluated. Results show that the QCM method aligns with established viscosity ranges. The average viscosity of healthy human tears was found to be 1.73 ± 0.61 cP, aligning with the typical range of 1-10 cP. Variability in the viscositiesof eye drop can be attributed to differences in their chemical compositions. The QCM method offers benefits such as reduced sample consumption and rapid results, enhancing understanding of tear dynamics for ocular health. Further research with larger sample sizes is needed to establish normative viscosity values in healthy individuals and those with dry eye syndrome, which is crucial for validating the device's clinical efficacy.

Fluid viscosity prediction leveraging computer vision and robot interaction

Accurately determining fluid viscosity is crucial for various industrial and scientific applications. Traditional methods of viscosity measurement, though reliable, often require manual intervention and cannot easily adapt to real-time monitoring. With advancements in machine learning and computer vision, this work explores the feasibility of predicting fluid viscosity by analyzing fluid oscillations captured in video data. The pipeline employs a 3D convolutional autoencoder pretrained in a self-supervised manner to extract and learn features from semantic segmentation masks of oscillating fluids. Then, the latent representations of the input data, produced from the pretrained autoencoder, are processed with a distinct inference head to infer either the fluid category (classification) or the fluid viscosity (regression) in a time-resolved manner. When the latent representations generated by the pre-trained autoencoder are used for classification, the system achieves a 97.1% accuracy across a total of 4140 test datapoints. Similarly, for regression tasks, employing an additional fully-connected network as a regression head allows the pipeline to achieve a mean absolute error of 0.258 cP over 4416 test datapoints. This study represents an innovative contribution to both fluid characterization and the evolving landscape of Artificial Intelligence, demonstrating the potential of deep learning in achieving near real-time viscosity estimation and addressing practical challenges in fluid dynamics through the analysis of video data capturing oscillating fluid dynamics.

Modeling of ionic liquids viscosity via advanced white-box machine learning.

Ionic liquids (ILs) are more widely used within the industry than ever before, and accurate models of their physicochemical characteristics are becoming increasingly important during the process optimization. It is especially challenging to simulate the viscosity of ILs since there is no widely agreed explanation of how viscosity is determined in liquids. In this research, genetic programming (GP) and group method of data handling (GMDH) models were used as white-box machine learning approaches to predict the viscosity of pure ILs. These methods were developed based on a large open literature database of 2813 experimental viscosity values from 45 various ILs at different pressures (0.06-298.9MPa) and temperatures (253.15-573K). The models were developed based on five, six, and seven inputs, and it was found that all the models with seven inputs provided more accurate results, while the models with five and six inputs had acceptable accuracy and simpler formulas. Based on GMDH and GP proposed approaches, the suggested GMDHmodel with seven inputs gave the most exact results with an average absolute relative deviation (AARD) of 8.14% and a coefficient of determination (R2) of 0.98. The proposed techniques were compared with theoretical and empirical models available in the literature, and it was displayed that the GMDH model with seven inputs strongly outperforms the existing approaches. The leverage statistical analysis revealed that most of the experimental data were located within the applicability domains of both GMDH and GP models and were of high quality. Trend analysis also illustrated that the GMDH and GP models could follow the expected trends of viscosity with variations in pressure and temperature. In addition, the relevancy factor portrayed that the temperature had the greatest impact on the ILs viscosity. The findings of this study illustrated that the proposed models represented strong alternatives to time-consuming and costly experimental methods of ILs viscosity measurement.

Temperature dependence of polymer melt viscosity obtained based on DSC data and the consistency between thermodynamic and kinetic fragility

AbstractThe viscosity of the polymer melt has an impact on both the processing and properties of the product. However, conventional viscosity measurement methods have limitations such as strict testing conditions, large sample sizes, and long response times. This paper proposes a simplified method that utilizes differential scanning calorimetry to determine the viscosity–temperature relationship of the polymer melt. The research subjects consist of four noncrystalline polymers and five crystalline polymers. A new thermodynamic fragility formula of crystalline polymer is obtained. Additionally, high‐temperature limiting viscosity shows a good linear relationship with fragility. Compared with the traditional viscosity measurement, this method is a simpler and more effective way to model the viscosity of polymer melt and has broad prospects in application.

Electromagnetically spinning viscometer designed for measurement of low viscosity in low shear rate region

The electromagnetically spinning method for measurement of fluid viscosity was improved to obtain accurate values of low viscosity in the low shear rate region. Harmful effects derived from the mechanical friction to the smooth rotation of the rotor are thoroughly eliminated by employing a viscosity probe suspended by a thin metal wire. In our previous study, the motion of the meniscus of the sample surface also acted as a troublesome resistant torque for probe rotation, which was addressed by employing a sandwiched structure of the disk probe between the bottom and top plates. The measurements were carried out in two procedures. In the freely oscillating operation, we could measure the viscosity of the atmosphere with a viscosity of approximately 1/100 of that of water. The second type of quasi-steady measurement enabled a measurement of pure water in the range of shear deformation rates smaller than 1 s−1.

Dynamic Viscosity Measurement Method Based on the Stokes Drag of Prolate Ellipsoidal Mass

Viscometer plays an important role in the field of tribology. One way to measure viscosity is to use the Stokes drag principle in the underdamped harmonic oscillation phenomenon. This paper proposes a dynamic viscosity measurement method based on the related physical laws. Our experimental model involves a prolate ellipsoidal mass that experiences underdamped harmonic oscillation within viscous liquid samples. We observed the oscillations of the prolate ellipsoid to obtain the viscous damping coefficient of each sample and substituted it to the theoretical formula of dynamic viscosity. Experimental data suggest that the mathematical model has failed to predict the viscosity values of the samples. In addition, the regression curve of the reference viscosity and the measured viscous damping coefficient shows that the two quantities have an exponential relation instead of linear relation as explained in the theoretical model. We considered the regression formula as the empirical measurement transfer function and used it to measure the viscosity of an ISO VG 150 industrial oil sample. This measurement resulted in a 2.40 % of relative error percentage. Lastly, this measurement method is only valid for measuring samples with viscosities ranging from 0.0400 Pa s to 0.256 Pa s.

Temperature corrections for coaxial cylindrical viscosity measurement method on molten salt

Modern industrial applications often require accurate measurements of high temperature fluids such as molten salts. However, the commonly used coaxial cylindrical viscosity measurement method has an intrinsic bias when the calibration fluid and test fluid are run at significantly different temperatures due to the thermal expansion of solid container materials. In this study, we take a novel approach by deriving and quantifying the thermal expansion bias, β, for various common container materials using fluid dynamics arguments, thermal expansion data, and empirical methods. To the best knowledge of the authors, this work represents the first quantification of the thermal expansion bias and fills a significant gap in the current understanding. To validate our findings, we conducted an experiment on solar salt and applied the derived thermal expansion correction to the results, comparing them to independent studies. The results highlight the importance of the thermal expansion correction, which increases with rising temperature, particularly in high thermal expansion materials such as stainless steel, which has a bias of ∼6 % at 1000 °C. Our contribution provides valuable insights into the accurate measurement of high temperature fluids and offers a substantial advancement in addressing the thermal expansion bias, setting a new standard for future research in this field.

Evaluation of the in vitro performance of generic and original adapalene gel

Objective The aim was to evaluate the difference of the in vitro behavior between the commercially available generic adapalene gel and original product with Topical Classification System (TCS), and to analyze the effect of changes of excipients on the release behavior. Significance Establishing in vitro performance assays to understand the impact of formulation variables on the critical quality attributes (CQA) is critical for the quality assessment of semi-solid generic drug. Methods In vitro release (IVR), in vitro permeation (IVP), viscosity, and pH measurement methods for adapalene gels were established and validated. The differences between generic adapalene gel from 7 companies and original products were evaluated by correlation analysis (CA) and principal component analysis (PCA), and the relationship among 4 parameters was elucidated. The effect of excipients on the above variables was examined by univariate tests. Results There were some differences between the gels of 5 of the 7 imitation enterprises and reference listed drug (RLD). There were varying degrees of correlation between viscosity, pH, the adapalene amount retained in skin and release rate. The result validated the key role of IVR, and identified that pH value, type of suspending agent, the amount of carbomer, etc. had certain effects on the release rate. Conclusions The factors mentioned above should be considered when developing and manufacturing generic adapalene gels, and the application of TCS in the evaluation of generic topical drugs was advanced. Additionally, our research revealed some discrepancies from USP<1724>, which could be valuable information for the revision.

Investigation of a Finite-Difference-Method based real-time viscous heating compensation in a nozzle viscometer for inline viscosity measurement of phenol resins

This work is motivated by the rarely available material data for thermosets and a missing inline viscosity measurement method to monitor melt property deviations. A nozzle viscometer is designed for inline viscosity measurement of phenol-formaldehyde compounds. The nozzle viscometer is mounted at the plasticizing unit of an injection molding machine. A fluid coolant circuit allows a dynamic tempering to pause the transient crosslinking reaction. A 2D FDM model is implemented, to calculate the viscous heating within an injection cycle and to compensate the temperature rising effect in the viscosity measurement. The FDM model processes the inline sensor signals in a closed loop correction in real time to determine a corrected reactive viscosity model. The signal-to-noise-ratio quantifies the reliability of the inline viscosity measurement method.

U-shaped optical microfiber-based liquid viscosity measurement

In recent years, viscosity sensors have gained widespread applications. However, their high production costs and inability to achieve online measurement have limited their practical use. To overcome these limitations, we propose a novel viscosity measurement method based on optical microfiber. The sensor comprises a U-shaped optical microfiber encapsulated in a PDMS film. Under identical motion speeds in liquids with different viscosities, the optical microfiber bends to varying degrees, causing changes in the transmittance that are directly related to solution viscosity. The performance of the sensor can be adjusted by changing cantilever thickness, optical microfiber diameter, and light source wavelength. To obtain a curve that showing the relationship between transmittance and viscosity, the sensor is calibrated using solutions of known viscosity. Finally, we demonstrate the effectiveness of the method by comparing theory with experiment through testing experiments. By using this method, we achieved accurate viscosity measurements in the range of 10–50 mPa·s, with errors of all test samples less than 3.8%. Overall, this novel optical microfiber based method offers a promising solution for practical and cost-effective viscosity measurements.

Experimental viscosity monitoring in complex pipe systems for flows of drilling muds based on the energy dissipation rate

This study aimed to measure the viscosity of non-Newtonian fluids (xanthan gum solution and drilling muds) in-situ during complex pipe flows using pressure drop and flow rate data without sampling. This method of viscometry can be applied to various inelastic non-Newtonian fluids and pipe systems of general geometries, including shear-thinning fluids (such as xanthan gum) and viscoplastic fluids with yield stress (drilling mud), as long as the flow rate and pressure drop within the system can be measured in-situ. The method employs two flow numbers (energy dissipation rate coefficient and effective shear rate coefficient) that are mainly determined by the flow geometry, nearly independent of the rheological behavior of a fluid. The representative effective shear rate for a given system is determined by the effective shear rate coefficient and flow rate; and the relationship between effective viscosity and material viscosity was found to be identical. The method was validated with three different non-Newtonian fluids in three different lab-scale complex pipe systems, including a straight circular pipe with connectors, a pipe system with an intermediate branch, and a 3D pipe system with height and slope variations. The accuracy assessment of viscosity measurement and pressure drop prediction showed no more than an 18.7% error in all the cases. The in-situ viscosity measurement method presented in this study can be used for process monitoring and process quantification of non-Newtonian fluid flows in various types of pipe flows used in industrial processes.

A structure-oriented elucidation for viscous flow of SiO2-MnO-Al2O3 fused submerged arc welding fluxes

Understanding the physiochemical properties of flux is critical to addressing the challenges towards developing high heat input welding flux. In this study, the viscous behavior and structure of ternary SiO2-MnO-Al2O3 submerged arc welding fluxes were investigated using the rotating cylinder method for viscosity measurement, Raman spectroscopy and X-ray photoelectron spectroscopy for structure analysis. The results showed that the viscosity increased with the substitution of MnO with Al2O3, which is correlated to the enhancement in the degree of polymerization of the flux as the activation energy increased from 71.36 to 119.71 kJ/mol with increasing Al2O3 content from 0 to 20 wt.pct. The enhanced (Q2+Q3+Al-O0)/(Q0+Q1+Al-O+AlO6) ratio indicated the continuous polymerization of the flux structure, which was further confirmed by the distribution characteristics of various oxygen species and thermodynamic analysis.

Application of EMS system for continuous measurement of rheology in reaction chamber

The electromagnetically spinning method for viscosity measurement was enhanced for applications in a confined reaction chamber. In the reaction chamber, the immersion of the rotor into the sample might trigger the precipitation and aggregation of ingredients to the pivot of the probe rotor, which leads to harmful frictional torque of the rotation. To address this problem, an upper-point-type auto-standing probe rotor was developed and applied for the long-term measurement of the solution process of rock sugar in water. In addition, we propose the adoption of a punched board, instead of a solid board, as the lower substrate of the plate-plate-type rotational viscometer, which allows rapid exchange of the sample fluid between the interior and exterior of the narrow measurement area through molecular diffusion. We investigated the effect of punches from the perspective of the diffusion process of momentum and determined the geometrical conditions.

In-line measurement of multiphase flow viscosity

The transportation modes depend entirely on the viscosity of the oil. To date, none of the viscometric methods are able to provide measurements to meet all the requirements of oil flow, features of main oil pipelines, and trends in the oil industry, such as decarbonization and digitalization. The method of inline viscosity measurement of multiphase flow through a metal pipeline can be based on direct gamma ray measurement. It is stipulated by the ability of gamma-radiation to penetrate through the pipeline material without destroying it, as well as by the ability to work with flows containing free gas and the high capability to be introduced into automatic control systems. The authors consider the physical forces acting on the gas inclusions in the oil flow. They determine the physical dependence between the parameters determined by the radioisotope method and the viscosity of oil in the three-phase flow. These studies show good agreement with the work of other scientists. The prospect of further research will be to clarify the mathematical model of gas-oil flow, to increase the accuracy by reducing the number of assumptions made.

A method to measure non-Newtonian fluids viscosity using inertial viscometer with a computer vision system

The theory of rheology of non-Newtonian fluids is based on the generalized Newtonian hypothesis of viscosity. The viscometers for non-Newtonian fluids should implement fluid flows with the known stress and strain state parameters distributions. Ideally, the distributions should be homogeneous in the flow domain. The idea of the proposed method is based on a combination of a capillary and a rotational viscometers implemented in the torus-shaped capillary viscometer. Analysis of the mathematical model of the inertial non-Newtonian fluid flow in the torus allowed to determine the conditions of homogeneity of the mechanical and thermal parameters in the flow domain and to develop method of viscosity measurement. The measured values are the shear rate on the inner surface of the capillary and the flow rate. The measurements are implemented with the computer vision system that processes data obtained from the high speed CMOS camera that records inertial flow in the transparent capillary illuminated with laser. The computer vision system is based on the application of deep convolutional neural network for laser speckle contrast imaging processing. During the experiments, the proposed viscometer was compared with the Brookfield rotational viscometer. The relative error of the proposed viscometer and method is less than 2%. The inertial viscometer is compact, it allows to study the wide range of shear rates per one test in automatic mode, and it has low fluid capacity of approximately 1.87 ml. That makes it possible to use the viscometer as a point on care testing device in medicine to study the rheology of physiological fluids, in particular blood.

Brief Research on the Biophysical Study and Anticancer Behavior of Pt(II) Complexes: Their DNA/BSA Binding, Molecular Docking, and Cytotoxic Property.

The potent bidentate carrier ligand 2-picolylamine (pic) has been used to synthesize Pt(II) complexes to know their bioactivity and anticancer property as reflected by PASS prediction software. The dichloro Pt(II) complex [Pt(pic)Cl2], Pt-1, and its hydrolyzed diaqua complex [Pt(pic)(OH2)2]2+, Pt-2, were synthesized. The thiol-containing Pt(II) complexes [Pt(pic)(l-cys)]+, Pt-3, and [Pt(pic)(L-ac-l-cy)]+, Pt-4, were synthesized from Pt-2, which was obtained from hydrolysis of Pt-1. Their biomolecular interactions with BSA and DNA were executed by spectroscopic methods, and their cytototoxic property was tested by the MTT assay. In vitro biomolecular interactions of Pt(II) complexes with BSA and DNA were investigated by different spectroscopic and viscosity measurement methods for their pharmacokinetic and pharmacodynamic importance. The conformational change of BSA in the presence of a drug candidate was studied by Förster resonance energy transfer calculation and synchronous and three-dimensional fluorescence spectroscopic studies. A theoretical approach on optimization structures, highest occupied molecular orbital-lowest unoccupied molecular orbital energy, global reactivity parameters, time-dependent density functional theory, and molecular docking with BSA and DNA was executed to strengthen and support the experimental observations. In vitro cytotoxic profiles of the complexes like the anticancer activity and their level of reactive oxygen species production were brought under consideration on A549 cancer cells and the normal human embryonic kidney cell line HEK-293. The cytotoxic property was compared with that of the recognized anticancer drug cisplatin.