Design of a high precision falling-ball viscometer

Nanometer-scale pores have demonstrated potential for the electrical detection, quantification, and characterization of molecules for biomedical applications and the chemical analysis of polymers. Despite extensive research in the nanopore sensing field, there is a paucity of theoretical models that incorporate the interactions between chemicals (i.e., solute, solvent, analyte, and nanopore). Here, we develop a model that simultaneously describes both the current blockade depth and residence times caused by individual poly(ethylene glycol) (PEG) molecules in a single α-hemolysin ion channel. Modeling polymer-cation binding leads to a description of two significant effects: a reduction in the mobile cation concentration inside the pore and an increase in the affinity between the polymer and the pore. The model was used to estimate the free energy of formation for K þ -PEG inside the nanopore (≈ − 49.7 meV) and the free energy of PEG partitioning into the nanopore (≈0.76 meV per ethylene glycol monomer). The results suggest that rational, physical models for the analysis of analyte-nanopore interactions will develop the full potential of nanopore-based sensing for chemical and biological applications.alpha-hemolysin | nanopore-based sensing | polymer confinement | polymer analysis P olymers play a fundamental role in life (1) and are central to many emerging technologies (2). Many of these applications require a detailed understanding of the structure, morphology, and chemical interactions of polymers under confinement in either 2-dimensional films (3) or narrow tubes (4). The ability to isolate and study single molecules has shown promise in overcoming the limitations of measurements with ensemble averages and permits probing the inter-and intra-molecular forces, structural changes, and dynamics of polymers (for a detailed review of single-molecule polymer analysis see refs. 5 and 6).Molecules partition into a nanopore and alter the flow of ions resulting in distinct current blockades that can be used to detect, characterize, and quantify a wide range of polymer types (7). These include single-stranded RNA and DNA (8-10), proteins (11-14), biowarfare agents (15), therapeutic agents against anthrax toxins (15, 16), and chemically synthesized molecules (14,(17)(18)(19)(20). More recently, single nanopores were used to determine the size distribution of polymers in a manner akin to mass spectrometry (19).To fully realize the potential of nanopore-based sensors, it is important to develop a detailed understanding of the physical and chemical interactions of polymers with the nanopore, solvent, electrolyte, and other components. In this work, the interaction between poly(ethylene glycol) (PEG) and the α-hemolysin (αHL) channel in a high ionic strength electrolyte was used to develop a unique model of polymers confined within single nanopores.Previous attempts to describe the magnitude of PEG-induced nanopore current blockades focused on volume exclusion (21) and/or microviscosity (22), which required adjustable ad hoc...

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“…B depends on A PEG ∕A pore in a nontrivial way, which can only be estimated numerically (52). Here, it is part of the free parameter ξ.…”

Section: Theorymentioning

confidence: 99%

Theory for polymer analysis using nanopore-based single-molecule mass spectrometry

Reiner

Kasianowicz

Nablo

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

198

372

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“…Metode lain yang sudah dikenal sejak lama untuk mendapatkan nilai viskositas adalah metode bola jatuh (falling ball method) dengan prinsip Hukum Stokes (Gambar 1) (Leont'ev & Vakhrushev 1976;Lommatzsch et al 2001;Fujita et al 2003;Fujita et al 2005;Brizard et al 2005).…”

Section: Pendahuluanunclassified

“…Mengacu pada Gambar 1, maka berlaku persamaan berikut: Brizard et al (2005). Pengukuran dengan menggunakan perekaman citra dilakukan dengan dua tahap, yaitu: 1) perekaman, dan 2) pengolahan citra dengan melakukan perbandingan antara dua citra saat bola jatuh melewati titik referensi pertama dan titik referensi kedua.…”

Section: Pendahuluanunclassified

Desain dan Analisis Pengukuran Viskositas dengan Metode Bola Jatuh Berbasis Sensor Optocoupler dan Sistem Akuisisinya pada Komputer

2013

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It has been designed and analyzed the low cost viscometer using falling ball method, the sample analyzed is glycerin fluid at 20 o C. Two optocoupler circuits have been used as time measurement system of falling ball between two references point, light source used was infrared laser diode. The computer acquisition system use serial communication and it has been perfectly made and characterized. The velocity measurement system has 0.75 x 10 -1 s resolution, but the resolution of integrated system both of hardware and acquisition software, is about 10 -1 s. The theoretical viscosity value has been calculated and simulated to abtain the absolute viscosity value. This simulation results have been analyzed and compared with the experiment results. The correction factor for velocity calculation has been discussed and gave the optimum value of velocity correction factor (0.4425), regarding to the dimension of tube and ball used in this research. Based on the experiment, the viscosity of glycerin obtained was 1418.0309±1.6157 mPa.s., this value was with similar with the literatures and has a 0.57% of accuracy error (ε 0 ). ABSTRAKTelah didesain dan dianalisis alat ukur viskositas sederhana menggunakan metode bola jatuh, dengan sampel yang diuji adalah cairan gliserin pada suhu 20 o C. Dua rangkaian optocoupler telah digunakan untuk mengukur waktu bola jatuh antara dua titik acuan, sumber cahaya yang digunakan adalah laser dioda infra merah. Sistem akuisisi komputer menggunakan komunikasi serial dan semua sistem telah dibuat dan dikarakterisasi dengan baik. Sistem pengukuran kecepatan mempunyai resolusi 0,75 x 10 -1 s, tetapi resolusi secara integral dari alat hanya mampu sekitar 10 -1 s. Nilai viskositas secara teori telah dihitung dan disimulasi untuk mendapatkan nilai viskositas absolut. Hasil simulasi telah dianalisi dan dibandingkan dengan hasil uji percobaan. Faktor koreksi untuk perhitungan kecepatan telah dianalisis dan memberikan nilai optimal faktor koreksi kecepatan sebesar 0,4425, yang mana nilai ini sangat dipengaruhi oleh dimensi tabung dan bola jatuh yang digunakan. Viskositas gliserin yang diperoleh pada percobaan sebesar 1418,0309±1,6157 mPa.s., nilai ini sesuai dengan nilai yang ada di literatur lainnya dan memberikan nilai kesalahan ketepatan (ε 0 ) sebesar 0,57%.Kata kunci: viskositas, metode bola jatuh, perekaman akuisisi data secara langsung

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“…1 The viscosity reflects the resistance of a fluid to flow under an applied shear stress and many different types of viscometers have been developed to achieve this measurement. They may be classified in four main families: capillary viscometers, [2][3][4] rotational or sliding viscometers, 5, 6 falling spheres 7,8 or slender objects, 9 and vibrational viscometers. 10 In the present study, a viscometer based on the measurement of the friction force exerted by a flowing fluid is presented.…”

Section: Introductionmentioning

confidence: 99%

Viscometer using drag force measurements

Noël

Semin

Hulin

et al. 2011

Review of Scientific Instruments

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A robust and precise viscometer using the forces exerted by a laminar flow inside a small duct is presented: the force is measured on a long cylindrical sensor dipped into the flow. Two devices of respective volumes 1.4 and 0.031 ml have been realized, demonstrating that the technique is usable with small fluid volumes. Several Newtonian and non-Newtonian fluids have been tested at shear rates ranging from 0.3 to 10 s(-1) for the first device and from 85 to 2550 s(-1) for the second one. For Newtonian fluids, of viscosities ranging from 10(-3) to 0.1 Pa s, the linear response of the device has been verified and a 90% agreement with the values provided by commercial rheometers is obtained. For non-Newtonian polymer solutions, the variation of the force with the flow velocity allows one to determine the dependence of the viscosity on the shear rate. Two shear thinning polymer solutions with a power law behavior at intermediate shear rates have been investigated and their rheological parameters have been determined.

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Design of a high precision falling-ball viscometer

Cited by 51 publications

References 17 publications

Theory for polymer analysis using nanopore-based single-molecule mass spectrometry

Theory for polymer analysis using nanopore-based single-molecule mass spectrometry

Desain dan Analisis Pengukuran Viskositas dengan Metode Bola Jatuh Berbasis Sensor Optocoupler dan Sistem Akuisisinya pada Komputer

Viscometer using drag force measurements

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