Validation of Optimal Fourier Rheometry for rapidly gelling materials and its application in the study of collagen gelation

Curtis, D.; Holder, Alexander; Badiei, Nafiseh; Claypole, James; Walters, Matthew J.; Thomas, B. R.; Barrow, M. S.; Deganello, Davide; Brown, M. Rowan; Williams, P. R.; Hawkins, Karl

doi:10.1016/j.jnnfm.2015.01.003

Cited by 26 publications

(30 citation statements)

References 22 publications

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“…%. Figure 5(a) shows the data obtained in the present study (and corrected using the SIC procedure) with the literature data from both Hawkins et al (2008) and Curtis et al (2015a;2015b). Both studies show excellent agreement with the present data despite the fact that the studies have been using differing techniques.…”

Section: Resultssupporting

confidence: 78%

“…Concentration dependence of δ GP . (a) shows data from the present study (0.3-3 Hz, black circles) using standard instrument correction procedures, .2 Hz, SAOS and Fourier Transform Mechanical Spectroscopy, blue triangles) (Hawkins et al, 2008) and Hz, Optimal Fourier Rheometry and Fourier transform mechanical spectroscopy, red squares) (Curtis et al, 2015a;2015b). Excellent agreement between these CMT rheometer based studies is observed, but a clear discrepancy is also evident at 2.5 wt.…”

Section: Resultssupporting

confidence: 53%

“…Whilst at temperatures above the maximum gelation temperature (∼33.6 • C) (Tosh and Marangoni, 2004), gelatin displays near Newtonian rheological properties, upon cooling, a thermoreversible gelation process occurs to form a physically crosslinked biopolymer network (Boedtker and Doty, 1954;Tosh and Marangoni, 2004;and Wolf and Keller, 1996). The thermoreversible nature of gelatin gelation makes the system an ideal test material for studies involving the validation of novel rheometric approaches (Curtis et al, 2015a;Curtis et al, 2015b;and Hawkins et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

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An enhanced rheometer inertia correction procedure (ERIC) for the study of gelling systems using combined motor-transducer rheometers

et al. 2017

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The rheological characterisation of viscoelastic materials undergoing a sol-gel transition at the Gel Point (GP) has important applications in a wide range of industrial, biological, and clinical environments and can provide information regarding both kinetic and microstructural aspects of gelation. The most rigorous basis for identifying the GP involves exploiting the frequency dependence of the real and imaginary parts of the complex shear modulus of the critical gel (the system at the GP) measured under small amplitude oscillatory shear conditions. This approach to GP identification requires that rheological data be obtained over a range of oscillatory shear frequencies. Such measurements are limited by sample mutation considerations (at low frequencies) and, when experiments are conducted using combined motor-transducer (CMT) rheometers, by instrument inertia considerations (at high frequencies). Together, sample mutation and inertia induced artefacts can lead to significant errors in the determination of the GP. Overcoming such artefacts is important, however, as the extension of the range of frequencies available to the experimentalist promises both more accurate GP determination and the ability to study rapidly gelling samples. Herein, we exploit the frequency independent viscoelastic properties of the critical gel to develop and evaluate an enhanced rheometer inertia correction procedure. The procedure allows acquisition of valid GP data at previously inaccessible frequencies (using CMT rheometers) and is applied in a study of the concentration dependence of bovine gelatin gelation GP parameters. A previously unreported concentration dependence of the stress relaxation exponent (α) for critical gelatin gels has been identified, which approaches a limiting value (α = 0.7) at low gelatin concentrations, this being in agreement with previous studies and theoretical predictions for percolating systems at the GP.

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Section: Resultssupporting

confidence: 78%

Section: Resultssupporting

confidence: 53%

Section: Introductionmentioning

confidence: 99%

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An enhanced rheometer inertia correction procedure (ERIC) for the study of gelling systems using combined motor-transducer rheometers

et al. 2017

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“…Hence, in systems undergoing gelation, identification of a CG state requires the viscoelastic properties of a material to be monitored as a function of both time and frequency. This has been successfully achieved for a range of gelling systems through the sequential application of (i) a series of oscillatory waveforms with discrete frequency (a frequency sweep approach), (ii) a multicomponent waveform (FTMS) [42][43][44], and (iii) a frequency modulated waveform [45,46]. In this work, FTMS was used to monitor the approach to the CG before a step-strain experiment was performed on the material at the CG state.…”

Section: Aqueous Solution Of Gelatinmentioning

confidence: 99%

i-Rheo: Measuring the materials' linear viscoelastic properties “in a step”!

Tassieri

Laurati

Curtis

et al. 2016

Journal of Rheology

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We present a simple new analytical method for educing the materials' linear viscoelastic properties, over the widest range of experimentally accessible frequencies, from a simple step-strain measurement, without the need of preconceived models nor the idealization of real measurements. This is achieved by evaluating the Fourier transforms of raw experimental data describing both the time-dependent stress and strain functions. The novel method has been implemented into an open access executable "i-Rheo," enabling its use to a broad scientific community. The effectiveness of the new rheological tool has been corroborated by direct comparison with conventional linear oscillatory measurements for a series of complex materials as diverse as a monodisperse linear polymer melt, a bimodal blend of linear polymer melts, an industrial styrene-butadiene rubber, an aqueous gelatin solution at the gel point and a highly concentrated suspension of colloidal particles. a)

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“…Poulesquen [47] have used chirp signals to measure the viscoelastic spectra of different materials, claiming this method to be an Optimal Fourier Rheometry (OFR) technique [45,46]. However, a rigorous investigation of high resolution data on a model polymer network reveals that the measurement precision can be severely compromised especially when using short duration chirp signals.…”

Section: Introductionmentioning

confidence: 99%

Time-Resolved Mechanical Spectroscopy of Soft Materials via Optimally Windowed Chirps

et al. 2018

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The ability to measure the bulk dynamic behavior of soft materials with combined time-and frequency-resolution is instrumental for improving our fundamental understanding of connections between the microstructural dynamics and the macroscopic mechanical response. Current state-ofthe-art techniques are often limited by a compromise between resolution in the time and frequency domain, mainly due to the use of elementary input signals that have not been designed for fast time-evolving systems such as materials undergoing gelation, curing or self-healing. In this work, we develop an optimized and robust excitation signal for time-resolved mechanical spectroscopy through the introduction of joint frequency-and amplitude-modulated exponential chirps. Inspired by the biosonar signals of bats and dolphins, we optimize the signal profile to maximize the signal-to-noise ratio while minimizing spectral leakage with a carefully-designed modulation of the envelope of the chirp, obtained using a cosine tapered window function. A combined experimental and numerical investigation reveals that there exists an optimal range of window profiles (around 10% of the total signal length) that minimizes the error with respect to standard single frequency sweep techniques. The minimum error is set by the noise floor of the instrument, suggesting that the accuracy of an optimally windowed chirp (OWCh) sequence is directly comparable to that achievable with a standard frequency sweep, while the acquisition time can be reduced by up to two orders of magnitude, for comparable spectral content. Finally, we demonstrate the ability of this optimized signal to provide time-and frequency-resolved rheometric data by studying the fast gelation process of an acid-induced protein gel using repeated OWCh pulse sequences. The use of optimally windowed chirps enables a robust time-resolved rheological characterization of a wide range of soft materials undergoing rapid mutation and has the potential to become an invaluable tool for researchers across different disciplines.

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Validation of Optimal Fourier Rheometry for rapidly gelling materials and its application in the study of collagen gelation

Cited by 26 publications

References 22 publications

An enhanced rheometer inertia correction procedure (ERIC) for the study of gelling systems using combined motor-transducer rheometers

An enhanced rheometer inertia correction procedure (ERIC) for the study of gelling systems using combined motor-transducer rheometers

i-Rheo: Measuring the materials' linear viscoelastic properties “in a step”!

Time-Resolved Mechanical Spectroscopy of Soft Materials via Optimally Windowed Chirps

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