Passive optical mapping of structural evolution in complex fluids

Guzmán-Sepúlveda, J. R.; Douglass, Kyle M.; Amin, Samiul; Lewis, Neil E.; Dogariu, Aristide

doi:10.1039/c4ra11627e

Cited by 11 publications

(10 citation statements)

References 52 publications

(100 reference statements)

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“…Specifically, the treatment of the signal measured is as follows. It was explained before that the power spectrum of the intensity fluctuations measured, P ( f ), can be decomposed into a collection of discrete representative contributions, , on the basis of single-scattering dominance. , This allows incorporating directly such spectral decomposition into the calculation of the mean-squared displacement (MSD) of the diffusing particles, . In addition, this, in turn, can be used for the estimation of the viscoelastic properties of the suspending medium (for tracers of known size), , , where is the logarithmic slope of the MSD curve.…”

Section: Discussionmentioning

confidence: 99%

“…, on the basis of single-scattering dominance. 36,37 This allows incorporating directly such spectral decomposition into the calculation of the mean-squared displacement (MSD) of the diffusing particles,…”

Section: ■ Discussionmentioning

confidence: 99%

“…On the basis of single-scattering dominance, the power spectrum of the intensity fluctuations measured can be decomposed into a collection of discrete representative contributions, with a i being the relative amplitude, , and τ i the representative relaxation time of the i th population. , …”

Section: Methodsmentioning

confidence: 99%

“…, and τ i the representative relaxation time of the ith population. 36,37 From here, the Stokes−Einstein formulation can be followed to calculate the diffusion properties of the scattering centers, t h a t i s , e ff e c t i v e d i ff u s i o n c o e ffi c i e n t ,…”

Section: ■ Introductionmentioning

confidence: 99%

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Continuous Optical Measurement of Internal Dynamics in Drying Colloidal Droplets

Guzmán-Sepúlveda

Dogariu

2021

J. Phys. Chem. B

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Accessing the colloidal dynamics non-invasively and continuously during the phase transition of a colloidal system is challenging but critical. Here, we demonstrate the use of spatiotemporal coherence-gated light scattering for studying the internal dynamics of drying colloidal droplets. The continuously acquired signal originates from a picoliter-sized volume located at the droplet−substrate interface. The measurement is non-contact, non-invasive, and label free and permits real-time observations of both optical and mechanical changes in the measurement volume. Additionally, some macroscopic descriptors of the drying process can be constructed from the microscopic measurement, providing ample information of the process. Implemented with an endoscopic-like probe, this system can be easily incorporated into the existing drop profiling instruments, which is potential for the full characterization of dynamic colloidal droplets.

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Section: Discussionmentioning

confidence: 99%

Section: ■ Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Continuous Optical Measurement of Internal Dynamics in Drying Colloidal Droplets

Guzmán-Sepúlveda

Dogariu

2021

J. Phys. Chem. B

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“…[33][34][35] Recently, the LC-DLS has been used to map the structural dynamics of self-assembling polymer systems. 36 In this paper, we will show that LC-DLS can be used for characterizing swelling hydrogels where embedded polystyrene (PS) particles are used as probes for structural dynamics. Our approach allows us to continuously monitor the fast-scale diffusion of probe particles over the slow-scale dynamics of the swelling process.…”

Section: Introductionmentioning

confidence: 99%

In situ characterization of structural dynamics in swelling hydrogels

et al. 2016

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Characterizing the structural morphology and the local viscoelastic properties of soft complex systems raises significant challenges. Here we introduce a dynamic light scattering method capable of in situ, continuous monitoring of structural changes in evolving systems such as swelling gels. We show that the inherently non-stationary dynamics of embedded probes can be followed using partially coherent radiation, which effectively isolates only single scattering contributions even during the dramatic changes in the scattering regime. Using a simple and robust experimental setup, we demonstrate the ability to continuously monitor the structural dynamics of chitosan hydrogels formed by the Ag(+) ion-triggered gelation during their long-term swelling process. We demonstrate that both the local viscoelastic properties of the suspending medium and an effective cage size experienced by diffusing probe particles loaded into the hydrogel can be recovered and used to describe the structural dynamics of hydrogels with different levels of cross-linking. This characterization capability is critical for defining and controlling the hydrogel performance in different biomedical applications.

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