Laser Speckle Rheology for evaluating the viscoelastic properties of hydrogel scaffolds.

ABSTRACT: Natural and synthetic hydrogel scaffolds exhibit distinct viscoelastic properties at various length scales and deformation rates. Laser Speckle Rheology (LSR) offers a novel, non-contact optical approach for evaluating the frequency-dependent viscoelastic properties of hydrogels. In LSR, a coherent laser beam illuminates the specimen and a high-speed camera acquires the time-varying speckle images. Cross-correlation analysis of frames returns the speckle intensity autocorrelation function, g₂(t), from which the frequency-dependent viscoelastic modulus, G*(?), is deduced. Here, we establish the capability of LSR for evaluating the viscoelastic properties of hydrogels over a large range of moduli, using conventional mechanical rheometry and atomic force microscopy (AFM)-based indentation as reference-standards. Results demonstrate a strong correlation between |G*(?)| values measured by LSR and mechanical rheometry (r?=?0.95, p?-9), and z-test analysis reports that moduli values measured by the two methods are identical (p?>?0.08) over a large range (47?Pa - 36?kPa). In addition, |G*(?)| values measured by LSR correlate well with indentation moduli, E, reported by AFM (r?=?0.92, p?-7). Further, spatially-resolved moduli measurements in micro-patterned substrates demonstrate that LSR combines the strengths of conventional rheology and micro-indentation in assessing hydrogel viscoelastic properties at multiple frequencies and small length-scales.

SUBMITTER: Hajjarian Z 

PROVIDER: S-EPMC5131361 | biostudies-literature | 2016 Dec

REPOSITORIES: biostudies-literature