2021/03/06 by Avijit Kundu, Raunak Dey, Kundu, Avijit +5
Engineering · Materials Science · Medicine · #Blood properties and coagulation #FOS: Physical sciences #Material Dynamics and Properties #Microfluidic and Bio-sensing Technologies #Soft Condensed Matter (cond-mat.soft) #Sports Dynamics and Biomechanics
paper · pdf · doi:10.48550/arxiv.2103.04093
openalex publication_date 2021/03/06 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We employ multiple sinusoid modulated optical tweezers to measure the\nfrequency dependent rheological parameters of a linear viscoelastic fluid over\nfive decades of frequency in a single shot, hitherto not achieved using active\nmicrorheology alone. Thus, we spatially modulate a trapped probe particle\nembedded in a fluid medium with a combination of a square wave - which is by\ndefinition a superposition of odd sinusoidal harmonics - and a linear\nsuperposition of multiple sinusoids at a wideband frequency range, with\ncomplete control over the amplitude, frequency and relative phase of the\nmodulating signals. For the latter, we selectively excite the particle by\nlarger amplitudes at high frequencies where the particle response is low,\nthereby enabling wideband active microrheology with large signal-to-noise. This\nmitigates the principal issue associated with conventional active microrheology\n- which is low bandwidth - and also renders our method better in terms of\nsignal to noise, and faster compared to passive microrheology. We determine the\ncomplex viscoelastic parameters of the fluid by extracting the phase response\n(relative to input excitation) of the probe from the experimentally recorded\ntime series data of the probe displacement, and employing well-known\ntheoretical correlations thereafter. We test the efficacy of our method by\nstudying a linear viscoelastic media (polyacrylamide-water solution) at\ndifferent concentrations, and find good agreement of the measured fluid\nparameters with known literature values.\n