Microrheology is a powerful technique for measuring the local viscoelastic properties of materials on a microscopic scale by tracking the motion of embedded microparticles. This technique can be either passive, where the Brownian motion of probe particles is monitored, or active, where the response of microparticles to externally applied forces is measured.
Aresis optical tweezers are ideal for both passive and active microrheology experiments with versatile applications in soft matter (gels, polymers, colloids, emulsions), biological systems (cells, tissues, cytoplasm, extracellular matrix), and other areas, such as pharmaceuticals and cosmetics, where precise measurement at the microscopic scale are crucial.
Aresis optical tweezers provide exceptional laser stability and precise positioning with sub-nanometre resolution, ultra-fast switching times, and integrated direct video capture. A quadrant photodiode particle tracking system can be added to the setup upon request. The advantage of direct video capture is the capability of tracking multiple probe microparticles simultaneously, enhancing the efficiency of the experiment. A specialised field-flattening algorithm, which compensates AOD nonlinearities and beam clipping, ensures reliable and reproducible measurement across the entire viewing field.
Example: Microrheology of dilute bacterial suspensions and biofilm components
Aresis optical tweezers were used to study mechanical coupling of living bacteria both in biofilms and in dilute bacterial suspensions. By trapping and oscillating individual bacteria, the response of bacterial cluster was observed. The researchers discovered that even in dilute suspensions, individual bacteria are mechanically coupled and show long-range correlated motion. They have shown that the bacteria are connected by a fragile network, composed of extracellular matrix and cell debris, which behaves like a viscoelastic fluid of entangled extracellular polymers.
Selected related references:
Viscoelastic properties of levan-DNA mixtures important in microbial biofilm formation as determined by micro- and macrorheology; B. Stojković et al 2014 Biophys. J. 108 758; DOI: 10.1016/j.bpj.2014.10.072 LINK
An early mechanical coupling of planktonic bacteria in dilute suspensions; Simon Sretenovic et al 2017 Nat Commun. 8 213; DOI: 10.1038/s41467-017-00295-z LINK