Microswimmers in Polymeric Fluids

The study of microswimmers in viscoelastic fluids is important due to their essential role in many biological systems and various industrial and medical applications. This review article summarizes the behavior of microswimmers in complex viscoelastic fluids. Interestingly, both an increase or decrease in the speed and the power efficiency of microswimmers may be observed depending on the swimming pattern and the rheology of the polymeric fluid. First, it introduces the continuum frameworks for a complex fluid in which the microswimmers are present. This study briefly discusses how the reciprocal motion can propel a swimmer in a viscoelastic fluid contrary to the scallop theorem. This is followed by a section on different types of individual swimmers and their theoretical framework. A finite-sized swimming sheet can show the resonance effect when relaxation time matches the characteristic time of the swimming. Lastly, progress on the topic of squirmers in the complex environment is presented, and it is seen that the interaction of the squirmer with the complex fluid is unpredictable. © 2024 Wiley-VCH GmbH.