Oscillating magnetic field enhanced Janus particle swimming in shear flow

The transport of artificial microswimmers is an active research field due to their unique advantages in biological and medical applications, such as drug delivery, surgery, biosensing, minimally invasive medicine, particle separation and environmental treatment. Dynamic magnetic fields, for instance, rotating and oscillating magnetic fields, are often used as actuation strategies due to their noninvasive and biologically inert qualities. Producing oscillations in a magnetic field requires little sophisticated Helmholtz setups, and the field applies a torque in one direction and cannot actuate the motion of a Janus swimmer on a wall. Therefore, we numerically studied the movement of a Janus microswimmer near a wall by coupling an oscillating magnetic field and shear flow, and we found that this method significantly enhances the transport motion of the swimmer compared to shear flow or an oscillating magnetic field alone. Then, we clarified the mechanism of this transport motion, discussed the influences of the magnetic field and shear rate on the swimming speed and direction, and computed the critical relationship parameter for effect of the magnetic susceptibility of the coating and the oscillating magnetic field strength on the motion of the Janus particle. The knowledge obtained in this study is fundamental for understanding the interactions between shear flows and oscillating magnetic fields that affect the transport motion of a Janus microswimmer and provides a useful method for controlling the movement of a Janus microswimmer in shear flows.