Movement of magnetorheological fluid using the rotation of chainlike magnetic-particles driven by rotation magnetic field

This study is an extension of MR fluid (MR fluid: liquid glycerol polymer with magnetic-particles) applications on MEMS devices [1-2], presenting a novel moving technology for MR fluid using the rotation of chainlike magnetic particles (Fig.1). When driven by in-plane dynamic magnetic field, the chainlike magnetic particles inside MR fluid are rotated out-of-plane and further encourage the motion of MR fluid (Fig.1b). MR fluid movement speed and direction can be modulated by (1) weight fraction and chain length of magnetic powder; (2) strength and angular speed of applied magnetic field (Fig.1b); (3) pattern of spiral channel (Fig.1c-d). MR fluid movements are demonstrated on three PDMS dome shaped substrates [3] with no channel, clockwise spiral and counterclockwise spiral channels (Fig.1b-d). Measurement results are summarized in Table 1. Detail investigations are still required to quantitatively predict and precisely control the movement of the MR fluid.