LAUSR

In this paper, we propose a simple fabrication process for an active membrane utilised in the manufacture of micropumps using a photosensitive composite. The composite is developed from a mixture of a negative photoresist (SU-8) and magnetic particles. We evaluated the magnetisation and attractive force of the composites made of Fe3O4, Ni, or Fe. In our experiment, the composite made of Fe (50 wt%) demonstrated the maximum values for magnetisation and attractive force, which were 300 kA/m and 2.7 mN, respectively. The processability of the composite (Fe: 50 wt%) showed a saturated exposure thickness of approximately 25 µm, which was caused by the low transmittance for ultraviolet light in the exposure process. We fabricated a micropump using a simple process, which included the manufacture of both of an active membrane and a hollow structure in a one-step self-aligned photolithography process using above processability of the composite. The fabricated device demonstrated that the displacement of the membrane increased with the increase in the applied magnetic field from 10 kA/m to 90 kA/m. The maximum displacement was 4.2 µm at 5 Hz in an applied magnetic field of 90 kA/m. The flow rate of the micropump was evaluated by particle tracking method and the result was 36.1 nL/min at 5 Hz in 90 kA/m.