Fabrication of alumina micromixer with two-dimensional serpentine microchannels by centrifuge-assisted micromoulding

A two-dimensional (2D) serpentine mixer was made of alumina using centrifuge-assisted micromoulding. Concentrated aqueous alumina slurry was filled into microstructured polydimethylsiloxane micromoulds with the aid of centrifugation to form green micromixers, which were then sintered to obtain the final products. In contrast to the micromixer fabricated by micromoulding (filling without the aid of centrifugation), it is found that using centrifugation significantly improved the structural integrity of the green micromixer. Straight and serpentine microchannels with rectangular cross-sections were precisely fabricated. After sintering at 1600^oC, defect-free alumina micromixer with a relative density of 98.7%, linear shrinkage of about 18%, hardness of 20.9 GPa, flexural strength of 328.2 MPa and roughness of 143.9 nm was attained. The results show that ceramic microdevices with complex-shaped 2D microchannels (with diameters ≤ 100 μm and aspect ratios ≤ 2) can be reliably fabricated by centrifuge-assisted micromoulding.