Micromachined Straight-Through Silicon MicroChannel Array for Monodispersed Microspheres

An array of through-holes, referred to as straight-through silicon microchannel (MC) was developed as a novel emulsification device for preparing monodispersed microspheres (MS). Micromachining technology including deep reactive ion etching (RIE) yielded uniformly sized straight-through MC on a silicon substrate. The formation characteristics of MS were investigated using a newly fabricated straight-through MC with 17.3 μm equivalent diameter. Monodispersed oil-in-water (O/W) MS with an average diameter of 32.5 μm were successfully formed by forcing the dispersed phase into the continuous phase through an oblong cross-sectional shape of straight-through MC. Their elongated cross-sectional shape contributes significantly to the spontaneous formation of monodispersed MS without any turbulent mixing. Also, this straight-through MC allowed the stable formation of monodispersed MS in a wide range of the applied pressure of the dispersed phase.