Replication of Three-Dimensional Rotary Micromechanism by Membrane-Assisted Transfer Molding

We report a method to replicate not only complex three-dimensional (3D) microstructures with closed loops but also a rotary microstructure restricted to a shaft by using a membrane-assisted transfer molding with a poly(dimethylsiloxane) (PDMS) mold. In this method, the use of supercritical CO 2 drying allows the fabrication of a 3D master structure with partition membranes of submicron thickness by two-photon microfabrication. Because the membranes attached to the master structure separate the PDMS mold under closed loops, the PDMS mold can be released from the master structure that has closed loops or movable microparts. In particular, rotary micromechanisms such as microrotors and micromanipulators were replicated using a cylindrical partition membrane. It was also demonstrated that the replicated movable microparts can be driven in water. The movable microparts will be useful for microfluidic devices and as manipulation tools for biological samples.