Functional 3-D PDMS microchannels having slanted grooves embedded walls realizing spiral flow

This paper presents the functional three-dimensional microchannels whose top and side walls have slanted micro-grooves. These microchannels could generate short pitch spiral flow for efficient chaotic mixing. We proposed a novel fabrication method of the 3-D SU-8 molds using 2 step inclined backside exposures and additional 2 step topside exposures. Since liquid in the channel flows along the grooves on the walls, optimum design of the pitch and placement of the slanted grooves enables efficient spiral flows in the channel.