Expandable microspheres incorporated in a PDMS matrix: a novel thermal composite actuator for liquid handling in microfluidic applications

In this study a novel actuator concept based on expandable microspheres incorporated in a PDMS matrix is presented. Merging the merits of the two substances gives the resulting composite material novel application possibilities as well as novel performance and processing properties. The expansion behavior of the composite was investigated and a maximum volume change of 270% of its original volume was measured after heating to 80/spl deg/C. Applying a heat treatment to the composite shows its capability of filling out deep voids. The composite shows very good applicability as embedded actuator and may be appropriate for various applications. Furthermore, the applicability of the composite for replica molding has been demonstrated by creating inverse replicated features in the cured composite. We show the investigation of fabrication, expansion and application techniques by means of a novel actuator concept for liquid handling.