Demonstration of a bio-microactuator powered by cultured cardiomyocytes coupled to hydrogel micropillars

While previous works on cell-based devices for integrated chemical systems have focused on exploiting biochemical functions of cells, we demonstrated the direct utilization of on-board cells as microactuators converting chemical energy into mechanical energy. The concept of bio-microactuators was demonstrated by using cardiomyocytes to drive hydrogel microstructures. Arrays of hydrogel micropillars made by the replica molding method and modified for cell attachment comprised a supporting scaffold for cardiomyocytes. Primary neonatal rat cardiomyocytes were then cultured directly onto the micropillars, attaching to micropillars successfully. Micropillars coupled to cells beat regularly and spontaneously without any biochemical triggers. The beat frequency was about 0.1 Hz at 20 °C, and the pillar peak displacement beating most strongly in our observation was 6 μm. The contractile force of the cultured cardiomyocytes was estimated by the displacement of the micropillar. Total natural contractile forces of single or a few cardiomyocytes attached to the pillar were observed to exceed 8 × 10−8 N. The demonstrated capabilities should enable fundamental changes in the concept of actuators and cell-hybridized instrumentation.