Ultrasound-assisted recovery of free-standing high-aspect-ratio micropillars

High-aspect-ratio polymer micropillar arrays are widely employed in microfluidics and microdevices. The collapse of polymer micropillars, however, would induce device degradation, which calls for a recovery method for the collapsed micropillars to restore their performances. In this communication, we propose a cost-effective and robust approach for recovery of free-standing high-aspect-ratio micropillars by ultrasonic-assisted technology. The collapsed micropillar array immersed in a low-surface-energy solution will recover its upright state by ultrasonic stimulation and keep standing steadily due to the low-surface-energy treatment. The collapsed micropillars treated by the proposed approach are entirely able to spring back to their original upright position.